Deep level transient spectroscopy studies of Er and Pr implanted GaN films

Deep level transient spectroscopy measurements were used to characterize the electrical properties of metal organic chemical vapor deposition grown undoped, Er-implanted and Pr-implanted GaN films. Only one deep level located at 0.270 eV below the conduction band was found in the as-grown GaN films. But four defect levels located at 0.300 eV, 0.188 eV, 0.600 eV and 0.410 eV below the conduction band were found in the Er-implanted GaN films after annealing at 900 degrees C for 30 min, and four defect levels located at 0.280 eV, 0.190 eV, 0.610 eV and 0.390 eV below the conduction band were found in the Pr-implanted GaN films after annealing at 1050 degrees C for 30min. The origins of the deep defect levels are discussed. After annealing at 900 degrees C for 30min in a nitrogen flow, Er-related 1538nm luminescence peaks could be observed for the Er-implanted GaN sample. The energy-transfer and luminescence mechanism of the Er-implanted GaN film are described.

The effects of pre-irradiation on the formation of Si1-xCx alloys

Carbon ions were implanted into crystal Si to a concentration of (0.6-1.5)at% at room temperature. Some samples were pre-irradiated with S-29(i)+ ions, while others were not pre-irradiated. Then the two kinds of samples were implanted with C-12(+) ions simultaneously, and Si1-xCx alloys were grown by solid phase epitaxy with high-temperature annealing. The effects of preirradiation on the formation of Si1-xCx alloys were studied. If the dose of implanted C ion was less than that for amorphizing Si crystals, the implanted C atoms would like to combine with defects produced during implantation, and then it was difficult for Si1-xCx alloys to form after annealine, at 950 degreesC. Pre-irradiation was advantageous for Si1-xCx alloy formation. With the increase of C ion dose, the damage produced by C ions increased. Pre-irradiation was unfavorable for Si1-xCx, alloy formation. If the implanted C concentration was higher than that for solid phase epitaxy solution, only part of the implanted C atoms form Si1-xCx alloys and the effects of pre-irradiation could be neglected. As the annealing temperature was increased to 1050 degreesC, Si1-xCx alloys in both pre-irradiated and unpreirradiated samples of low C concentration remained, whereas most part of Si1-xCx alloys in samples with high C concentration vanished.

The growth of SiC on Si substrates with C2H4 and Si2H6

SiC was grown on Si (100) substrates oriented and off-oriented by 2-5 degrees towards [011] with simultaneous supply of C2H4 and S2H6 at 1050 degrees C. SiC formed during removal of oxide could be removed at 1150 degrees C. Twinned growth occurred on both oriented and off-oriented substrates during carbonization, but fewer twins formed on the off-oriented substrate than that on the oriented substrate. In SiC growth process, twinned growth continued on the off-oriented substrate whereas twinned growth stopped and single crystal SiC with double-domain (2 x 1) superstructure formed on the oriented substrate. SiC single crystal could grow on a carbonized twinned buffer layer. Obvious SiC LO and TO phonon modes were observed with Raman spectroscopy in the epilayer grown on the oriented substrate. The surface of the epilayer grown on the oriented substrate was smooth, while there was a high density of islands on the epilayer grown on the off-oriented substrate. The film grown on the oriented substrate is superior than that grown on the off-oriented substrate. (C) 1999 Elsevier Science B.V. All rights reserved.

The effects of carbonized buffer layer on the growth of SiC on Si

Carbonized buffer layers were formed with C2H4 on Si(100) and Si(111) substrates using different methods and SIC epilayers were grown on each buffer layer at 1050 degrees C with simultaneous supply of C2H4 and Si2H6. The structure of carbonized and epitaxy layers was analyzed with in situ RHEED. The buffer layers formed at 800 degrees C were polycrystalline on both Si(100) and Si(111) substrates whereas they were single crystals, with twins on Si(100) and without tu ins on Si(111)substrates. when formed with a gradual rise in substrate temperature from 300 degrees C to growth temperature. Raising the substrate temperature slowly results in the formation of more twins. Epilayers grown on carbonized polycrystalline lavers are polycrystalline. Single crystal epilayers without twins grow on single crystalline buffer layers without twins or with a few twins. (C) 1999 Elsevier Science B.V. All rights reserved.

Boron diffusion in Ge+ premorphized and BF2+ implanted Si(001)

The annealing behavior of Si implanted with Ge and then BF2 has been characterized by double crystal X-ray diffraction (DCXRD) and secondary ion mass spectroscopy (SIMS). The results show that annealing at 600 degrees C for 60 minutes can only remove a little damage induced by implantation and nearly no redistribution of Ge and B atoms has occurred during the annealing. The initial crystallinity of Si is fully recovered after annealing at 950 degrees C for 60 minutes and accompanied by Ge diffusion. Very shallow boron junction depth has been formed. When annealing temperature rises to 1050 degrees C, B diffusion enhances, which leads to a deep diffusion and good distribution of B atoms into the Si substrate. The X-ray diffraction (004) rocking curves from the samples annealed at 1050 degrees C for 60 minutes display two SiGe peaks, which may be related to the B concentration profiles.

INTERACTION OF CO WITH SI AND SIO2 DURING RAPID THERMAL ANNEALING

The interaction of Co with Si and SiO2 during rapid thermal annealing has been investigated. Phase sequence, layer morphology, and reaction kinetics were studied by sheet resistance, x-ray diffraction, Auger electron spectroscopy, x-ray photoelectron spectroscopy, and scanning electron microscopy. With increasing annealing temperature, Co film on Si(100) is transformed sequentially into Co2Si, CoSi, and finally CoSi2 which corresponds to the minimum of sheet resistance. No evidence of silicide formation was observed for Co/SiO2 annealed even at the high temperature of 1050-degrees-C.

基于STM-64的甚短距离并行光传输系统

研究了STM-64数据帧的转换映射技术,利用垂直腔面发射激光器(VCSEL)列阵光源和PIN列阵探测器成功研制出10 Gb/s的甚短距离12信道SDH并行光传输系统,该系统结构紧凑,具有检错和纠错功能。跟传统的10 Gb/s串行光传输系统相比,本系统降低了对单路器件传输性能的要求。经SDH传输测试仪测试,系统能实现无误传输。

掺Er／Pr的GaN薄膜深能级的研究

利用深能级瞬态谱（DLTS）、傅里叶变换红外光谱（FT-IR）对GaN以及GaN掺Er／Pr的样品进行了电学和光学特性分析．研究发现未掺杂的GaN样品只在导带下0．270eV处有一个深能级；GaN注入Er经900℃，30min退火后的样品出现了四个深能级，能级位置位于导带下0．300eV，0．188eV，0．600eV和0．410eV；GaN注入Pr经1050℃，30min退火后的样品同样出现了四个深能级。能级位置位于导带下0．280eV，0．190eV，0．610eV和0．390eV；对每一个深能级的来源进行了讨论．光谱研究表明，掺Er的GaN样品经900℃，30min退火后，可以观察到Er的1538nm处的发光。而且对能量输运和发光过程进行了讨论．

掺镨GaN薄膜的微结构与光致发光

利用背散射／沟道（RBS／C）技术、原子力显微镜（AFM）和光致发光（PL）谱研究了掺镨GaN薄膜的微结构和可见光发光特性。RBS／C结果表明，注入Pr后，在注入层引入了晶格损伤；注入样品经1050℃退火后，部分损伤得到恢复，但是晶体质量没有恢复到注入前的状态。AFM结果表明，注入Pr后，表面凹凸不平，而且在注入区引起了膨胀，膨胀幅度达到23．368nm左右。PL结果表明，在850—1050℃退火，发光强度按e指数增加；当退火温度达到1050℃，发光强度最强，经过数据拟合可得Pr^3＋的热激活能为5．8eV。

GSMBE外延生长SGOI材料的退火行为

在SIMOX SOI超薄硅衬底上外延生长了高质量SiGe合金薄膜来制备SGOI(SiGe on insulator)样品，并研究了其在1050℃氧化气氛中的高温退火行为．用Raman，DCXRD，RBS和光学显微镜等分析手段对SGOI样品在退火前后的性能进行了表征．分析结果表明

预注入对Si_（1-x）C_x合金形成的影响

室温下在单晶Si中注入(0.6-1.5)at%的C原子，部分样品在C离子注入之前在其中注入~(29)Si~+离子产生损伤，然后在相同条件下利用高温退火固相外延了Si_(1-x)C_x合金，研究了预注入对Si_(1-x)C_x合金形成的影响。如果注入C离子的剂量小于引起Si非晶化的剂量，在950℃退火过程中注入产生的损伤缺陷容易与C原子结合形成缺陷团簇，难于形成Si_(1-x)C_x合金，预注入形成的损伤有利于合金的形成。随着C离子剂量的增大，注入产生的损伤增强，预注入反而不利于Si_(1-x)C_x合金的形成，但当注入C原子的浓度超过固相外延的溶解度时，预注入的影响可以忽略。退火温度升高到1050℃，无论预注入还是未预注入样品，C含量低的合金相仍然保留，而C含量高的合金相大部分消失。

Carrier Depth Profile of Si/SiGe/Si n-p-n HBTStructural Materials Characterized by Electrochemical Capacitance- Voltage Method

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