Silicon Interface Research Articles

Characterization of Electric Field Induced Ion Migration in Semiconductor Encapsulation Materials

: In modern high voltage power semiconductor technologies ion migration is a highly relevant challenge owing to ongoing miniaturization and operation at higher temperatures. Strong electric fields may cause an enrichment of mobile ions in the gate- and field oxide of the transistor which in turn may result in a shift of the threshold or breakdown voltage leading to chip failure. Therefore it is of strong interest to investigate ion migration in modern semiconductor devices. One of the main contamination sources for mobile ions in semiconductor devices is the molding compound used for encapsulation. These materials consist of various substances such as the polymeric matrix, filler materials for mechanical strength, adhesion promoters and flame retardants. In the elaborated production process of these compounds, mobile ion contamination cannot be avoided. Their small ionic radii and their high abundance make sodium, potassium and chlorine the most critical contaminations responsible for mobile ion induced chip failure. The quantitative analysis of concentration and distribution of these impurity ions in modern semiconductor devices is thus urgently needed. A promising analytical technique for measuring the concentration of these ion contaminations is inductive coupled plasma mass spectroscopy (ICP-MS). Experiments show that different ion concentrations were measured with different digestion methods. For instance the sodium content of a commercially available mold compound, measured with a microwave digestion was more than 6 times higher than the same compound measured with a pressure digestion and water extraction. These differences indicate that there are different ion contamination sources within the mold compound with different chemical properties. It seems to be obvious that different chemical properties lead to different field induced ion migration. Therefore it is of great interest to develop an analytical tool allowing the unambiguous measurement of ion migration properties of different mold compounds. Previous publications [1], [2] show techniques to measure ion diffusion in microcircuit encapsulation materials. However, these measurements do not cover electric field induced ion migration. In the present work a measurement setup based on thin film samples with simplified well-defined geometry was used to measure ion migration in encapsulation materials [3]. To that purpose thin samples of standard processed mold compounds were assembled between two silicon wafer electrodes with well-defined silicon dioxide layers between the mold compound and the electrodes. The sample was heated and a bias was applied between the silicon electrodes. Mobile ions moving from the mold compound to the silicon dioxide / silicon interface were monitored by current measurements. The measurement setup is shown in figure 1. After the measurement the mold compound was removed. Time of flight secondary ion mass spectroscopy (TOF-SIMS) depth profiles of the remaining silicon dioxide layers were recorded, which showed that mobile ions such as lithium, sodium potassium and chlorine moved to the silicon dioxide / silicon interface. Due to the fact that only mobile ions were able to penetrate the silicon dioxide layer, identification and quantification of the migrated ions was possible without the influence of the non-migrated ions, which remain in the mold compound. These measurements can be an important tool to compare different mold compounds and evaluate the risk of mobile ion migration. Acknowledgements: This work was jointly funded by the Austrian Research Promotion Agency (FFG, Project No. 846579) and the Carinthian Economic Promotion Fund (KWF, contract KWF-1521/26876/38867).

Response Simulation and Extraction of Gas Concentrations for Nanostructure Decorated Nano-/Microporous Silicon Interfaces

Sensor and microreactor technology plays a major role in the detection, monitoring, and transformation of materials at interfaces. We study the dynamics of a matrix of reversible interactions of gas analytes with the majority charge carriers of nanostructure modified extrinsic semiconductor interfaces. Nanostructures are deposited on highly sensitive surface layers, created by forming an array of nanopore-coated micropores on p- or n- type silicon semiconductors. The balance of physisorption and chemisorption of the interacting gas analyte on the porous silicon interface is achieved by following the tenants of the developing inverse hard and soft acid/base (IHSAB) interaction model to select metal oxide nanostructures for deposition. These electronically independent metal oxide catalyst sites are readily modified through in-situ nitridation and sulfidation to create a broad sensing matrix. The resulting relative sensor responses of the modified interfaces to gas analytes are explained by the IHSAB interaction model, rather than simply by a shift in system basicity. This expanded matrix of observed sensitivities can then be used to predict the relative response of the interface to a variety of gas phase analytes, as well as direct the choice of porous silicon interface modification for enhanced reversible chemical sensing and electron transduction, in the absence of significant chemical bond formation. The characterization of multiple gas detection, under the guiding model of the IHSAB concept, describes the synergism of two or more analytes simultaneously interacting with an extrinsic semiconductor interface. We are now extending the application of the porous silicon sensors to the identification of organic solvents by measuring impedance. Through the use of an equivalent circuit model, we can explore the physical changes of the porous silicon sensor after metal oxide nanostructure depositions and exposure to various organic solvents.

Increase in Oxide Trap Density Due to the Implementation of High-k and Al2O3 Cap Layers in Thick-Oxide Input-Output Transistors for DRAM Applications

Work function engineering by the introduction of cap layers in a high-k gate stack [1],[2] can be successfully implemented in logic and DRAM peripheral MOSFETs. In the latter case, a so-called Diffusion and Gate Replacement (D&GR) integration scheme has recently been proposed [3], whereby an Al2O3 cap is implemented for tuning the threshold voltage of the p-channel transistors. A key step is the diffusion anneal to form a dipole layer at the SiO2/HfO2 interface [1],[2], which is typically carried out in the range of 600 oC to 900 oC [3]. In addition to the peripheral transistors, also input/output (I/O) devices with a larger gate oxide thickness need to be fabricated in a DRAM chip as well. These may undergo also the HfO2 and Al2O3 deposition and subsequent thermal budget. The question addressed in this work is whether the large Equivalent Oxide Thickness (EOT) devices suffer from these additional processing steps, from a viewpoint of gate oxide quality and reliability. To that aim, low-frequency (LF) noise is used as a tool to probe the border trap profile in the thick oxide gate stack [4],[5]. Evidence will be given for the in-diffusion of Hf and Al in the thick SiO2 up to the silicon interface, giving rise to a strong increase of the oxide trap density and hence the 1/f noise Power Spectral Density (PSD). P-channel transistors have been processed on 300 mm wafers following the conditions of Table 1, with 5 nm SiO2 + polysilicon gate as a reference. The Al2O3 cap is deposited on top of the gate stack. LF noise measurements have been performed on 1 mm×0.170 mm area devices in linear operation (drain-to-source voltage VDS=-0.05 V) with the gate voltage VGS stepped from weak to strong inversion. As shown in Fig. 1, the spectra are typically 1/f-like, with occasionally excess Lorentzian noise components. It is also clear, however, that the frequency exponent is not constant in the studied frequency range from 3 Hz to 100 kHz. It will be shown that the 1/f noise is due to number fluctuations, i.e., is caused by trapping in the gate oxide. From Fig. 2, one can derive that the average input-referred voltage noise PSD (<SVG>) at 10 Hz (Fig. 2a) or 10 kHz (Fig. 2b) strongly depends on the process conditions, with the reference wafer showing at least one decade lower values. Using the formulas in Fig. 3, on can convert the 1/f spectra into an oxide trap density profile, showing a strong increase as soon as a high-k layer is present. The increase in trap density points to an in-diffusion of Hf and Al down to the Si/SiO2 interface, while the reference trap densities are typical for SiO2. It will, finally, be shown that there exists a good agreement between the trend in the oxide trap density derived from 1/f noise spectra and the Negative Bias Temperature Instability (NBTI) of similar p-channel devices. It is clear that for optimizing the quality and reliability of I/O transistors, one should suppress this in-diffusion.

High efficiency organic/silicon hybrid solar cells with doping-free selective emitter structure induced by a WO3 thin interlayer

Organic/silicon hybrid solar cell has recently received intensive interest due to its simple and low-cost fabrication process, which could be potentially used in photovoltaics. However, the efficiency of organic/silicon solar cell needs further improvement. Here, we have introduced a WO3 thin layer between the Ag front electrodes and poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate)(PEDOT:PSS) film in the PEDOT:PSS/silicon solar cell to form a doping-free selective emitter (SE) structure. The carrier recombination is suppressed at the interface of silicon and electrodes, and meanwhile, the contact resistance between the Ag electrodes and PEDOT:PSS film is largely reduced. Therefore, the open-circuit voltage and fill factor of solar cell is significantly improved. As a result, the solar cell with a SE structure displays the power conversion efficiency (PCE) of 11.65%, which is much higher than the one without a WO3 thin layer. These results pave a new way for the fabrication of high efficiency organic/silicon hybrid solar cells.

Ultralow Interface State Density Achieved by Light-Induced Anodization of Aluminum on Silicon Solar Cell Surfaces

A light-induced anodization (LIA) method, which uses the light-induced current of a silicon solar cell to anodize aluminum and form an anodic aluminum oxide (AAO) layer that can reduce recombination at a p-type surface of the cell, is reported. This method can result in anodic oxides with uniform properties over the surfaces of industrially sized silicon wafers since the current flows through the wafer rather than in the surface aluminum layer, as it does when the aluminum is directly electrically contacted. Uniform AAO layers can be formed within 4 min on p-type silicon surfaces by anodizing 300-nm-thick aluminum layers, and when formed over a thin interfacial silicon dioxide layer, the interface state density at the p-type silicon wafer interface can be reduced to values as low as 1 × 10 <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">10</sup> cm <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">-2</sup> ·eV <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">-1</sup> and a fixed charge density of 2 × 10 <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">11</sup> cm <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">-2</sup> . Photoconductance carrier lifetime measurements indicate that these AAO dielectric stack layers are capable of passivating silicon surfaces to a level similar to that provided by silicon nitride layers, which are deposited using plasma-enhanced chemical vapor deposition, although at potentially a much-reduced cost. The high-quality surface passivation, rapid room temperature processing, and large-area uniformity of LIA make it a promising method for producing passivation materials that can further improve efficiency and potentially reduce the cost of photovoltaic solar cells and other p-n junction devices.

Nonequilibrium cross-plane energy transport in aluminum–silicon–aluminum wafer

Transient phonon transport across cross-planes of aluminum–silicon–aluminum combined films is investigated and the Boltzmann transport equation is incorporated to formulate the energy transport in the combined films. Since electrons and phonons thermally separate in the thin aluminum film during heating, the Boltzmann equation is used separately in the electron and lattice subsystems to account for the energy transport in the aluminum film. Electron–phonon coupling is incorporated for the energy exchange between electron and lattice subsystems in the film. Thermal boundary resistance (TBR) is introduced at the interfaces of the silicon–aluminum films. In order to examine the ballistic contribution of phonons on the phonon intensity distribution in the silicon film, frequency-dependent solution of the Boltzmann equation is used in the silicon film and the film thickness is varied to investigate the size effect on the thermal conductivity in the film. It is found that equivalent equilibrium temperature of phonons remains high at silicon–aluminum interface because of the ballistic contribution of the phonons. Equivalent equilibrium temperature for the electron subsystem becomes higher than that corresponding to phonon temperature at the aluminum–silicon interface.

Selective detection of the inorganics NOx, SO2, and H2S in the presence of volatile BTEX contaminants toluene, benzene, and xylene

We demonstrate the highly selective detection of the inorganics NOx (NO, NO2), SO2, and H2S in the presence of toluene, benzene, and xylene using nanostructure metal-oxide-decorated interfaces. This selectivity can be obtained for sensors whose sensitivities are varied for a diversity of nanostructured metal oxides which are applied to a porous silicon (PS) interface. We focus on NOx and SO2 and include additional new evaluations for the response to H2S. In all cases, the response to these inorganic analytes strongly dominates that for toluene, benzene, and xylene. The responses are also consistent with the recently developing inverse hard/soft acid/base concept. The nanostructure metal-oxide-decorated PS conductometric sensors are found to have selectivity ratios well in excess of 104:1 for toluene and benzene and well in excess of 103:1 for xylene. The dominance of the response of these small inorganic sulfur and nitrogen compounds has important implications for the monitoring of significant contaminants associated with the venting and flaring of natural gas pits, as they can be present in oil and gas formations.

Boron removal from metallurgical-grade silicon by CaO–SiO2 slag refining

Boron removal from metallurgical-grade silicon (MG-Si) using CaO–SiO2 slag was studied by employing a medium-frequency electromagnetic induction furnace. The relationship between the optical basicity (Λ) of the CaO–SiO2 slag and the distribution coefficient of boron (LB) was investigated. Consequently, the local minimum and maximum LB values of 0.72 and 1.58 are obtained when Λ = 0.56 and Λ = 0.71, respectively. The boron content in MG-Si decreases gradually with refinement time increasing, down to a minimum value of 4.73 × 10−6. The controlling step in the removal of boron from MG-Si is not the chemical reaction at the interface of the slag and silicon. Instead, the controlling step is a diffusion mass transfer, in which boron impurities diffuse from molten silicon to the interface of the slag and silicon, or B2O3 formed by the chemical reaction diffuses from the slag–silicon interface to molten slag.

Determination of metal contact recombination parameters for silicon wafer solar cells by photoluminescence imaging

In order to reliably extract metal–silicon interface recombination parameters to aid optimization of silicon wafer solar cell designs, a test metallization pattern with regions of varying front metal contact fractions is screen printed to create special test cells, alongside solar cells with a standard H-pattern print. Both the test pattern and H-pattern cells are analyzed using intensity-dependent photoluminescence imaging (Suns-PL), and the H-pattern cells are additionally probed at each busbar to monitor their open-circuit voltage (via Suns-Voc measurements). The resultant data are analyzed in two ways, the first being a simple four parameter graphical fitting to the Suns-PL plots of the regions of interest, and the second being a detailed finite element method (FEM) based simulation and numerical fitting. By accounting for the lateral balancing currents in the FEM based simulation, test patterns with imaginary isolation across the edges of the mini cells could be used, which were the easiest to fabricate. The FEM method is more rigorous and is able to replicate simultaneously the Suns-PL characteristics of both test pattern and H pattern cells, using a common set of recombination parameters.

Micro-mixer device with deep channels in silicon using modified RIE process: fabrication, packaging and characterization

In the present work, silicon based micromixer microfluidic devices have been fabricated in silicon substrates of 2-inch diameter. These devices are of 2-input and 1-output port configuration bearing channel depth in the range 80---280 µm. Conventional reactive ion etching (RIE) process used in integrated circuit fabrication was modified to get reasonably high silicon etch rate (~1.2 µm/min). It was anticipated that devices with channel depth in excess of 150 µm would become weak and susceptible to breakage. For such devices, a bonded pair of silicon having a 0.5 µm SiO2 at the bonded interface was used as the starting substrate. The processed silicon wafer bearing channels was anodically bonded to a Corning® 7740 glass plate of identical size for fluid confinement. Through-holes for input/output ports were made either in Si substrate or in glass plate before carrying out anodic bonding. Micro-channels were characterized using stylus and optical profiler. Surface roughness of the channel was observed to increase with increasing channel depth. The devices were packaged in a polycarbonate housing and pressure drop versus flow rate measurements were carried out. Reynolds number and friction factor were calculated for devices with 82 µm deep channels. It was observed that up to 25 sccm of gas and 10 ml/min of liquid, the flow was laminar in nature. It is envisaged that using bonded silicon wafer pair and combination of RIE and wet etching, it is possible to get an etch stop at the SiO2 layer of the bonded silicon interface with much smaller value of surface roughness rendering smooth channel surface.

Electron-phonon coupling and thermal conductance at a metal-semiconductor interface: First-principles analysis

The mechanism of heat transfer and the contribution of electron-phonon coupling to thermal conductance of a metal-semiconductor interface remains unclear in the present literature. We report ab initio simulations of a technologically important titanium silicide (metal)–silicon (semiconductor) interface to estimate the Schottky barrier height, and the strength of electron-phonon and phonon-phonon heat transfer across the interface. The electron and phonon dispersion relations of TiSi2 with C49 structure and the TiSi2-Si interface are obtained using first-principles calculations within the density functional theory framework. These are used to estimate electron-phonon linewidths and the associated Eliashberg function that quantifies coupling. We show that the coupling strength of electrons with interfacial phonon modes is of the same order of magnitude as coupling of electrons to phonon modes in the bulk metal, and its contribution to electron-phonon interfacial conductance is comparable to the harmonic phonon-phonon conductance across the interface.

Influence of Ge Ion Implantation into Silicon Dioxide/Silicon Structure on Charge Accumulation under Low–Energy Stationary Radiation

Results on the influence of Ge ion implantation into pyrogenic SiO2 on radiation charge accumulation are presented. Ge embedding in the silicon dioxide/ silicon system has been analyzed theoretically. We show that Ge ion embedding in the stoichiometric silicon dioxide at the silicon dioxide/ silicon interface or forming Ge nanoclusters in the SiO2 bulk provide an energetic advantage.

Temperature-dependent current–voltage measurements of Au/C9H7N/p-Si: Characterization of a metal–organic-semiconductor device

The attachment of organic molecules onto the silicon surfaces is of crucial interest for the development of nanoscale organic–inorganic hybrid materials. In this study, the electrografting of diazonium salts has been used for covalent attachment of the molecules to H-passivated silicon (100) surface. The modification of silicon electrodes with quinoline molecules was carried out through electrochemical reduction of in situ generated diazonium salts from 6-aminoquinoline, and thus an Au/quinoline/p-Si device was fabricated. The results measured from the as-deposited device displayed a higher barrier height at room temperature due to the formation of an interfacial dipole at a metal/organic interface during electrochemical deposition. It has been shown that the barrier height value was increased with the increasing temperature. In addition, there were seen two different behaviours of the temperature-dependent ideality factor and this was attributed to the response of quinoline to temperature below and above 160K such it is likely to take place phase change at the interface. Such a temperature dependence of the barrier height was explained by the Gaussian distribution of the barrier heights due to the barrier height inhomogeneities at the quinoline film/p-type silicon interface. The mean barrier height and the standard deviation σ values were determined as 0.87eV and 0.0989V, respectively. Furthermore, the Norde model was also used for determining the temperature-dependent of barrier height and it was seen that there was a good agreement between that of the common ln(I)–V and Norde model.

A comparative analysis of different measurement techniques to monitor metal and organic contamination in silicon device processing

A few key techniques for the analysis of contamination in silicon are compared for their ability to detect different impurities. Both metal and organic contamination is included in this study. In addition, common contaminants and elements recently introduced in the fabrication process are considered. For what concerns metal contamination, it is shown that different approaches are required depending on the in-depth distribution of the contaminant and hence on its diffusivity. Copper, iron, molybdenum, and tellurium are chosen as examples of contaminants with different diffusivity and solubility properties. Total reflection X-ray fluorescence (TXRF), recombination and generation lifetime measurement techniques, deep level transient spectroscopy (DLTS) and capacitance versus voltage measurements are compared. The detection of slow diffusers is found to be very critical, because a very low dose may result in a non-negligible concentration in the device region. As a consequence, the sensitivity per unit area required for these elements is difficult to reach with surface techniques such as TXRF. On the other hand, very fast diffusers such as copper can hardly be revealed in the solid solution in silicon. Copper in silicon can be revealed at the oxide–silicon interface by TOF-SIMS measurements, or by surface generation velocity measurements with the Zerbst method. For what concerns organic contamination, surface recombination velocity and gate oxide integrity tests were compared. The most relevant effects of organic contamination were observed by electrical stress of the oxide. Indeed, the fraction of capacitors with degraded breakdown voltage increased dramatically in wafers with intentional organic contamination.

Formation of nanostructured Group IIA metal activated sensors: The transformation of Group IIA metal compound sites

Trends in the Group IIA metal oxides and hydroxides of magnesium, calcium, and barium are unique in the periodic table. In this study we find that they display novel trends as decorating nanostructures for extrinsic semiconductor interfaces. The Group IIA metal ions are strong Lewis acids. We form these M2+ ions in aqueous solution and bring these solutions in contact with a porous silicon interface to form interfaces for conductometric measurements. Observed responses are consistent with the formation of MgO whereas the heavier elements display behaviors which suggest the effect of their more basic nature. Mg(OH)2, when formed, represents a weak base whereas the heavier metal hydroxides of Ca, Sr, and Ba are strong bases. However, the hydroxides tend to give up hydrogen and act as Brönsted acids. For the latter elements, the reversible interaction response of nanostructures deposited to the porous silicon (PS) interface is modified, as the formation of more basic sites appears to compete with M2+ Lewis acidity and hydroxide Brönsted acidity. Mg2+ forms an interface whose response to the analytes NH3 and NO is consistent with MgO and well explained by the recently developing Inverse Hard/Soft Acid/Base model. The behavior of the Ca2+ and Ba2+ decorated interfaces as they interact with the hard base NH3 follows a reversal of the model, indicating a decrease in acidic character as the observed conductometric response suggests the interaction with hydroxyl groups. A change from oxide-like to hydroxide-like constituents is supported by XPS studies. The changes in conductometric response is easily monitored in contrast to changes associated with the Group IIA oxides and hydroxides observed in XPS, EDAX, IR, and NMR measurements.

Sensitive and selective detection of H2S and application in the presence of toluene, benzene, and xylene

We study the conductometric response to H2S in the range from 0.6 to 100ppm using nanostructure metal oxide decorated interfaces and demonstrate the highly selective detection of H2S in the presence of the BTEX contaminants toluene, benzene, and xylene. We evaluate the response to H2S of a porous silicon (PS) interface and this interface decorated with TiO2, SnOx, NiO, and AuxO (x≫1) nanostructured deposits. The response of an AuxO decorated interface dominates those of TiO2 and SnOx, which dominate NiO. All of the decorated interfaces show a considerable enhancement of response relative to PS. The observed responses are consistent with the recently developing IHSAB principle and the observed enhancements well exceed those for other analytes. Sensor rejuvenation and the ability to deal with highly humid environments are evaluated. SnOx decorated PS is found to be highly selective for H2S with selectivity ratios well in excess of 104:1 for toluene and benzene, and well in excess of 103:1 for xylene, all of which act as weak bases. The dominance of the response for H2S relative to the BTEX aromatics toluene, benzene, and xylene has important implications for the monitoring of significant contaminants associated with the venting and flaring of natural gas pits as they are present in oil and gas formations.

Calculation of Modal Contributions to Heat Transfer across Si/Ge Interfaces

ABSTRACTUsing our newly proposed interface conductance modal analysis (ICMA) formalism, we study the modal contributions to thermal interface conductance (G ) across the interface of crystalline silicon and crystalline germanium. We present the accumulation functions of G at different temperatures and predict G as a function of temperature after proper quantum-corrections have been applied. Different classes of vibration are identified across the interface, among which interfacial modes are determined to have the highest per mode contribution to G . The results demonstrate the ability of ICMA in not only calculating the spectral contributions to G but exactly pinpointing the shape of each vibrational eigen state.

Neutron Reflectometry to Measure In Situ Li Permeation through Ultrathin Silicon Layers and Interfaces

High-intensity specular neutron reflectometry was used to measure atomic transport processes in the solid state in-situ. As a model system, Li transport through ultrathin amorphous silicon layers (5 nm) and adjacent lithium silicate interfaces relevant for battery applications is studied. For the experiments a multilayer structure consisting of five [Si/natLiNbO3/Si/6LiNbO3] units was investigated, which was produced by ion beam sputtering. LiNbO3 is solely used as a tracer reservoir. Thin lithium silicate layers are formed at Si/LiNbO3 interfaces during sputtering. Two types of Bragg peaks are detectable in the neutron reflectivity pattern. One originates from the double layer periodicity introduced by the LiNbO3/Si chemical contrast, the other from the four-layer periodicity introduced by the Li isotope contrast of the natLiNbO3 and 6LiNbO3 layers. If the multilayer arrangement is annealed at 240°C, Li diffusion through the silicon layer between the two isotope reservoirs is induced and only the Bragg peak due to Li isotope contrast variation is reduced, while the peak due to chemical contrast variation remains constant. High-intensity specular neutron reflectometry allows to record reflectivity patterns within some minutes, which is the base for continuous in-situ measurements during annealing. Simulation tools allow to derive the Li permeability (diffusivity x solubility) in silicon.

Adherence Study of Diamond-Like Carbon Films Deposited on X45 CrSi 9-3 Steel with a Silicon Interlayer

The martensitic stainless steel X45CrSi93 is widely used in the automotive industry. One way to improve its properties is the deposition of high adhesiveness DLC films, which are well known for their excellent properties such as high hardness, low friction coefficient, chemical inertness, biocompatibility and excellent wear resistance. In this work, the adhesion between substrate and film was studied, by growing silicon interfaces with different deposition parameters. The technique used for growing these films was PECVD pulsed-DC. In order to obtain information of the silicon interface formation, ionic sub-implantation simulations were performed, by the software SRIM/TRIM. Raman spectroscopy was used to verify the atomic structure of the films. Scratch tribological test was performed to study adhesion. It was observed that the mechanical and tribological properties were greatly improved with the deposition of DLC films on the silicon interface. A correlation between the residual stress and adhesion of DLC films was found.

InGaN/silicon heterojunction based narrow band near-infrared detector

While InGaN devices have shown great potential as photodetectors and light emitting devices in the UV to visible range, extension of their applications to the near-infrared (NIR) region has been less successful due to challenges faced in developing high Indium content InGaN layers. Here, the authors present our results on the development of an InGaN/Silicon heterojunction structure with a &amp;gt; 70% In content in the InGaN layer, showing a measurable response in the NIR range. The achieved results show that the band offset between InGaN, buffer layer and Silicon interface can be used as a mean for fabrication of photodiode structures with spectral sensitivity varying with indium content. However, the authors observed that the resulting photoresponse is still a combination of photoresponses produced by absorption of photons in both InGaN and silicon materials.