Carrier Concentration Profiles Research Articles

Performance analysis of dual material control gate cavity on source electrically doped TFET biosensor for biomedical applications

The fabrication complexity, low sensitivity, detection speed, and costs associated with nanoscale devices have been significant concerns in the development of label-free biosensors. To address these issues, we report a novel dual material control gate cavity on source electrically doped tunnel field-effect transistor (DM-CG-CS-ED-TFET) for label-free biosensors. In this regard, the n+ drain and p+ source regions within the proposed device are induced by applying polarity gate (PG) bias voltages of PG-1 = +1.2 V and PG-2 = −1.2 V, respectively, across the respective polarity gate electrodes. This approach not only overcomes doping control issues but also avoids thermal budget constraints and minimizes fabrication complexity when compared to conventional TFET. For biomolecule sensing in the device, a nanogap cavity is created within the gate dielectric by selectively etching a portion of the polarity gate dielectric layer towards the source side. The performance of the proposed biosensor device is evaluated based on the variations in carrier concentration profile, energy band diagram, electric field, transfer (IDS - VGS) characteristics, drain current (IDS) sensitivity, ON-state current (ION) sensitivity, switching ratio (ION/IOFF) and subthreshold swing (SS) sensitivity. The sensitivity of the device is also investigated based on nano-cavity dimensions, practical challenges such as various filling factors, and the step profile generated from the steric hindrance. Moreover, the effect of temperature on sensitivity has also been investigated. For this, various biomolecules including Streptavidin (k = 2.1), APTES (k = 3.57), ferrocytochrome c (k = 4.7), keratin (k = 8) and Gelatin (k = 12), have been investigated for their performance using Silvaco ATLAS device simulator. The simulation results demonstrate that the proposed biosensor is a viable option for biosensing applications in biomedical engineering.

Carrier density distribution in AlGaAs/GaAs superlattices with different numbers of quantum wells determined by capacitance-voltage profiling

The charge carrier density distribution in uniformly doped AlGaAs/GaAs superlattices with layer thicknesses of 1.5/10 nm and different numbers of quantum wells was studied. Both energy band theory and capacitance–voltage profiling were used to determine the carrier concentration profiles of the structures. During the analysis of the experimental and simulated capacitance–voltage characteristics, it was found that the maximum electron concentrations increase with an increase in the number of quantum wells from ∼ 7.1⋅1016cm−3 for three wells to ∼ 9.3⋅1016cm−3 for 25 wells with an overall superlattice doping level of ∼ 1017cm−3.

Novel Low-Loss Reverse-Conducting Insulated-Gate Bipolar Transitor with Collector-Side Injection-Enhanced Structure

In this paper, a new concept of low-loss Reverse-Conducting Insulated-Gate Bipolar Transistor with Collector-side Injection-Enhanced structure (RC-IGBT-CIE) is proposed and investigated using simulations. In reverse conduction (the on state of the diode mode), the CIE structure enhances the collector-side carrier concentration of the proposed RC-IGBT-CIE, which results in low reverse-conducting voltage (VF). The low reverse recovery loss and low turn-on loss using an inductive load circuit are obtained by using the modified carrier concentration profile resulted from both the CIE effect and the low-injection-efficiency p-emitter. Simulation results show that, with the same sum of turn-on loss and reverse recovery loss (Eon + Erec), when compared to conventional RC-IGBT with anti-parallel thyristor (RC-IGBT-thyristor), the RC-IGBT-CIE reduces VF by 9.2%, and meanwhile, with the same total conducting voltage (Von, sat + VF), the total switching loss (Eoff + Eon + Erec) is reduced by 20.9% but does not sacrifice short-circuit capability.

29‐4: Higher External Quantum Efficiency with Lower Current Density Injection of <10 μm Pixel Size Arrays for Display Application

In this paper, the gallium nitride (GaN) based Micro‐LED was fabricated based on a self‐aligned process with hydroxide treatment and ALD passivation from 100 μm down to 3 μm. The different current spreading performance was characterized based on the series resistance analysis. Then the size‐dependent carrier concentration profile was demonstrated via the capacitancevoltage measurement, identifying the various carrier injection behavior by different size. Finally, the external quantum efficiency and luminance versus current density dependence for array device and the single device was compared, revealing a higher efficiency at lower current density for array device, which is favorable for display application.

On the interpretation of confocal spectral depth profiling of color center and carrier concentration by photoluminescence and Raman of implanted 4H–SiC

Point defects in silicon carbide (SiC) formed after ion implantation can serve as color centers for quantum sensing, or as donors or acceptors to provide carriers to influence electrical performance. Confocal spectroscopic characterization allows the determination of point defect-related optical and electrical properties without sample preparation or destruction. However, phenomena such as refraction and aberration can complicate the interpretation of the results of three-dimensional spectroscopy. Here, we used H+, N+ and He+ implantation to fabricate silicon vacancy (VSi) color centers in SiC and used confocal spectroscopy to characterize bulk and thin layer of VSi contained materials. 270 keV H+ is more advantageous than 150 keV N+ in preparing VSi due to the preservation of better lattice integrity. For thin-layer VSi samples, the photoluminescence intensity maxima of VSi were distributed at 2–6.5 μm above the surface. To explain such confusing phenomenon in depth profiles focusing on and above the surface the effective excitation volume and chromatic aberration are discussed and proposed for explanation of the results. Furthermore, the ion-implanted layer exhibits a non-negligible effect on the underlying signal during confocal spectral depth profiling, which is attributed to the refraction-related focus degradation.

3.3: Higher External Quantum Efficiency with Lower Current Density Injection of <10 μm Pixel Size Arrays for Display Application

In this paper, the gallium nitride (GaN) based Micro‐LED was fabricated based on a self‐aligned process with hydroxide treatment and ALD passivation from 100 μm down to 3 μm. The different current spreading performance was characterized based on the series resistance analysis. Then the size‐dependent carrier concentration profile was demonstrated via the capacitancevoltage measurement, identifying the various carrier injection behavior by different size. Finally, the external quantum efficiency and luminance versus current density dependence for array device and the single device was compared, revealing a higher efficiency at lower current density for array device, which is favorable for display application.

Исследование отражения плоской электромагнитной волны от неоднородного плазменного слоя, расположенного на идеально проводящей плоскости

A method for numerical modelling of the reflection of an electromagnetic wave from a planar plasma layer with an inhomogeneous electron density of particles covered of an ideally conducting plane is proposed in the work. The frequency responses of wave reflection coefficients modules are calculated for various incidence angles and electron density profiles of carriers using the differential sweep method. The paper shows that in the region of plasma resonance the plasma layer with a parabolic profile of charge carrier concentration has the lowest reflection level. The effect of the effective frequency of electron collisions in an inhomogeneous plasma layer on the reflection level was studied in this work.

A numerical study on the relationship between the doping and performance in P3HT:PCBM organic bulk heterojunction solar cells

In this study, we perform a simulation analysis to investigate the influence of p-type and n-type doping concentration in BHJ SCs using the drift-diffusion model. Specifically, we investigate the effect of doping on the charge carrier transport and calculate the above-mentioned device parameters. We show that doping the active layer can increase the cell characteristic parameters, that the results are in an excellent agreement with the experimental results previously reported in the literature. We also show that doping causes space charge effects which subsequently lead to redistribution of the internal electric field in the device. Our results reveal that higher doping levels lead to screening the electrical field in the P3HT:PCBM active region. This in turn forces the charge carrier transport to be solely dominated by the diffusion, consequently decreasing the performance of the device. We also show that doping of the active layer to an optimum level can effectively improve the charge transport. Moreover, we show that doping can create an Ohmic contact between the organic and cathode interface. Additionally, the charge carrier concentration profile shows that by increasing the dopant concentration, the J_{sc} can be improved remarkably. Upon doping the active layer, this indicates that illumination can simply reduce the series resistance in the device.

Quantitative measurement of the charge carrier concentration using dielectric force microscopy

The charge carrier concentration profile is a critical factor that determines semiconducting material properties and device performance. Dielectric force microscopy (DFM) has been previously developed to map charge carrier concentrations with nanometer-scale spatial resolution. However, it is challenging to quantitatively obtain the charge carrier concentration, since the dielectric force is also affected by the mobility. Here, we quantitative measured the charge carrier concentration at the saturation mobility regime via the rectification effect-dependent gating ratio of DFM. By measuring a series of n-type GaAs and GaN thin films with mobility in the saturation regime, we confirmed the decreased DFM-measured gating ratio with increasing electron concentration. Combined with numerical simulation to calibrate the tip–sample geometry-induced systematic error, the quantitative correlation between the DFM-measured gating ratio and the electron concentration has been established, where the extracted electron concentration presents high accuracy in the range of 4 × 1016 – 1 × 1018 cm−3. We expect the quantitative DFM to find broad applications in characterizing the charge carrier transport properties of various semiconducting materials and devices.

Determination of the electron distribution in thin barrier AlGaAs/GaAs superlattices by capacitance-voltage profiling

Electron density distribution in uniformly doped AlGaAs/GaAs superlattices with respective layer thicknesses 1.5/10 nm and a different number of quantum wells was investigated. Experimental samples containing 3, 5 and 25 periods with the same layer parameters were grown by molecular beam epitaxy. Capacitance-voltage profiling was used to determine the carrier concentration profiles in the structures both numerically and experimentally. During the analysis of experimental capacitance-voltage characteristics it was found that the maximum electron concentration increases with an increase in the number of quantum wells starting from 7,1∙1016 сm–3 for 3 wells up to 9,2∙1016 сm–3 for 25 wells with overall superlattice doping level of 1017 сm–3. In some samples saturation areas are observed on the concentration profiles, that are associated with the region of superlattice. Concentration values, obtained from computer modeling, correspond to the experimental data with an error of less than 10 %. Capacitance-voltage profiling is a suitable technique for determining the carrier concentration profiles in thin barrier superlattices. Despite the fact that the method provides distribution of the “apparent” carrier concentration profile, it can be used to estimate the dopant atoms distribution in the strongly coupled quantum well heterostructures.

TiO2 and C60 transport nanolayers in optimized Pb-free CH3NH3SnI3-based perovskite solar cells

A Pb-free perovskite solar cell has been designed based on methylammonium (MA) tin-iodide (CH3NH3SnI3). The effect of electron transporting layer (ETL) material on the performance of the solar cell has been studied through substituting the ETL by TiO2 and C60 nanolayers. The energy level and charge carrier concentration profiles of the solar cells have been obtained for better understanding the involved mechanisms. The TiO2-containing solar cell showed the maximum power conversion efficiency (η) of ∼25.5 % at room temperature, with open circuit voltage, short circuit current density and filling factor of ∼1.06 V, 33.0 mA/cm2 and 73.1 %, respectively. Although the C60-containing perovskite solar cell presented a lower η with the value of ∼20.8 %, it could present a higher external quantum efficiency at NIR wavelength region, as compared to the TiO2-containing cell. These results can excite further investigation about the role of ETL nanomaterials in the performance of Pb-free perovskite solar cells.

Inverse Design of Silicon Photonic Modulators

A novel shape optimization procedure is formulated for obtaining a higher phase change while maintaining high transmission in phase modulators. The formulation is implemented as a shape optimization tool. Subwavelength grating-based Si carrier depletion and carrier injection modulators are considered for testing the optimizer. Carrier transport simulations were performed to extract the carrier concentration profiles and were used in the optimizer. The optimized structures are then validated using simulation for transmission and phase change. The results show that the optimization tool developed can optimize both carrier injection and depletion type modulators, in terms of both transmission and phase modulation. The optimized structures can be placed in a ring or Mach-Zehnder modulator to make compact modulators with low drive voltages.

Charge carrier transport and electrical response by driving band gap modulation in semiconductors

Electrical responses and carrier transport dynamics in intrinsic bulk semiconductors are found when a variable gradient in a physical property or field causes a gradient in the band gap and, in turn, in the carrier concentrations. A variable carrier concentration profile leads to a dynamic carrier diffusion flow. The electrical responses depend on temperature and the difference between electron and hole mobilities. This novel effect is evaluated for both open-circuit and closed-circuit configurations. One example is a variable carrier concentration created by acoustically stimulated band gap modulation. A standing acoustic wave in the lattice produces a dynamic pressure-induced variable band gap modulation. Responses from an indium antimonide crystal in acoustic resonance with amplitude of 2.23 MPa (rms) are found to be in the ranges of 30–40 mA and 0.1–0.3 mV for closed and open circuit cases, respectively. At room temperature, quantum effects do not contribute significantly to the description of carrier behavior and transport, except for scattering. The effect can also be produced by perturbations other than pressure if the band gap depends on those perturbations. The electrical responses characteristic of these semiconductors can be used for developing new sensors or transducers to measure gradients, such as pressure gradient transducers.

Dopant Activation Depth Profiling for Highly Doped Si:P By Scanning Spreading Resistance Microscopy (SSRM) and Differential Hall Effect Metrology (DHEM)

Heavily n-doped epitaxially grown Si layers are of great importance for source/drain (S/D) application in advanced node nMOS devices. For contact resistivity reduction, the dopant activation level is very important. Various techniques are being used to evaluate dopant activation in Si:P layers. Among these two methods are Scanning Spreading Resistance Microscopy (SSRM) and Differential Hall Effect Metrology (DHEM). SSRM uses an atomic force microscope equipped with a hard conductive probe that is scanned in contact mode on the cross-sectioned sample’s surface and measures spreading resistance. Measured resistance values as a function of depth are converted into resistivity and carrier concentration depth profiles using calibration measurements and conversion relationships. DHEM provides depth profiles of mobility, resistivity and carrier concentration through a semiconductor layer by making successive sheet resistance (Rs) and Hall voltage measurements using Hall effect/Van der Pauw techniques, as the electrically active thickness of the layer is reduced through successive oxidation steps. Controlled oxidation is achieved by electrochemical anodization. Data collected can then be processed to yield the depth profiles. In this contribution we have carried out SSRM and DHEM measurements on Si:P epi layers subjected to different processing conditions including annealing and ohmic contact fabrication. Secondary Ion Mass Spectrometry (SIMS) was used to measure the total (active + inactive) dopant profiles through the films. Effects of these processes on dopant diffusion and activation were studied and the results from DHEM and SSRM were compared.In-situ phosphorus (P) doped Si epi-layers were grown over 300mm diameter boron doped monitor wafers. While one set was kept as the reference, a second set was treated by a spike-annealing process at 1000 °C. In a third set a Ti/TiN contact fabrication process was carried out and the contact was removed before analysis. In the fourth set contact process was applied to the spike annealed wafer before removal of the Ti/TiN layers. Bulk sheet resistance measurements were made using 4-point probe (4PP) for all the samples. SSRM measurements were carried out at IMEC. Cross-shaped Van der Pauw test-patterns were formed on 8mmx8mm areas on the samples and DHEM measurements were performed at ALP. Figure below shows the dopant depth profiles obtained by SIMS and the carrier concentration profiles from DHEM and SSRM techniques for samples D02 (as deposited Si:P) and D03 (spike annealed). One can make some general observations from the data in this figure. The total dopant concentration as measured by SIMS is ~ 1.4E21/cm3. There is only a small difference in the total dopant distribution profiles (SIMS) between the as deposited sample and the spike annealed sample. However, the spike annealed sample shows much higher dopant activation as measured by DHEM. Carrier concentration is ~2.5x higher in sample D03 (~5E20/cm3) compared to sample D02 (~2E20/cm3). Activation levels measured by SSRM, however, are lower for both samples, and the peak carrier concentration value increases only slightly upon spike annealing, going from ~2E20/cm3 in sample D02 to ~2.2E20/cm3 in sample D03. DHEM clearly indicates the sharp interface between the p-type substrate and the n-type epi-layer and its depth calibration agrees well with the expected thicknesses of the epi layers. The tail of the SSRM data is much more graded. Data from other samples will be presented and discussed in the final manuscript. Figure 1

Role of front and back contacts in the performance of TiO2/CuO heterojunction solar cells

In this work, the effects of front and back contact work functions on the performance of a TiO2/CuO heterojunction solar cell were studied using numerical simulations. Our findings revealed a high device efficiency of ∼ 18 %, and VOC ∼ 0.83 V can be obtained when the work function values of the front transparent conducting oxide (TCO) electrode are below 4.6 eV, provided the metal at the back contact has a work function above 5.1 eV. The underlying cause of this observation can be explained by the carrier concentration profiles across the device, which indicate the formation of a higher potential barrier for the majority carriers at front contact/emitter interface, for front contact work functions (ϕFC) above 4.6 eV, due to which relatively lesser electrons are collected at the electrode. Compared to this, a lower potential barrier for the majority carriers develops when ϕFC < 4.6 eV, implying higher electron collection at the front electrode. At the absorber/back contact interface, formation of a higher potential barrier for the holes impedes their collection when the metal back contact with work function values below 5.1 eV.

Distribution of charge carrier concentrations in epitaxial Ge and GeSn layers grown on n-=SUP=-+-=/SUP=--Si(001) substrates

Heteroepitaxial Ge or Ge1-xSnx layers were grown by hot-wire chemical vapor deposition on Si(001) substrates doped heavily with a donor (As or Sb) impurity. The same layers were also grown on high-resistance Si(001) substrates for comparison. The depth profiles of carrier concentration were measured in both types of layers using the capacitance-voltage method, and carrier mobilities were measured additionally by the Hall effect method in layers on high-resistance silicon. It was found that the layers grown on high-resistance substrates were p-type, while the layers grown in the same regimes on heavily doped substrates were n-type with electron concentration n=(4-9)·1016 cm-3 in Ge layers and n=(2-4)·1017 cm-3 in GeSn layers. It was established experimentally and theoretically that the effect of autodoping of Ge and GeSn layers is lacking in the hot-wire chemical vapor deposition method. In our view, the growth of n-type Ge and GeSn layers on n+-Si(001) substrates doped heavily with a donor (As or Sb) impurity is associated with the segregation of this impurity in the process of growth of a buffer Si layer and its subsequent incorporation into growing Ge or GeSn layers. Keywords: epitaxy, doping, Ge, Si, Sn, concentration.

Low-loss Ge waveguide at the 2-µm band on an n-type Ge-on-insulator wafer

Integrated mid-infrared (MIR) photonics has been widely investigated for the past decade, where germanium (Ge) is a promising optical material in this regime. In this work, we studied the origin of optical losses in Ge waveguides on a Ge-on-insulator (GeOI) wafer fabricated using Smart-cut. We observed that the high optical loss was mainly due to the holes in Ge films, which were generated by crystal defects formed by hydrogen ion implantation for Smart-cut. Furthermore, we found that the carrier concentration profile after the splitting process in remaining Ge films depends on the hydrogen ion implantation energy and initial background doping concentration of Ge wafers. A higher proton implantation energy can lead to deeper penetration of hydrogen ions into Ge films with less damage remaining near the implantation surface, resulting in the successful fabrication of an n-type GeOI wafer with a low carrier density. As a result, we experimentally demonstrated a low-loss Ge waveguide on an n-type GeOI wafer with a propagation loss as low as 2.3 ± 0.2 dB/cm. This work suggests an approach to tailor the carrier type in a Ge film formed using Smart-cut for large-scale MIR Ge photonic integrated circuits.

Influence of the properties of p-a-Si:H layer and the work function of front contact on silicon heterojunction solar cell performance

Heterojunction c-Si and hydrogenated amorphous silicon (a-Si:H) devices with intrinsic a-Si:H thin layer, known as HIT solar cells, are promising alternatives to conventional c-Si solar cells for the possibility of higher open circuit voltage, low temperature processing and lower costs. We have studied the influence of the properties of p-a-Si:H layer and the work function of the front electrode material on the performance parameters of n-c-Si based HIT solar cells using numerical simulation. The findings are further analyzed using energy band diagrams and carrier concentration profiles at the heterointerface of a-Si:H/n-c-Si to reveal the underlying charge transport mechanisms.

(Invited) Characterization of Doping and Activation Processes Using Differential Hall Effect Metrology (DHEM)

As advanced CMOS technology scaling goes beyond 7nm node, contact resistivity becomes an important factor influencing device performance. Approaches to reduce contact resistivity involve advanced doping techniques that yield very high degree of dopant activation at the semiconductor layers comprising the source and drain regions. These approaches include in-situ heavily doped epi layers and ion implantation followed by advanced annealing techniques. Irrespective of the approach used in wafer processing, accurate analysis of dopant activation within the top few nanometers of the surface is critical to understanding the effectiveness of such processes on improving contact resistivity. Similarly, correlation of mobility depth profile to defectivity in the layers helps one to understand how process variables may affect the ultimate electrical properties.Differential Hall Effect Metrology (DHEM) is the only method that can provide mobility and active dopant depth profiles through semiconductor layers at sub-nm resolution. The method employs electrochemical means of reducing the electrically active thickness of a semiconductor film and determining the sheet resistance and mobility of the thinned down layer using Van der Pauw/Hall effect type measurements [1].In this work we characterized an ion implantation/annealing process cycle using DHEM and TEM studies. The sample was a p-type Si wafer ion implanted with P (10keV, 2E15cm-2). After implantation, the wafer was coated with positive photoresist, exposed, and developed in order to define a cross-shaped Van der Pauw structure. After formation of the DHEM test patterns using dry etching, wafer pieces were processed by rapid thermal anneal (RTA) at 750 ºC, 850 ºC, and 950ºC in nitrogen ambient for 30 seconds. After annealing, samples were subjected to a negative photoresist process in order to open contact windows. After the exposure and development, native oxide was removed from the contact windows and metallic contacts were evaporated. Depth profiles of resistivity, mobility, and carrier concentration were measured by DHEM using an ALPro™ 50 electrical profiling tool.Fig. 1 shows the cross-sectional TEM images of the P ion implanted samples after annealing at (a) 750ºC, (b) 850ºC, and (c) 950ºC. As can be seen in Fig 1(a) the end of range (EOR) defects are located at approximately 26-30 nm from the surface in this sample. The 750ºC RTA process did not adequately resolve these defects. However, it is clear from the TEMs that defects at the original location of the a-Si/c-Si interface decreased gradually when the samples were annealed at increasing RTA temperatures (see Fig. 1(b−c)), when crystallinity of the ion implanted top layer also improved.The depth profiles of active carrier concentration after RTA process are given in Fig.2(a). Three regions can be discussed in these depth profiles. Region 1 is within 15nm of the surface, region 2 is at around 20-30 nm depth, and region 3 is at depths at or larger than 40nm. As can be seen in this figure, higher and higher RTA temperatures result in diffusion of P impurities deeper, and dopant activation at region 3 gets higher and higher as the anneal temperature is increased from 750ºC to 950ºC. As for the region 1, we observe a small decrease in carrier concentration values with higher temperature (from about 3.77E+20 #/cm3 to about 2.95E+20 #/cm3) as the overall active dopant profile becomes more uniform due to diffusion.Figure 2(b) shows the mobility depth profiles of the three samples discussed with reference to Fig. 1 and Fig. 2(a). It is obvious from this figure that the mobility profile is relatively flat within the implantation region (<30nm). Notably the mobility value for the RTA 750ºC sample dips at a depth in the range of 25-30 nm, where Fig. 1(a) shows extensive EOR defectivity. Therefore, the correlation with deteriorated mobility at that region is excellent. It is also clear from the mobility data that as the annealing temperature is raised to 850ºC and then to 950ºC this dip in mobility disappears, suggesting reduction in defects through higher temperature annealing. Deeper region (>40nm) mobility reduces with increasing temperatures because of increased carrier scattering mechanisms as more of the dopant is activated deeper at the elevated temperatures.Through this work we have demonstrated how DHEM technique can be utilized to correlate electrical and physical data obtained from samples subjected to doping processes. At the present time we are extending this work to ultra shallow junction structures and these results will be presented at the conference.

Sub-nm Near-Surface Activation Profiling for Highly Doped Si and Ge Using Differential Hall Effect Metrology (DHEM)

Contact resistivity at the metal-semiconductor interface is a strong function of the carrier concentration in the near surface. For next generation 2D/3D MOSFET transistors, industry has been investigating very highly doped materials (>1x1021cm-3) approaching alloy concentrations in Silicon and various Silicon-Germanium materials. All the while, contact development in Ge NMOS has favored co-doping approaches. Regardless of the material system, it is very important to accurately measure near-surface dopant activation. In this paper, we use Differential Hall Effect Metrology (DHEM) implemented on the ALPro™ tool to characterize the activation profiles in both materials. The method employs electrochemical means of reducing the electrically active thickness of a semiconductor film and determining the sheet resistance and mobility of the thinned down layer using Van der Pauw/Hall effect type measurements. By repeating this process and using differential equations, depth profiles of mobility and carrier concentration are obtained [1] at sub-nm resolutions.It is difficult to achieve high n-type dopant activation in Ge. Point defects in Ge are known to behave as acceptor sites and reduce the overall free electron density, particularly near the surface. Minimization of these defects is essential to achieving high performance Ge NMOS. Accurate analysis of dopant activation within 5 nm of the surface is critical to understanding effectiveness of various process steps on improving contact resistance. We have previously published a study on the effect of Ge co-doping with Sb and P on near-surface dopant activation. In Ge with only P-doping it was found that only ~5x1018cm-3 or 5% of the total surface dopants (~1x1020cm-3) were electrically active. With Sb as a co-dopant, the active electron concentration increased to ~2x1019cm-3 with a similar P chemical concentration. Prior work has shown similar increases in activation with co-doping but did not capture the significant decrease in electron concentration by 4x within 10 nm of the surface. Here, we further study the effects of the implantation and annealing processes on near-surface dopant activation in n-type Ge. Samples were prepared by growing 3 µm thick epi-Ge layers on Si substrates. Sample 1 was capped with 20 nm SiO2 and Sample 2 was capped with 20 nm Al2O3 to minimize implant damage and control implant depth. Both samples were implanted first with Sb (dose: 6x1014cm-2, energy: 65 keV) followed by P (dose: 6x1014cm-2, energy: 90 keV). Post-implant anneal was done at 500°C for 10 s in N2 to activate the dopants. ALProTM and SIMS measurements were done to characterize active dopant concentration and total chemical dopant concentration, respectively. The Al2O3 capped sample (Sample 2) showed significantly lower carrier concentration than the SiO2 capped sample (Sample 1) throughout the depth of the profile (Figure 1). Carrier concentration at the surface was lower by nearly an order of magnitude, decreasing from ~2x1019cm-3 to ~2x1018cm-3. Additionally, the peak concentration decreased from 1x1020cm-3 to 5x1019cm-3 at a depth of ~30 nm in both cases. The variations in the carrier profile for the Al2O3 capped sample also indicate greater process variation. SIMS profiles show that there is significant diffusion of Al into the Ge matrix after implant and anneal. Al chemical concentration is 1x1020cm-3 at the Ge surface and steadily decays up to a depth of more than 300 nm. This indicates that there is significant damage caused during the implantation process and the activation anneal is not enough to remove these defects. Al atoms then diffuse from the Al2O3 capping layer into the highly defective Ge substrate. Al is a p-type dopant in Ge and counter-dopes the Sb and P implants to reduce overall electron concentration in Sample 2. It is important to note the high resolution DHEM technique was able to resolve this important phenomenon right near the surface of the material.Additionally, we present early data on very highly phosphorus-doped (~1x1021cm-3) epitaxial silicon thin films grown on Si substrates. In very highly doped Silicon materials, the effect of near-alloy levels of dopant in the matrix on dopant deactivation is not well-known. Samples were obtained with different levels of dopant concentration above ~1x1021cm-3and different anneal temperatures. It was found that near-surface activation in these un-capped samples led to a lowering of activation in the <20nm region from the surface. Extensive post-DHEM metrology (using TEM and SIMS analysis) will also be presented demonstrating control and precision of DHEM data.