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Formation of uniaxial strained Ge via control of dislocation alignment in Si/Ge heterostructures
摘要： Uniaxially strained Ge/SiGe heterostructures are fabricated by selective ion implantation technique, where dislocation alignments are highly controlled by the local defect introduction. Firstly, ion-implantation-defects are selectively induced into a Ge substrate, followed by the growth of a SiGe buffer layer. As a result, the SiGe on the implanted region is largely strain-relaxed due to the defects acting as dislocation sources. In contrast, it is demonstrated that anisotropic strain relaxation takes place in the SiGe on the unimplanted region, leading to the uniaxial strained SiGe. A strained Ge layer is pseudomorphically grown on the SiGe buffer and the same strain states are observed for the Ge layer. It is found that mis?t dislocations generated at the interface between the SiGe layer and the Ge substrate are aligned along only one direction. These one-directional dislocations are an origin of the uniaxial strain relaxation. Moreover, effects of ion-implantation stripe-pattern widths on the strain states are investigated. With the implanted line width increasing, the anisotropy of the strain in the unimplanted region is enhanced. From these results, it can be said that this technique opens a route to engineer dislocation alignments and anisotropic strain in semiconductor hetero structures toward high performance novel devices.
关键词： dislocation alignment,uniaxial strained Ge,Si/Ge heterostructures,selective ion implantation,anisotropic strain relaxation
更新于2025-09-10 09:29:36
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Inducing defects in 3.3 kV SiC MOSFETs by annealing after ion implantation and evaluating their effect on bipolar degradation of the MOSFETs
摘要： Process-induced basal plane dislocations (BPDs) formed by annealing after aluminum ion implantation were investigated, and their effect on the bipolar degradation of body diodes in 3.3 kV SiC MOSFETs was evaluated. Contact resistance in the p+ region decreases with ion dose but increases with implantation temperature due to the formation of the recrystallized layer at SiC surface and difference of acceptor activation rates in high and low temperature implantation. In the case of high ion dose implantation at room temperature, contact resistance was of 1.3×10?3 Ωcm2. However, process-induced BPDs formed with high ion dose implantation at room temperature, and could be suppressed with low ion dose or high implantation temperature. They were formed after activation annealing, and expanded to form stacking faults (SFs) under both continuous irradiation from a Hg lamp and current stress. Bipolar degradation occurred in the case of MOSFETs fabricated using high ion dose implantation at room temperature, but was not observed in the case of either low ion dose or high implantation temperature. The activation energy for SF expansion velocity in the ?1–100? direction was estimated to be 0.20 eV at a forward current density of 125 A cm?2. Moreover, the results of a long duration current stress test with high current density and high junction temperature indicate that low ion dose or high implantation temperature can suppress the formation of process-induced BPDs. MOSFETs fabricated using optimized ion implantation conditions show high reliability under bipolar operation.
关键词： MOSFET,bipolar degradation,stacking fault,contact resistance,basal plane dislocation,SiC,ion implantation
更新于2025-09-09 09:28:46
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Current Aperture Vertical β-Ga2O3 MOSFETs Fabricated by N- and Si-Ion Implantation Doping
摘要： Depletion-mode vertical Ga2O3 metal-oxide-semiconductor field-effect transistors featuring a current aperture were developed on a halide vapor phase epitaxial drift layer grown on a bulk β-Ga2O3 (001) substrate. Three ion implantation steps were employed to fabricate the n++ source regions, lateral n channel, and p current blocking layers, where Si and N were selected as the donor and deep acceptor dopant species, respectively. The transistors delivered a drain current density of 0.42 kA/cm2, a specific on-resistance of 31.5 m?·cm2, and an output current on/off ratio of over 108. High-voltage performance of the present devices was hampered by a large gate oxide field in the off-state causing high gate leakage, a limitation that can be readily overcome through optimized doping schemes and an improved gate dielectric. The demonstration of a planar-gate vertical Ga2O3 transistor based on a highly manufacturable all-ion-implanted process greatly enhances the prospects for Ga2O3-based power electronics.
关键词： vertical transistor,power MOSFET,ion implantation,Ga2O3,current aperture
更新于2025-09-09 09:28:46
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Nanostructured Titanium Dioxide Based on Titanium Alloys: Synthesis and Properties
摘要： Titanium dioxide (TiO2) has provoked a significant amount of scientific and technological interest due to their anticipated impact in the fields of photocatalysis, solar cells, lithium-ion battery electrodes, and biomedical devices. This is particularly apparent in the case of anodization and ion implantation for modifying Ti-based alloys. However, the lack of sufficient solar light absorption and limited hole diffusion significantly affect the performance of TiO2 in photocatalysis. Moreover, the biocompatibility and corrosion resistance of Ti-based biomedical device need to be enhanced to achieve a longer service life. In the present review, the MOx prepared by anodization is described first. Then, the electrolyte parameters during anodization are assessed by comparing various electrolytes including ethylene glycol, glycerol, formamide, and aqueous electrolytes. Additionally, the effects of ion implantation on the surface of Ti-based alloy are outlined. By analyzing the impact on various synthetic method and modification strategies of nanostructured TiO2, the essential elements of suitable in situ doping ratio and ion implantation dose are addressed. Finally, the outlook for anodization and ion implantation for constructing nanostructured TiO2 is discussed, highlighting challenges and key areas for future research and development.
关键词： Anodization,Water Splitting,Biocompatibility,TiO2-Based Ti Alloy,Ion Implantation
更新于2025-09-09 09:28:46
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Epitaxial Ge-rich silicon layers after dry oxidation of Ge implanted silicon
摘要： We report on formation of epi-layer of SixGe1-x by taking standard procedure in CMOS technology. The competitive process of solid solubility of Ge dopant into Si and SiO2 is the key to engineer atomically sharp, low defect very thin epitaxial layer at the interface of oxide-Si. Oxidation time process was used to control the distribution of the doped Ge ions at the interface of Si with oxide and in the oxide layer. Implanted samples (35 keV and 1 × 1016 Ge+/cm2) were oxidized at 1050 °C for 30–90 min. RBS-Channeling analysis shows two separate peaks of Ge corresponds to different depths after oxidation. Corroborate with high resolution microscopy and elemental analysis, we determined the first peak as enriched layer of SixGe1-x at the interface of SiO2eSi. Less than 10 nm epitaxially grown interfacial layer is very low in defects, and Ge ions are fully substituted into the host lattice. The second peak originated from diffusion of Ge into SiO2 resulted in a segregated layer containing Ge in oxide film. Technological demand on forming SixGe1-x layer for CMOS application through standard routes is what we address in this research.
关键词： High resolution electron microscopy,Point defects,Germanium silicon alloys,Ion implantation,Solid phase epitaxy
更新于2025-09-09 09:28:46
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Influence of low energy (keV) negative Li ion implantation on properties of electrochemically induced scaffold-based growth of PbSe nanowires
摘要： In the present work, PbSe nanowires were synthesized using restrictive template-based electrodeposition technique and implanted under vacuum with 200 keV negative Li ion at different fluences. The morphology of the nanowires was characterized by field emission scanning electron microscopy (FESEM). X-ray diffraction patterns confirmed the same crystal structure for pristine and ion implanted samples besides change in intensity of diffraction peaks were observed. Crystallite size was evaluated using modified Scherrer method and Williamson–Hall methods (UDM and USDM). Stress, strain, stacking fault, dislocation density and lattice parameters were evaluated for the pristine and ion implanted samples. UV–Vis spectroscopy results showed decrease in optical bandgap with increasing ion fluence. Photoluminescence spectra manifested decrease in emission peak with increasing ion fluence. The I–V graphs of the nanowires depicted space charge limiting current (SCLC) characteristics at higher voltage. An increase in current was observed with increase in ion fluence due to increase in free charge carriers.
关键词： PbSe nanowires,Negative Li ion implantation,Electrical properties,Structural properties,Optical properties,Electrodeposition
更新于2025-09-04 15:30:14
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[IEEE 2018 IEEE Research and Applications of Photonics In Defense Conference (RAPID) - Miramar Beach, FL (2018.8.22-2018.8.24)] 2018 IEEE Research and Applications of Photonics In Defense Conference (RAPID) - Electrical and Structural Characterization of Si Implanted Homoepitaxially Grown AlN
摘要： AlN is an attractive material for UV optoelectronics and high-power device applications; however, obtaining high n-type conductivity is still a challenge. Ion implantation may provide an avenue to realize electrical conductivities suitable for device operation. A novel annealing procedure to recover lattice damage is presented.
关键词： damage and recovery,annealing,ion implantation
更新于2025-09-04 15:30:14
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Ohmic graphite-metal contacts on oxygen-terminated lightly boron-doped CVD monocrystalline diamond
摘要： A process to obtain ohmic contacts on oxygen-terminated lightly boron-doped CVD monocrystalline diamond films was developed. Samples were contacted by Ti/Au metallic pads in the transmission line model (TLM) configuration. The electric contacts were placed onto a mesa structure produced on the CVD boron-doped layer. One of the samples was additionally implanted with helium ions at 10 keV in order to induce the formation of a graphitic layer underneath the diamond surface before contacting so as to improve electrical conduction. The electrical performance of both devices was characterized by the TLM method and compared. As a result, the sample with metallic electrodes exhibited a small and non-linear electrical conduction, while the graphitic/metallic contacts showed an ohmic behaviour with an estimated specific contact resistance as low as 3.3 × 10-4 Ω.cm2 for a doping level of a few 1017 cm-3. This approach opens the way to more efficient ohmic contacts on intrinsic or low-doped diamond that are crucial for the development of electronic devices and detectors.
关键词： oxygen terminations,graphitization,Ohmic graphite-metal contacts,lightly boron-doped CVD diamond film,ion implantation
更新于2025-09-04 15:30:14