SiH4／C2H4体系激光合成SiC超细粉

本文报道了ＳｉＨ４／Ｃ２Ｈ４体系激光合成ＳｉＣ超细粉研究及对合成的ＳｉＣ超细粉进行的ＴＥＭ（ＴＥＤ）、ＸＲＤ、ＦＴＩＲ、ＸＰＳ及Ｒａｍａｎ散射等测试分析。在部分样品中发现了ＳｉＣ空心颗粒，讨论了ＳｉＣ超细粉的成核成长规律，得出了一些有价值的新结果：ＳｉＣ超细粉的合成由Ｓｉ成核生长和碳化组成；反应温度较高时，为获得接近化学计量化的ＳｉＣ超细粉，要求有较高的源气Ｃ／Ｓｉ比，并且高的Ｃ／Ｓｉ比有利于降低     

硅基GaN外延晶体学位相关系和生长机理研究

采用反应蒸发光地在提高缓冲层的生长温度,通过对Ｓｉ基上ＧａＮ样品缓冲层区域的高分辨透射电镜像（ＨＲＴＥＭ）和界面区域的选区电子衍射（ＳＡＥＤ）分析的基础上,提出了本系统ＧａＮ外延的晶体学位相关系和生长机理。ＧａＮ与Ｓｉ衬底之间存在着下列的晶体学位相关系：ＧａＮ〈０００１〉∥Ｓｉ〈１１１〉,ＧａＮ〈１１２０〉∥Ｓｉ〈１１０〉,ＧａＮ外延生长首先在硅衬底上形成ＧａＮ晶核,生长出ＧａＮ多晶缓冲层,ＧａＮ     

含活性基团硅氮烷先驱体的裂解

用ＴＧ－ＧＣ，ＩＲ，元素分析，ＸＲＤ研究ＭｅＳｉＨＣｌ２与ＭｅＳｉＶｉ（Ｖｉ：－ＣＨ＝ＣＨ２）Ｃｌ２共氨解产物的裂解过程。     

硅基GaN外延层的SIMS及XPS研究

采用真空反应法在硅基上制备出ＧａＮ外延层。利用二次离子质谱和Ｘ射线光电子能谱对ＧａＮ外延层进行了深度剖析和表面分析,结果表明,外延层中Ｇａ和Ｎ分布均匀;在表面处Ｇａ发生了偏聚,外延层中还存在Ｓｉ,Ｏ等杂质,但这些并未影响到ＧａＮ外延层的物相及发生性能,实验还表明,在外延生长前采用原位清洗可去除Ｓｉ衬底表面的氧。     

GaN的MOVPE生长和m－i－n型蓝光LED的试制

利用自行研制的常压ＭＯＶＰＥ设备和全部国产ＭＯ源，采用低温生长缓冲层技术，在蓝宝石（α－Ａｌ２Ｏ３）衬底上获得了高质量的ＧａＮ外延层。未掺杂的ＧａＮ外延层的室温电子迁移率已达１１４ｃｍ２／Ｖ．ｓ，载流于浓度为２×１０１８。７７Ｋ光致发光谱近带边发射峰波长为３６５ｎｍ，其线宽为４ＤｍｅＶ。Ｘ射线双晶衍射回摆曲线的线宽为３６０ａｒｃｓｅｃ。用Ｚｎ掺杂生长了绝缘的ｉ－ＧａＮ层。在此基础上研制了ｍ－ｉ－ｎ型ＧａＮ的ＬＥＤ，并在室温正向偏压下发出波长为４５５ｎｍ的蓝光。     

InGaN/AlGaN双异质结蓝光和绿光发光二极管

报道了用ＬＰ－ＭＯＶＰＥ技术在蓝宝石衬底上生长出以双掺Ｚｎ和Ｓｉ的ＩｎＧａＮ为有源区的蓝光和绿光ＩｎＧａＮ／ＡｌＧａＮ双异质结结构,并研制成功发射波长分别为４３０－４５０ｎｍ和５２０－５４０ｎｍ的蓝光和绿光ＬＥＤ。据查,这是国内首次有关六方ＧａＮ基绿光ＬＥＤ的报道。     

光导型GaN/Si探测器的研制

采用ＭＯＣＶＤ技术在Ｓｉ（１１１）衬底上生长ＧａＮ薄膜,经此材料制备成光导型Ｓｉ基ＧａＮ紫外探测器。探测器的光谱响应表明,在紫外波段２５０￣３６０ｎｍ有近于平坦的光电流响应,３６３ｎｍ附近有陡峭的截止边,３５７ｎｍ波长处５Ｖ偏压下的响应度高达６．９Ａ／Ｗ。响应度与偏压的变化关系表明,４Ｖ以前为线性增加,５Ｖ后达到饱和。     

分子束外延生长GaAs中δ掺杂研究

利用二次离子质谱（ＳＩＭＳ）和电化学剖面Ｃ－Ｖ方法研究了生长温度对ＧａＡｓ中理想Ｓｉδ掺杂的结构的偏离和掺杂原子电微活效率的影响。实验发现，外延生长Ｓｉδ掺杂，ＧａＡｓ时，随着生长温度的升高，Ｓｉ掺杂分布ＳＩＭＳ峰非对称展宽。表面分凝作用加强，但不影响Ｓｉ原子扩散。另外，Ｓｉ施主电激活效率随着生长温度的提高而增大。     

蓝色发光材料MGa2S4:Ce(M=Ca,Sr)发光特性的研究

制备了可用于蓝色ＴＦＥＬ的粉末发光材料ＭＧａ２Ｓ４：Ｇｅ（Ｍ＝Ｃａ，Ｓｒ）地其昌体结构进行了Ｘ射线分析，测量并其激光光谱和发射光谱，研究了Ｃｅ＾３＋浓度的变化对ＣａＧａ２Ｓ４：Ｃｅ和ＳｒＧａ２Ｓ４：Ｃｅ的激光光谱，发射光谱、色纯工及发光强度的影响，同时研究了基质组分的改变对发光特性的影响，结果表明，ＣａＧａ２Ｓ４：Ｃｅ和ＳｒＧａ２Ｓ４：Ｃｅ的可发射纯蓝色光，色纯度好，对ＣａＧａ２Ｓ４：Ｃｅ来说，实     

SiNx钝化膜厚度对pHEMT的性能影响

深入地研究了ＳｉＮｘ钝化膜厚度对ＡｌＧａＡｓ／ＩｎＧａＡｓ／ＧａＡｓ ｐＨＥＭＴ电性能的影响,实验结果表明,ｐＨＥＭＴ器件的截止频率随着氮化硅钝化膜厚度的增加而下降;妆膜厚超过２００ｎｍ时,将影响ｐＨＥＭＴ器件电特性。     

Effects of SiC buffer layer growth temperature on the residual strain of GaN/SiC/Si thin films

Effects of SiC buffer layers were studied on the residual strain of GaN films grown on 3C-SiC/Si (111) substrates. It was clearly observed by Raman scattering measurement that the residual strain of the GaN/Si is reduced by inserting the SiC intermediate layer. Furthermore, residual strain within the GaN/SiC/Si films decreased when the growth temperature of the SiC buffer layer decreased. It was proposed that the irreversible creep phenomenon occurs during the high temperature growth of SiC, affecting nature of the residual strain within the SiC and the GaN layers.     

氮化时间对扩镓硅基GaN晶体膜质量的影响

采用射频磁控溅射在扩镓硅基上溅射Ga2O3薄膜,然后氮化反应组装GaN晶体膜,并研究氮化时间对薄膜晶体质量的影响。测试结果表明：采用两步法生长得到六方纤锌矿结构的GaN多晶膜,扩镓硅层有效的抑制了硅衬底的氮化和弛豫了GaN与Si衬底的热失配。同时显示：在相同的氮化温度下,晶粒尺寸随氮化时间的增加而增大,薄膜的晶化程度相应的得到提高。     

Growth process from amorphous GaN to polycrystalline GaN on Si (111) substrates

Amorphous GaN (a-GaN) films on Si (111) substrates have been deposited by RF magnetron sputtering with GaN powder target. The growth process from amorphous GaN to polycrystalline GaN is studied by XRD, SEM, PL and Raman. XRD data mean that annealing under flowing ammonia at 850-950 °C for 10 min converts a-GaN into polycrystalline GaN (p-GaN). The growth mechanism can be mostly reaction process through N³⁻ in amorphous GaN replaced by N³⁻ of NH₃. Annealing at 1000 °C, the appearance of GaN nanowires can be understood based on the vapor-liquid-solid (VLS) mechanism. In addition, XRD, PL and Raman measurement results indicate that the quality of GaN films increases with increasing temperature. The tensile stress in the films obtained at 1000 °C is attributable to the expansion mismatch between GaN and Si, with the gallium in the film playing a negligible role.     

Deposition of GaN films on (1 1 1) Si substrates by alternate supply of TMG and NH3

GaN films were grown on (1 1 1) Si substrates at 1000 °C by separate admittances of trimethylgallium (TMG) and ammonia (NH₃). To achieve high quality GaN films, the optimization in growth temperature and layer thickness of AlN buffer layer between GaN film and Si substrate is required. Cross-sectional transmission electron microscopic observations of the GaN/(1 1 1)Si samples show a nearly parallel orientation relationship between the (0 0 0 1) planes of GaN film and the (1 1 1) planes of Si substrate. Room temperature photoluminescence spectra of high quality GaN films show a strong near band edge emission and a weak yellow luminescence. The achievement of high quality GaN films on (1 1 1) Si substrates is believed to be attributed to enhancement in surface mobilities of the adsorbed surface species and adequate accommodation of lattice mismatch between high temperature AlN buffer layer and Si substrate.     

Growth of GaN films with controlled out-of-plane texture on Si wafers

GaN films were deposited on Si (400) wafers by a pulsed laser deposition technique, and it was shown that out-of-plane texture of the film is controllable although the film and the substrate do not have any interface epitaxy. The texture of the film can be set either in c-axis or a-axis direction, thereby achieving polar or nonpolar film surfaces as desired. The GaN film and Si substrate were found to be separated by a thin amorphous interface layer consisting of Si, Ga, and O atoms, that can enhance the bonding between GaN and Si. This study shows the possibility of depositing GaN films on Si wafers at low cost and the potential of integrating Si based electronics with GaN based optoelectronics.     

等离子体辅助有机金属(CH_3)_3Ga化学气相沉积GaN薄膜

采用ECR等离子体辅助技术,融合化学气相沉积法,在450℃的相对低温条下于Si(100)衬底上生长出GaN薄膜.对样品进行了XRD、FT-IR和AFM表征,并在制备过程中采集到反应室中N_2-(CH_3)_3Ga等离子体的发射光谱.结果表明,所制备的多晶体GaN薄膜是由N_2-(CH_3)_3Ga等离子体中的活性成分通过复杂的反应生成的,其生长过程符合岛状生长机制.     

The growth of GaN films by alternate source gas supply hot-mesh CVD method

Gallium nitride (GaN) films and Aluminium nitride (AlN) layers were deposited on SiC/Si (111) substrates by an alternating source gas supply or an intermittent supply of a source gas such as ammonia (NH₃), trimethylgallium (TMG) or trimethylaluminum (TMA) in a hot-mesh chemical vapor deposition (CVD) apparatus. The AlN layer was deposited as a buffer layer using NH₃ and TMA on a SiC layer grown by carbonization on Si substrates using propane (C₃H₈). GaN films were grown on an AlN layer by a reaction between NH_x radicals generated on a ruthenium (Ru) coated tungsten (W)-mesh and TMG molecules. An alternating source gas supply or an intermittent supply of one of the source gases during the film growth are expected to be effective for the suppression of gas phase reactions and for the enhancement of precursor migration on the substrate surface. By the intermittent supply of alkylmetal gas only during the growth of the AlN layer, the defect generation in the GaN films was reduced. GaN film growth by intermittent supply on an AlN buffer layer, however, did not lead to the improvement of the film quality.     

Characterization and properties of GaN films deposited by middle-frequency magnetron sputtering with anode-layer ion source assistance

GaN films were deposited on Si (111) substrates at a high growth rate of 94 nm/min using middle-frequency (MF) magnetron sputtering method with anode-layer ion source assistance. XRD, TEM and PL experiments were used to investigate the structure and optical properties of the resulting films. GaN films produced under optimal conditions have an almost 1:1 N: Ga ratio. The O concentration decreased while the deposition rate increased with the increasing of bias voltages. Hexagonal polycrystal nature of the films was detected by the TEM and XRD measurements. Peaks located at 3.36 eV labeled as free-exciton were detected in the temperature dependence photoluminescence spectra. The binding energies of N 1s and Ga 3d were centered at 397.5 and 19.8 eV, respectively. The results show that the ion beam-assisted MF reactive magnetron sputtering method can be an encouraging method for deposition of polycrystalline GaN films at low temperatures.     

ZnO薄膜的晶体性能的分析

在硅基上制备出了c轴取向高度一致的ZnO薄膜 ,这将有可能成为新型GaN单晶薄膜的过渡层。对ZnO薄膜的晶体性能进行了分析 ,研究不同衬底和不同衬底温度对ZnO薄膜的结晶状况的影响 ,并着重用TEM研究了硅基ZnO薄膜的晶体性能。     

Characterization and properties of GaN films deposited by middle-frequency magnetron sputtering with anode-layer ion source assistance

GaN films were deposited on Si (111) substrates at a high growth rate of 94 nm/min using middle-frequency (MF) magnetron sputtering method with anode-layer ion source assistance. XRD, TEM and PL experiments were used to investigate the structure and optical properties of the resulting films. GaN films produced under optimal conditions have an almost 1:1 N: Ga ratio. The O concentration decreased while the deposition rate increased with the increasing of bias voltages. Hexagonal polycrystal nature of the films was detected by the TEM and XRD measurements. Peaks located at 3.36 eV labeled as free-exciton were detected in the temperature dependence photoluminescence spectra. The binding energies of N 1s and Ga 3d were centered at 397.5 and 19.8 eV, respectively. The results show that the ion beam-assisted MF reactive magnetron sputtering method can be an encouraging method for deposition of polycrystalline GaN films at low temperatures.