Boron Implantation Research Articles

Dose-Dependent Performance of Boron-Implanted Self-Aligned Bottom-Gate IGZO TFTs

This work provides an interpretation of donor activation in self-aligned bottom-gate (SA-BG) Indium-Gallium-Zinc Oxide (IGZO) TFTs with ion-implantation of boron (11B+) species as the source/drain treatment. The effect of implant dose on device operation was investigated. Transfer characteristics appeared similar with a boron dose of 1 and 2×1015 cm-2 however, a 45% decrease in max current was observed for devices implanted with a 4×1015 cm-2 dose. Van der Pauw measurements displayed a similar trend; an increase in boron dose resulted in an increase in sheet resistance. A left-shift in transfer characteristics was observed with a greater shift in the 4×1015 cm-2 dose devices, following thermal stability treatments. The existence of two separate boron species is hypothesized, (1) an electrically active donor species involving a relatively small fraction of the total boron concentration and (2) additional boron interstitials and/or other associated defects. A detailed discussion on developed arguments arrived at through analysis of TFT electrical characteristics is presented.

Complex Diagnostics of Silicon-on-Insulator Layers after Ion Implantation and Annealing

A technology was developed for activating ion-implanted dopants in silicon-on-insulator layers at a low annealing temperature (600°C) using the pre-amorphization technique of a silicon device layer. In the case of phosphorus implantation, silicon was amorphized directly by dopant ions. In the case of boron implantation for pre-amorphization, the layers were preliminary irradiated with argon or fluorine ions. Complex diagnostics of the implanted layers was carried out using secondary ion mass spectrometry, X-ray diffractometry and small-angle X-ray reflectometry. The combination of methods made it possible to characterize the impurity distribution, the degree of silicon crystallinity, the layer thicknesses, and the interface widths in structures. The results of diagnostics of the structure and composition correlate well with calculations in the SRIM software package and the electrophysical characteristics of the layers after annealing. It was shown that the use of argon for pre-amorphization of silicon interfered with the recrystallization process and did not make it possible to achieve acceptable electrical characteristics of the doped layer. Amorphization with phosphorus and pre-amorphization with fluorine during boron implantation allowed obtaining the required values of the resistance of the doped layers after annealing at a temperature of 600°C. The use of a complex approach made it possible to optimize the modes of amorphization, ion doping, and annealing of silicon-on-insulator structures at low temperatures, necessary for the creation of light-emitting device structures based on silicon-germanium nanoislands.

Characterization of a HPHT boron ion-implanted diamond X-ray mirror following high vacuum annealing

The incorporation of boron into a diamond lattice holds the potential to advance X-ray optics, offering the capability to manipulate various parameters of the lattice. This includes enhancing near-infrared absorption relative to pure diamond, thereby enabling Q-switchable optics. The use of MeV boron implantation emerges as a promising method for precisely doping the diamond lattice. However, for these optics to function effectively as Bragg-reflecting mirrors, ion implantation must be executed with meticulous attention to maintaining a strain-free, perfect diamond lattice. This study aimed to investigate the feasibility of utilizing a 9 MeV ion beam for high energy boron implantation. Different areas of a high-pressure, high-temperature (HPHT) diamond sample were subjected to irradiation with 9 MeV Boron ions, ranging in fluences from 5×1015 to 2.5×1016ions/cm2. Following boron implantation, high-temperature vacuum annealing was performed to restore the diamond lattice. Our assessment utilized X-ray rocking curve imaging, surface profilometry, and micro-Raman spectroscopy, with additional observations on near-infrared transmission properties. Our measurement of high-quality Bragg reflection through X-ray rocking curve imaging, sensitive to implantation-induced strain and defects, served as an key diagnostic for the effectiveness of this ion-implanted sample as a Bragg-reflecting optic.

Turning the optical properties of microcrystalline diamond films by boron ion implantation and annealing

We investigated the correlation between microstructures and optical properties of boron ion implanted microcrystalline diamond (B-MCD) thin films annealed at different temperatures. Ellipsometry characterization of B-MCD films was performed in the wavelength range of 380–1000 nm and the disperse parameters of the films such as single oscillator energy and dispersive energy were uniquely determined by using a Gaussian model. The results show that the refractive index increases from 2.18 to 2.21 to 2.28–2.29 with annealing temperature increasing from 700 to 800 °C and then it slightly decreases to 2.25–2.28 with annealing temperature further increasing to 900 °C, implying that the annealing temperature has a significant impact on the optical properties of B-MCD films. Raman spectra reveal that the full width at half maximum of diamond peak significantly decreases after 800 °C annealing, indicating a better quality of diamond crystalline. X-ray photoelectron spectroscopy results show that this sample contains higher sp3 carbon content, lower sp2 and C–O contents on the film surface after 800 °C annealing, implying that fewer defects exist. The results are of great significance for the preparation of excellent boron ion implanted microcrystalline diamond for waveguide based Mach-Zehnder Interferometer liquid sensing.

Temperature-induced disruptive growth rate behavior due to streaming instability in semiconductor quantum plasma with nanoparticles

The nature of the growth rate due to streaming instability in a semiconductor quantum plasma implanted with nanoparticles has been analyzed using the quantum hydrodynamic model. In this study, the intriguing effect of temperature, beam electron speed, and electron-hole density on growth rate and frequency is investigated. The results show that the growth rate demonstrates a nonlinear behavior, strongly linked to the boron implantation, beam electron streaming speed and quantum correction factor. A noteworthy finding in this work is the discontinuous nature of the growth rate of streaming instability in boron implanted semiconducting plasma system. The implantation leads to a gap in the growth rate which further gets enhanced upon increase in concentration of implantation. This behavior is apparent only for a specific range of the ratio of thermal speed of the electrons to that of the holes.

Growth of synthetic diamond films and their electrophysical properties

The possibilities of formation of single-crystal homoepitaxial diamond structures grown by the method of vapor-phase chemical deposition are investigated. Optimal technological conditions for the formation of structures are suggested. The layer with p-type conductivity formation process depending on the temperature and time is determined. It was shown that applied thermal treatment method in hydrogen can be an alternative to the conventional method of H layer formation in microwave hydrogen plasma due to simpler and more reproducible. The profile distribution of boron atoms in a diamond crystal was determined under different implantation modes. The temperature dependence of specific conductivity in the temperature range 80–700 K was studied, and the activation energy was calculated. The results of Hall measurements of the electrophysical parameters of implanted samples are presented, and the effect of nitrogen concentration on the electrophysical parameters is revealed. The electrophysical parameters of the structures obtained under various modes of ion implantation of boron in a crystal and subsequent annealing are presented. The possibility of creating a field effect transistor on a hydrogenated diamond surface is shown. The current-voltage characteristic of the manufactured sample was studied and it was shown that it demonstrates low leakage through the gate.

Evaluating diffusion barriers of defects in boron ion implanted diamond

The potential of diamond for electronic materials can be realized by creating well-controlled p- or n-type doping profiles. p-type doping is achieved by ion implantation of boron followed by high temperature annealing to relax the lattice, reduce the defects and create active dopant sites by allowing diffusion of defects in the diamond crystal. It has been found that even after this diffusion the percentage of active dopant sites after high temperature annealing are only a small fraction of the total doping. We perform first principles density functional theory calculations and estimate the migration barrier energy (MBE) for diffusion of carbon vacancies, hydrogen, boron and their complexes in diamond including the boron‑carbon vacancy complex which was recently observed and predicted as a color center for qubit realization. These defects are commonly found after ion implantation of boron in diamond. Here, we use nudged elastic band (NEB) technique to estimate the MBE for these defects and use it to predict the corresponding annealing temperature. Our calculations correctly predict the MBE for carbon vacancy as compared to the available references in literature and extend the calculation to other defects predicted in ion implanted diamond. Our objective of evaluating the MBE is to predict the diffusion processes occurring during post-implantation annealing of diamond.

Elastic backscattering during boron implantation in Si1-xGex

We have investigated the elastic backscattering which occurs during ion implantation, and its impact on the retained implantation dose. A series of Si1-xGex (0 ≤ x ≤ 1) alloy films were implanted with 5 × 1014 atoms/cm2 of 11B at an energy of 10 keV. Nuclear reaction analysis (NRA) was used to characterize the retained boron dose within the Si1-xGex (0 ≤ x ≤ 1) samples by means of the 11B(p,α1)2α12 nuclear reaction. The experimental results show that the elastic backscattering effect is significant in this case, with the retained boron dose decreasing linearly as the target matrix varies from pure silicon to pure germanium. Our findings are in good agreement with simulations carried out using the SRIM-2013 software. Our study indicates that the backscattering effect during implantation must be accounted for when a specific concentration is targeted, or when adopting an implanted film as a reference standard, for example, in secondary ion mass spectrometry.

Comparative study on the second-harmonic generation of thermally poled fused silica by multi-energy boron and argon ion implantations

The second-order optical nonlinearity (SON) of thermally poled fused silica was shown for the first time to be significantly improved by the implantation of multi-energy boron (B) ions, and the outcomes were compared with those obtained from the implantation of multi-energy argon (Ar) ions. Second-harmonic (SH) signals in both samples grew roughly linearly as the poling temperature rose. Samples with Ar implants showed a greater increase in SH signal with rising poling temperature. A qualitative explanation for the formation of [Formula: see text] in poled samples can be found in a model of charge hopping and migration through defects. The diminished SH signal in the B-implanted sample is probably caused by the negative charge trapping layer, as well as by B[Formula: see text] and E[Formula: see text] center defects.

Optimization of Activation Annealing Condition for Boron‐Implanted Diamond

Impurity activation of dopants implanted in diamond is one of the crucial issues for device application of diamond. Boron impurity atoms are introduced in diamond, which expectedly act as acceptors, by ion implantation technique, and are investigated the optimum annealing time for the effective dopant activation. The impurity doping is performed by boron ion implantation at multiple incident energies to obtain a uniform dopant concentration from the surface to 350 nm depth followed by activation annealing at 1300 °C for 5–240 min. The electrical properties of specific resistance, carrier concentration, and conduction type are analyzed as a function of temperature from room temperature to 873 K. The estimated ionization energy is strongly dependent on the annealing time and asymptotically approaches to 0.3 eV, which is theoretically expected ionization energy of acceptor boron, with increasing annealing time. A shorter annealing time ( does not sufficiently recover radiation damages caused by ion implantation forming deep levels, which act as irregular conduction. It is consequently found that an optimum window of annealing time for effective dopant activation and suggested carrier transport mechanisms depending on the annealing time.

Influence of Structural Defects on the Electrophysical Parameters of pin-Photodiodes

The results of studies of electrophysical parameters of pin-silicon-based photodiodes, depending on their operating modes (external bias and temperature), manufactured on single-crystal silicon wafers of p-type conduction orientation (100) with ρ = 1000 ohm cm, are presented. The p+-type region (isotype junction) is created by the implantation of boron ions; the n+-type region, by the diffusion of phosphorus from the gas phase. It is established that on the voltage-current characteristics under reverse bias, three regions of dark cur-rent variation depending on the applied voltage can be distinguished, sublinear, superlinear, and linear, caused by various mechanisms of the generation-recombination processes in the depletion region of the pn-junction. A noticeable dependence of the barrier capacitance value (at a frequency of 1 kHz) and the size of the depletion region on temperature is observed only when the applied reverse voltages do not exceed the contact potential difference (V ≤ 1 V).

Role of Boron in Assisting the Super-Enhancement of Emissions from Carbon-Implanted Silicon.

The super enhancement of silicon band edge luminescence when co-implanted with boron and carbon is reported. The role of boron in the band edge emissions in silicon was investigated by deliberately introducing defects into the lattice structures. We aimed to increase the light emission intensity from silicon by boron implantation, leading to the formation of dislocation loops between the lattice structures. The silicon samples were doped with a high concentration of carbon before boron implantation and then annealed at a high temperature to activate the dopants into substitutional lattice sites. Photoluminescence (PL) measurements were performed to observe the emissions at the near-infrared region. The temperatures were varied from 10 K to 100 K to study the effect of temperature on the peak luminescence intensity. Two main peaks could be seen at ~1112 and 1170 nm by observing the PL spectra. The intensities shown by both peaks in the samples incorporated with boron are significantly higher than those in pristine silicon samples, and the highest intensity in the former was 600 times greater than that in the latter. Transmission electron microscopy (TEM) was used to study the structure of post-implant and post-anneal silicon sample. The dislocation loops were observed in the sample. Through a technique compatible with mature silicon processing technology, the results of this study will greatly contribute to the development of all Si-based photonic systems and quantum technologies.

Influence of boron implantation induced defects on solar cells: Modeling the process defects

The effect of process-induced defects on the photo-generated charge-carrier lifetime and solar cell performance is critical, which will help optimize the process recipe. In this work, we attempt to quantify the effects of process-induced defects during boron implantation on the n-type silicon wafer in different annealing ambiences. We have evaluated the role of defects that can be formed during oxygen and inert ambience annealing on n-type bifacial passivated emitter rear totally diffused solar cells using a recombination current prefactor (J0). The numerically calculated J0 is calibrated with the reported experimental J0 values using two different methods: (i) Shockley–Read–Hall lifetime and (ii) effective trap-density method. In the latter method, we used the simulated defect density profiles. Both methods capture the process-induced degradation. We observed that the process-induced defects could deteriorate by almost 1% absolute efficiency for the considered annealing conditions. We found that dislocation loops alone cause an ignorable effect on terminal characteristics, but other process-induced mechanisms could dominantly degrade the cell's performance. To further support, we show that independent defects (apart from coupled defects) other than dislocation loops could explain the experimentally reported boron-implanted diodes’ J–V curves under reverse bias conditions.

Structural disorder and distribution of impurity atoms in β-Ga2O3 under boron ion implantation

Gallium oxide (Ga2O3) has recently attracted much attention due to the prospect of its application in power electronics and in other areas. An important task is the development of controlled and reproducible methods for doping this material with various impurities, among which boron is of considerable interest. The regularities of Ga2O3 doping with this isovalent (for Ga) impurity are poorly studied. Even for ion implantation as the most common semiconductor doping method these studies are still at the initial stage. In this work, the structural properties of β-Ga2O3 layers upon boron ion irradiation and subsequent annealing have been studied using X-ray Diffraction, Reflection High-Energy Electron Diffraction, Secondary Ion Mass Spectrometry, as well as theoretical calculations from first principles. Among the most interesting results are the establishment of a strong redistribution of implanted boron during post-implantation annealing and the conclusion about low degree of substitution of gallium sites by boron atoms.

Boron and orthopedic implants: A review of the literature

A material created to interact with biological systems to enhance, treat or modify a tissue, organ, or body function is called a biomaterial. Sutures, dental fillings, needles, catheters, bone plates, and orthopedic implants are the most commonly used medical biomaterials. With the increasing use of orthopedic implants worldwide, there remains significant interest in developing new technologies to improve the effective clinical performance of contemporary treatment modalities and devices. Biomaterials used in orthopedics often require revision due to problems such as wear, corrosion, and infection. These revisions have become a significant burden for the patient and the healthcare system. Boron, with its unique properties, is an element that has the potential to overcome these problems. Therefore, in recent years, the importance of boron elements in the health field as well as in the industrial field has been noticed, making the use of boron in medicine very popular

A Combination of Ion Implantation and High‐Temperature Annealing: The Origin of the 265 nm Absorption in AlN

The commonly observed absorption around 265 nm in AlN is hampering the outcoupling efficiency of light‐emitting diodes (LEDs) emitting in the UV‐C regime. Carbon impurities in the nitrogen sublattice (CN) of AlN are believed to be the origin of this absorption. A specially tailored experiment using a combination of ion implantation of boron, carbon, and neon with subsequent high‐temperature annealing allows to separate the influence of intrinsic point defects and carbon impurities regarding this absorption. Herein, the presented results reveal the relevance of the intrinsic nitrogen‐vacancy defect VN. This is in contradiction to the established explanation based on CN defects as the defect causing the 265 nm absorption and will be crucial for further UV‐LED improvement. Finally, in this article, a new interpretation of the 265 nm absorption is introduced, which is corroborated by density functional theory (DFT) results from the past decade, which are reviewed and discussed based on the new findings.

(Invited, Digital Presentation) Ion Implantation for Amorphous-InGaZnO Sheet Resistance Control Technique

Amorphous indium-gallium-zinc oxide (a-IGZO) attracts much attention for next-generation flat-panel displays due to the large band gap, visible light transparency, printability, thickness-uniformity and low-temperature in film deposition. Using a-IGZO films, thin-film-transistors (TFTs) are realized, which show superior behavior compared with amorphous Si-based TFT. In order to further improve a-IGZO TFT performance via source-drain resistance reduction, plasma treatment, excimer laser annealing and ion implantation methods as the sheet resistance reduction techniques were investigated. Among them, the ion implantation methods have depth control ability through insulator layers and good verticality.In our previous work we elucidated that a-IGZO sheet resistance reduction can be attributed to oxygen vacancy (Vo) generated by noble gas implantation. However, there is still much room for clarifying and improving the implantation method, since it is difficult to measure the gas itself and vacancies profiles in a-IGZO due to small ionization cross sections and small existence ratio. In addition many injectable ion species in a-IGZO are not investigated in detail.In this work, we carried out one of the conventional ion boron (B+) or noble gas neon ion (Ne+) implantations and investigations in 50-nm-thick a-IGZO film on glass. Electron transport properties of B+ or Ne+ implanted a-IGZO films as a function of the a-IGZO depth were investigated by room temperature Hall measurements combined with wet etchings. In case of Ne+ implanted a-IGZO film, we estimated Vo relation density depth profile consistent with the electron concentration depth profile in a-IGZO and implanted Ne density depth profile, since the Ne itself cannot be a donor. In case of B+ implanted a-IGZO film, the Vo concentration profile is not agreement with electron concentration profile only, but also agreement the B profiles at the deep position in the a-IGZO. On the other hand, bonding analyses by X-ray photoelectron spectroscopy (XPS) were carried out. From the XPS results, we find that Vo increases after the Ne+ implantation in a-IGZO and Boron-Oxygen bonding is dominant for the implanted B+ in a-IGZO, which indicates also that boron itself contribute the a-IGZO resistance reduction. Based on the knowledges obtained by the Hall measurements and the XPS results, we carried out a-IGZO TFT processes with gate length L g = 4-10 um and channel width 10 um via the appropriate ion energies and doses of B+ or Ne+ implantation. The TFTs show off current 10-12 A/mm, on/off ratio ~108 in the case of the both ions from relations between gate voltage and drain current. In addition, we investigated the device scalability. The electrical channel length (L eff) is not the same as the L g, and is determined by the carrier profile at the gate edges. L eff = L g - ΔL is obtained by the transmission line method (TLM). From TLM results, we find that the ΔL < 1 um in case of the B+ implantations and ΔL ~ 1 um in case of the Ne+ implantations. In summary, we elucidated that a-IGZO sheet resistance reduction can be attributed to Vo or boron itself.In addition, a-IGZO TFT processes with the ion implantations were carried out, which indicate good on/off ratios and microfabrication possibilities for industrial application. We expect that the B+ or Ne+ implantations in a-IGZO films are useful as resistance control technique for a-IGZO device processing.This work is supported by Beam and Plasma Technology Laboratories Research and Development Division NISSIN ELECTRIC CO., LTD. in the large number of sample preparations and analyses.

(Invited, Digital Presentation) Ion Implantation for Amorphous-InGaZnO Sheet Resistance Control Technique

As a next-generation electronics material, amorphous-InGaZnO (a-IGZO) film devices were investigated. In order to further utilize a-IGZO films, we carried out conventional ion of boron (B+) or neon (Ne+) implantations in a-IGZO thin films on glass and analyzed the implanted a-IGZO via Hall measurement with wet etching. In addition, a-IGZO thin film transistor processes with the implantation were carried out. As a result, we find that both ions drastically decrease a-IGZO sheet resistances. However, we observed oxygen vacancy area increase in the case of Ne+ implanted a-IGZO in 300 oC post annealing, which indicates Ne diffuses in a-IGZO film. On the other hand, B diffusion was not observed by depth profile comparison between the implanted samples with and without annealing. Furthermore, we extract key device parameters, such as effective channel length and ON/OFF current ratio, which can be applied to a-IGZO device processing.

Distinct junction transformations of pixel-arrayed long-wavelength infrared detectors by photocurrent mapping

Pixel-arrayed long-wavelength HgCdTe is of great significance in the development of infrared detection. However, the PN junction formation process for long-wavelength HgCdTe is complex. The damage induced by boron ion implantation and subsequent low-temperature annealing may results in changes in the effective doping concentration and geometry of the actual n-type implantation region. Therefore, an in-situ, non-destructive scanning-photocurrent-microscopy (SPCM) method is needed to test the performance and electroactive defects of HgCdTe devices. Here, the pixel-arrayed long-wavelength infrared detectors with n-on-p structure formed by B+ ion implantation in Hg vacancy-doped Hg0.78Cd0.22Te crystals were fabricated. The SPCM method is used to characterize the PN junction performance of long-wavelength Hg0.78Cd0.22Te array detectors. It is found that the long-wavelength device transformed from n-on-p structure to n-on-n− structure at about 175 K, and further turns into an n−-on-n-on-n− structure with the temperature increasing. In addition, when the temperature increases, the minority carrier diffusion length in the B+ ion implantation region gradually decreases with the activation of the recombination center. Our work provides an effective theoretical and experimental basis for the HgCdTe junction formation process.

Impact of ion implantation and annealing parameters on bifacial PERC and PERT solar cell performance

Passivated Emitter and Rear Contact (PERC) and Passivated Emitter Rear Totally Diffused (PERT) solar cell designs are now a market reality. In the production of these cells, ion implantation is another method for creating emitters and back surface field (BSF) regions, since it can facilitate the process flow and precise doping control. Here, Technology Computer Aided Design (TCAD) is utilized to assess the effects of ion implantation fluences, annealing temperature, and duration, on the performance of bifacial PERC solar cells. To ensure realistic simulation results, the solar cell model is developed using experimentally demonstrated bifacial counterparts. The process simulation models are also calibrated to match experimentally obtained doping profiles. Simulation results show that by replacing emitter diffusion with phosphorus ion implantation, both the front/rear efficiencies can be improved by 0.07%. The rear boron implantation is also optimized to provide an effective BSF, improving the front/rear efficiencies by 0.21/0.15%, respectively. Moreover, co-annealing of emitter and BSF regions exhibits a 0.2% increase in efficiency than separately annealed PERT cells. Hence an overall improvement of 0.48/0.42% is achieved in the front/rear efficiencies when compared to the original diffused emitter PERC design. The fabrication process sequence is also suggested for these solar cells.