The epitaxial growth of devices based on gallium antimonide (GaSb) is negatively impacted by defects related to impurities in the crystal. Liquid encapsulated czochralski (LEC) technology was used to grow 2 -inch Te-doped GaSb (100) single crystal ingots, which were then processed into polished wafers in order to investigate the origins and consequences of defects related to impurities. Polished GaSb wafers were found to have surface micro -defects. Energy dispersive x-ray spectroscopy (EDAX) and scanning electron microscopy (SEM) measurements indicate that the micro -defects are associated with carbon and oxygen impurities. Glow discharge mass spectrometry (GDMS) is used to identify the origins of carbon and oxygen impurities. Based on the findings, an optimization process was developed to enhance the crystal quality, and a micro -defect -free GaSb single crystal was produced.

Subsurface damage of (100)-oriented InAs wafers generated in chemical-mechanical polishing processes has been investigated by wet chemical etching and optical microscopy. The trend of corrosion rate as a function of removal thickness in the process of chemical etching is a powerful statement that subsurface damage exists in the polished InAs substrate. Besides, a new method based on the changes in the morphology of the shallow pits caused by preferential corrosion has been established for InAs (100) surface to reveal the subsurface damage induced during the polishing process. The nature and formation mechanism of shallow pits are discussed in detail.

Nanoscale-depth comet defects have been reported. They are a type of dislocation-driven nanostructure found in a semi-insulating Fe-InP substrate. Nomarski optical microscopy with the function of universal-differential interference contrast reflection (U-DICR), scanning electron microscopy, and atomic force microscopy revealed the presence of comet defect morphology features that contain a head and a tail and was subtle in scanning electron microscopy. We further employed the photoelectric coupling technique to prepare lamellae using a focused ion beam in a scanning electron microscope and demonstrated the growth mechanism through transmission electron microscopy energy-dispersive x-ray spectroscopy. Finally, we proposed an inhibition method for comet defects using two scenarios: controlling the substrate surface chemistry ratio of indium and phosphorus and optimizing of process parameters, such as desorption, prior to epitaxial growth.

For the measurement of responsivity of an infrared photodetector,the most-used radiation source is a blackbody.In such a measurement system,distance between the blackbody,the photodetector and the aperture diameter are two parame-ters that contribute most measurement errors.In this work,we describe the configuration of our responsivity measurement sys-tem in great detail and present a method to calibrate the distance and aperture diameter.The core of this calibration method is to transfer direct measurements of these two parameters into an extraction procedure by fitting the experiment data to the calculated results.The calibration method is proved experimentally with a commercially extended InGaAs detector at a wide range of blackbody temperature,aperture diameter and distance.Then proof procedures are further extended into a detector fabricated in our laboratory and consistent results were obtained.

Oxidation layer and particles on polished and epi-ready cleaned surface of GaSb (1 0 0) wafers have been investigated and analyzed by surface scanner KLA candela, scanning electron microscope (SEM), X-ray photoelectron spectroscopy (XPS) and photoluminescence (PL) measurements, respectively. From a large quantity of statistical results, most of the particles are related with the oxides of gallium and antimony. GaSb wafers from upper position of a single crystal ingot exhibits a high surface reactivity with the characteristics of being oxidized easily and more particles left on the surface. After the standard wafer clean process, more particles are detected on the wafer surface from this ingot region, implying a correlation between native gallium antisite acceptor concentration (electrical compensation) and particle adhesion by a combination of SEM, XPS and PL results. The key role of the oxide layer composition, Ga-rich property and the defect states in producing oxidation and particle adhesion behavior has been discussed.

采用液封直拉(LEC)法批量生长的直径2英寸(1英寸=2.54 cm)n型Te-GaSb(100)单晶的位错腐蚀坑密度(EPD)通常低于300 cm-2,达到无位错水平.本文利用X射线摇摆曲线以及倒易空间图(RSM)对这种GaSb单晶抛光衬底的晶格完整性和亚表面损伤情况进行了分析表征,结果表明经过工艺条件优化的化学机械抛光处理,GaSb单晶衬底表面达到原子级光滑,不存在亚表面损伤层.利用分子束外延在这种衬底上可稳定生长出高质量的Ⅱ类超晶格外延材料并呈现出优异的红外探测性能.在此基础上,对CaSb衬底材料的物性、生长制备和衬底加工条件之间的内在关系进行了综合分析.

Raman spectroscopy has been used to characterize and compare residual stress distribution across wafers sliced from un-doped InP and InAs single crystals grown by liquid encapsulated Czochralski (LEC) and vertical tem-perature gradient freezing (VGF) methods, respectively. Both VGF-InP and VGF-InAs wafers exhibit greater residual stress but even distribution across the wafer than their LEC wafers. There is an inverse distribution correlation between the residual stress and the Full width at half maximum (FWHM) of Raman peak for the wafer grown by LEC or VGF method. The flatness results suggest that VGF-grown wafers generally have better flatness parameters but with higher residual stress than LEC-grown wafers.

Raman spectroscopy has been used to evaluate residual stress distribution across GaSb single crystal wafers with different Te doping concentrations grown by liquid encapsulated Czochralski (LEC) method. Undoped GaSb wafers grown by LEC and vertical temperature gradient freezing method were used as reference wafers for comparison analysis. The residual stress increases but its distribution uniformity improves in LEC-GaSb wafers with the concentration of Te dopant increasing. Moreover, annealing at temperature 650 °C can effectively increase its distribution uniformity and results in an improvement of the flatness. The results also suggest that the flatness of GaSb wafers is better when Te doping concentration is controlled within a certain range.

立方砷化硼(BAs)为间接带隙、闪锌矿结构的Ⅲ-Ⅴ族化合物半导体材料.理论分析预测BAs具有仅次于金刚石的超高热导率,在电子器件散热领域表现出广阔应用前景,成为当前的研究热点.近年来立方BAs单晶材料的制备取得突破性进展,采用化学气相传输法(CVT)合成了毫米尺寸的高质量单晶,室温下热导率高达1300 W·m-1·K-1.本文介绍了BAs单晶的性质和生长方法,综述了材料研究进展,阐述了晶体生长面临的技术挑战,并对发展前景进行了展望.

Etch pits formed on (100)-oriented InAs surface by HCl-H2SO4-H2O solutions have been investigated by optical microscopy and atomic force microscopy (AFM) images. Depending on the composition of etchant, four types of etch pits are observed, which is attributed to different reaction rate of (1 1 1)A and (1 1 1)B planes by HCl and H2SO4. Excessive HCl results in long hexagonal shaped pits, whereas the addition of H2SO4 results in tetragonal pits. The direction of the composed pit sidewalls has been determined combining with the results of depth profiles on (110) and (1 (1) over bar0) planes. The role of the HCl and H2SO4 in the over-all etching behavior of InAs and details about the geometrical relation between the sidewalls of the etch pits are discussed.

InAs single crystals grown by the liquid-encapsulated Czochralski (LEC) method and vertical gradient freezing (VGF) are studied by low-temperature photoluminescence spectroscopy, infrared transmission and reflectance spectroscopy, double-crystal x-ray diffraction and Hall effect measurement, respectively. A properly controlled etching solution is used to reveal beautiful square dislocation etch pits in the crystals. In addition to extremely low dislocation density, the concentration of native defects in the VGF-InAs single crystals is much lower than that in LEC-InAs, giving VGF-InAs better electrical and optical properties. The nature of the defects in InAs single crystals is discussed by considering the variation in stoichiometry and environment during the crystal growth processes.

Dislocation etch pits with clear rectangular and elongated hexagonal shapes on indium arsenide (1 0 0) wafer surface have been obtained by carefully controlling the etch condition of HCl-based etchant with the addition of a surfactant. Etching activation energies of (1 0 0), (1 1 1) A and (1 1 1) B faces have been obtained by etching at different temperatures. The results suggest a chemically-controlled reaction restricted by the surfactant. Indices of the facet surfaces in the pits were analyzed with the aid of optical microscopy as well as pit side wall cross section observation by cleavage. It is similar to the etch pit facets of an In-doped GaAs wafer. Mechanism of the etching behavior of InAs has been discussed based on the results.

Te-doped GaSb single crystal grown by the liquid encapsulated Czochralski (LEC) method exhibits a lag of compensating progress and a maximum carrier concentration around 8×1017 cm−3. The reason for this phenomenon has been investigated by a quantity concentration evaluation of the Te donor and native acceptor. The results of glow discharge mass spectrometry (GDMS) and Hall measurement suggest that the acceptor concentration increases with the increase of Te doping concentration, resulting in the enhancement of electrical compensation and free electron concentration reduction. The acceptor concentration variation is further demonstrated by photoluminescence spectra and explained by the principle of Fermi level dependent defect formation energy.

Carbon-ion-implanted InAs was investigated using double-crystal x-ray diffraction (DCXRD), Hall measurement and infrared absorption (IR) analysis. Multiple implantation were made at 0.1–0.4 MeV with 6.0 × 1012–2.0 × 1013 ions cm−2. After rapid thermal annealing at 300 °C for 20 s, the implantation-induced damage was removed substantially, indicating the recovery of crystallinity. The results of Hall measurement reveal strong electrical compensation and low conductivity in the implanted layer of the sample, suggesting the formation of acceptor CAs. In contrast, the lowest IR transmittance is observed in the 300 °C annealed sample, implying the existence of acceptor with significant concentration. The implanted layer turned to n-type after annealing at 400 °C with the increasing transmittance. After annealing at temperature of 500 °C, the decreasing carrier concentration and the increasing transmittance is attributed to the competition between the decomposition of C–H complexes and the formation of donor centers C–C.

Lightly Te-doped GaSb samples grown by the liquid encapsulated Czochralski (LEC) method have been studied by Hall measurements and low-temperature PL spectroscopy. The results suggest that acceptor-related antisite is the dominant defect in n-type GaSb with low Te-doping concentration. As the Te concentration increases, gallium vacancy related defects become the main acceptor. A new band of around 665 meV is observed in the GaSb sample with the lowest Te-doping concentration. The variation of the acceptor defects and their influence on the electronic and optical property on the n-GaSb single crystal are discussed based on the results.

N-type InAs single crystals have been studied by local vibrational mode (LVM) spectroscopy, photoluminescence spectroscopy (PL), glow discharge mass spectrometry (GDMS) and Hall effect measurement, respectively. Carbon–hydrogen complex defects CH3 and CH2 are detected in as-grown and annealed samples. After annealing, CH3 dissociates and more CH2 is formed. Results of PL and Hall measurement suggest that the complex defects of CH3 act as acceptors in n-type InAs and correlate with the change of electrical compensation after annealing. The 383 meV PL peak is attributed to CH3 defects. Based on the expected energy level of CH3 in InAs, we predicted that CH3 complex defects in InAs should introduce a resonant level 32 meV above the valence band minimum.

The electrical transport properties of Mn doped InAs single crystal (InAs:Mn) were determined from temperature-dependent Hall effect measurements over the temperature range of 77-300 K. Both samples were found to be p-type attributed to Mn acceptors randomly substituting for indium lattice sites. The sample with relatively higher doping concentration exhibits characteristics with nearest-neighbor hopping conductance (NNH) in impurity band below 200 K. The ionization energy of the Mn acceptor in InAs is determined to be 27 meV from the analysis of PL spectrum of the lightly doped sample. It is determined from the value of ionization energy that the localized radius a(0) of the manganese acceptor is 17 angstrom.

p型单晶硅太阳电池在EL检测过程中,部分电池片出现黑斑现象.结合X射线能谱分析(EDS),对黑斑片与正常片进行对比分析,发现黑斑片电池与正常电池片大部分表面的成分相同,排除了镀膜及丝网印刷过程中产生黑斑的可能.利用X射线荧光光谱分析(XRF)测试了同一电池片的黑斑区域与正常区域,发现黑斑处Ca含量较大,并出现Sr、Ge和S等杂质元素.将6个档位的电池片制备成2 cm×2 cm的电池样片,利用光生诱导电流测量了每个电池的外量子效率(EQE).在460～1 000 nm波长范围内,同一电池片黑斑处与正常处的EQE相差较大,说明黑斑的出现与原生硅片缺陷无关,应归结于电池片生产过程中引入的杂质缺陷.给出了杂质引入的原因以及解决途径,从而显著减小了黑斑片产生的几率.

Undoped, S-doped and Fe-doped 4 inch diameter (100) InP single crystals with average dislocation etch pit density less than 5000 cm-2 have been grown by using high pressure vertical temperature gradient Freeze (VGF) method.A multiple points X-ray double crystal diffraction measurement across the 4 inch wafer indicates a full width at half maximum (FWHM) around 30 arcsec with uniform distribution of the rocking curves.Due to the low temperature gradient during the VGF growth process, the possibility of twin generation is quite high compared to that of liquid encapsulated growth process (LEC).However, the orientation of the crystal main body is still (100) direction after the twin formation on the VGF-InP crystal ingots.In this case, a large quantity of (100) single crystal wafers with diameter of 2 inch, 3 inch and 4 inch can be sliced from the ingot.Since the effective segregation coefficient is very low for Fe, polycrystal growth caused by composition super cooling of Fe-doped InP VGF is found frequently.The single crystal yield of the Fe-InP VGF growth can be increased significantly by strictly control the Fe doping quantity and the temperature gradient.Electrical property, dislocation density and its distribution, lattice perfection of the VGF-InP single crystals have been investigated.

SiN x /SiO x passivation and double side P-diffusion gettering treatment have been used for the fabrication of c-Si solar cells. The solar cells fabricated have high open circuit voltage and short circuit current after the double P-diffusion treatment. In addition to better surface passivation effect, SiN x /SiO x layer has lower reflectivity in long wavelength range than conventional SiN x film. As a consequence, such solar cells exhibit higher conversion efficiency and better internal quantum efficiency, compared with conventional c-Si solar cells.