Heteroepitaxial Growth and Heterojunction Characteristics of Voids-Free n-3C-SiC on p-Si(100)

Highly oriented voids-free 3C-SiC heteroepitaxial layers are grown on φ50mm Si (100) substrates by low pressure chemical vapor deposition (LPCVD). The initial stage of carbonization and the surface morphology of carbonization layers of Si(100) are studied using reflection high energy electron diffraction (RHEED) and scanning electron microscopy (SEM). It is shown that the optimized carbonization temperature for the growth of voids-free 3S-SiC on Si (100) substrates is 1100 ℃. The electrical properties of SiC layers are characterized using Van der Pauw method. The I-V, C-V, and the temperature dependence of I-V characteristics in n-3C-SiC-p-Si heterojunctions with AuGeNi and Al electrical pads are investigated. It is shown that the maximum reverse breakdown voltage of the n-3C-SiC-p-Si heterojunction diodes reaches to 220V at room temperature. These results indicate that the SiC/Si heterojunction diode can be used to fabricate the wide bandgap emitter SiC/Si heterojunction bipolar transistors (HBT's).

Numerical Analysis of Steady Current and Temper ature Distributions and Characteristics of Transverse Mode in VCSEL

国家自然科学基金

Microstructural and compositional characteristics of GaN films grown on a ZnO-buffered Si(111) wafer

Polycrystalline GaN thin films have been deposited epitaxially on a ZnO-buffered (111)-oriented Si substrate by molecular beam epitaxy. The microstructural and compositional characteristics of the films were studied by analytical transmission electron microscopy (TEM). A SiO2 amorphous layer about 3.5 nm in thickness between the Si/ZnO interface has been identified by means of spatially resolved electron energy loss spectroscopy. Cross-sectional and plan-view TEM investigations reveal (GaN/ZnO/SiO2/Si) layers exhibiting definite a crystallographic relationship: [111](Si)//[111](ZnO)//[0001](GaN) along the epitaxy direction. GaN films are polycrystalline with nanoscale grains (similar to100 nm in size) grown along [0001] direction with about 20degrees between the (1 (1) over bar 00) planes of adjacent grains. A three-dimensional growth mode for the buffer layer and the film is proposed to explain the formation of the as-grown polycrystalline GaN films and the functionality of the buffer layer. (C) 2004 Elsevier Ltd. All rights reserved.

Photoluminescence characteristics of GaAs/AlGaAs quantum dot arrays fabricated by dry and dry-wet etching

GaAs/AlGaAs quantum dot arrays with different dot sizes made by different fabrication processes were studied in this work. In comparison with the reference quantum well, photoluminescence (PL) spectra from the samples at low temperature have demonstrated that PL peak positions shift to higher energy side due to quantization confinement effects and the blue-shift increases with decreasing dot size, PL linewidths are broadened and intensities are much reduced. It is also found that wet chemical etching after reactive ion etching can improve optical properties of the quantum dot arrays.

The SPER and characteristics of Si1-yCy alloys

\Si1-yCy alloys with carbon composition of 0.5 at.% were successfully grown on n-Si(100) substrate by solid phase epitaxy recraystallization. The result was presented in this paper. With the help of the SiO2 capping layer, rather uniform carbon profile in amorphous Si layer was obtained by dual-energy implantation. Since ion-flow was small and implantation time was long enough, the emergency of beta-SiC was avoided and the dynamic annealing effect was depressed. The pre-amorphization of the Si substrate increased the fraction of the substitutions carbon and the two-step annealing reduced point defects. As a result, Si1-yCy alloys with high quality was recrystallized on Si substrate.

Homoepitaxial growth and device characteristics of SiC on Si-face (0001) 6H-SiC

Homoepitaxial growth of SiC on a Si-face (0 0 0 1) GH-SIC substrate has been performed in a modified gas-source molecular beam epitaxy system with Si2H6 and C2H4 at temperatures ranging 1000 1450 degreesC while keeping a constant SiC ratio (0.7) in the gas phase. X-ray diffraction patterns, Raman scattering measurements. and low-temperature photoluminescence spectra showed single-crystalline SiC. Mesa-type SiC p-n junctions were obtained on these epitaxial layers, and their I-V characteristics are presented. (C) 2001 Elsevier Science B.V. All rights reserved.

Electronic characteristics of InAs self-assembled quantum dots

Deep-level transient spectroscopy and photoluminescence studies have been carried out on structures containing self-assembled InAs quantum dots formed in GaAs matrices. The use of n- and p-type GaAs matrices allows us to study separately electron and hole levels in the quantum dots by the deep-level transient spectroscopy technique. From analysis of deep-level transient spectroscopy measurements it follows that the quantum dots have electron levels 130 meV below the bottom of the GaAs conduction band and heavy-hole levels at 90 meV above the top of the GaAs valence band. Combining with the photoluminescence results, the band structures of InAs and GaAs have been determined. (C) 2000 Elsevier Science B.V. All rights reserved.

Characteristics of circular waveguide photodetectors using SiGe/Si multiple quantum wells

We report on the fabrication of circular waveguide photodetectors with a response near 1.3 mu m wavelength using SiGe/Si multiple quantum wells. The quantum efficiency of the circular waveguide photodetector is improved when compared with that of the rib waveguide photodetector in the same wavelength at 1.3 mu m The frequency response of the photodetectors is simulated. The emciency-bandwidth product of the circular waveguide photodetectors is improved correspondingly. (C) 2000 Published by Elsevier Science B.V. All rights reserved.