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1.
研究了金属有机物化学气相外延(MOVPE)方法生长的非故意掺杂的立方相GaN的持续光电导效应.在六方相GaN中普遍认为持续光电导效应与黄光发射有关,而实验则显示在立方GaN中,持续光电导效应与其中的六方相GaN夹杂有关系,而与黄光发射没有关系.文中提出,立方相GaN与其中的六方相GaN夹杂之间的势垒引起的空间载流子分离是导致持续光电导现象的物理原因.通过建立势垒限制复合模型,解释了立方相GaN的持续光电导现象的物理过程,并对光电导衰减过程的动力学作了分析.对实验数据拟合的结果证明以上的模型和推导是与实验相符的. 相似文献
2.
立方GaAs(100)衬底上制备单相六方GaN薄膜 总被引:2,自引:0,他引:2
立方 Ga As (10 0 )衬底上制备的 Ga N薄膜多为立方结构且立方相为亚稳相 ,采用水平常压 MOCVD方法在立方 Ga As (10 0 )衬底上制备出了 Ga N薄膜 . XRD测试表明 ,薄膜具有单一的相 .结合对工艺条件的分析 ,认为薄膜具有六方结构 .最后 ,通过 Raman光谱测试 ,证实在立方 Ga As衬底上制备出了单相六方 Ga N薄膜 .还对立方 Ga As衬底上制备出六方 Ga N薄膜的原因进行了讨论 相似文献
3.
在蓝宝石(0001)衬底上采用金属有机物化学气相淀积(MOCVD)方法生长了未掺杂的Al0.15Ga0.85N外延层,并以此为材料制作了光电导探测器,实验发现探测器具有显著的紫外光响应.分析了探测器持续光电导效应(PPC)的产生机理. 相似文献
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5.
高质量立方相InGaN的生长 总被引:3,自引:3,他引:0
利用 LP- MOCVD技术在 Ga As( 0 0 1 )衬底上生长了高质量的立方相 In Ga N外延层 .研究了生长速率对 In Ga N质量的影响 ,提出一个简单模型解释了在改变 TEGa流量条件下出现的In组分的变化规律 ,实验结果与模型的一次项拟合结果较为吻合 ,由此推断 ,在现在的生长条件下 ,表面单个 Ga原子作为临界晶核吸附 Ga或 In原子实现生长的模型与实际情况较为接近 .对于晶体质量的变化也给予了说明 .得到的高质量立方相 In Ga N室温下有很强的发光峰 ,光致发光峰半高宽为 1 2 8me V左右 . 相似文献
6.
AlGaN紫外光电导探测器的研究 总被引:1,自引:0,他引:1
在蓝宝石(0001)村底上采用金属有机物化学气相淀积(MOCVD)方法生长了未掺杂的Al0.15Ga0.85N外延层,并以此为材料制作了光电导探洲器,实验发现探测器具有显著的紫外光响应。分析了探测器持续光电导效应(PPC)的产生机理。 相似文献
7.
高倍增GaAs光电导开关的光激发电荷畴模型 总被引:10,自引:7,他引:3
结合实验中观察到的光激发电荷畴现象 ,提出光激发电荷畴理论模型描述高倍增 Ga As光电导开关的瞬态特性 ,讨论了高倍增 Ga As光电导开关的非线性特性如上升时间、时间延迟和光能、电场阈值 ,光激发电荷畴的成核、生长以及畴内发生的碰撞电离和辐射复合决定了高倍增 Ga As光电导开关的引发和维持相 ,理论计算结果与实验测试相符合 相似文献
8.
基于热力学平衡理论,对在电子回旋共振等离子体增强金属有机化学气相沉积系统中的Ga N薄膜生长给出了一个化学平衡模型.计算表明,Ga N生长的驱动力Δp是以下生长条件的函数: 族输入分压,输入 / 比,生长温度.计算了六方和立方Ga N的生长相图,计算结果和我们的实验结果显示出一定的一致性.通过分析,解释了高温和高 / 比生长条件适合六方Ga N的原因.上述模型可以延伸到用于Ga N单晶薄膜生长的类似系统中. 相似文献
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10.
N型GaN的持续光电导 总被引:5,自引:2,他引:3
本文报道了金属有机物化学气相外延(MOVPE)生长的未人为掺杂和掺Sin-GaN的持续光电导(PersistentPhotoconductivity——PPC).在不同温度下观察了光电导的产生和衰变行为.实验结果表明,未人为掺杂和掺Sin-GaN的持续光电导和黄光发射可能起源于深能级缺陷,这些缺陷可以是VGa空位、NGa反位或者VGa-SiGa络合物.和未人为掺杂样品A相比,样品B中因Si的并入导致GaN中的深能级缺陷增加,提高了GaN中黄光发射,使持续光电导衰变减慢,但实验未发现黄光的加强和光电导衰变特 相似文献
11.
D. Zhi U. Tisch S. H. Zamir M. Wei E. Zolotoyabko J. Salzman 《Journal of Electronic Materials》2000,29(4):457-462
Thin GaN films, grown by metal organic chemical vapor deposition on the basal plane of sapphire substrates, were characterized
by x-ray pole figures, high-resolution x-ray diffraction and transmission electron microscopy. This combination was found
sensitive to small amounts (down to 0.1%) of cubic GaN phase in specimens subjected to surface nitridation treatment prior
to epitaxial growth. The presence of the cubic phase and its orientation relations to the hexagonal GaN matrix was established
by means of pole figures and selected area electron diffraction. The amount of cubic phase was determined by comparing the
integrated x-ray diffraction intensities of the (311) cubic GaN and the (11.2) hexagonal GaN reflections. Optimum nitridation
duration was found, which corresponds to almost complete suppression of the cubic phase formation. 相似文献
12.
C. H. Wei Z. Y. Xie L. Y. Li Q. M. Yu J. H. Edgar 《Journal of Electronic Materials》2000,29(3):317-321
The growth of cubic GaN on 3C-SiC/Si(100) by metal-organic chemical vapor deposition (MOCVD) under various growth temperatures,
thicknesses of 3C-SiC, and V/III ratios was studied. The fractions of cubic and hexagonal phases in the films were estimated
from the integrated x-ray diffraction intensities of the cubic (002) and hexagonal (1011) planes. A smooth SiC layer, a high
growth temperature, and a moderate V/III ratio are three key factors for the nucleation of the cubic phase and its subsequent
growth. Hexagonal GaN with its c-axis perpendicular to the substrate preferentially grows at the low temperature of 750°C.
The inclusion of the cubic phase increases with increasing growth temperature. The optimum growth conditions for dominant
cubic GaN formation were a growth temperature of 950°C, a 1.5 μm thick SiC layer, and a V/III ratio of 1500. With these growth
conditions, a cubic GaN layer with the cubic component of 91% was obtained. 相似文献
13.
GaN外延材料中持续光电导的光淬灭 总被引:1,自引:1,他引:0
研究了非故意掺杂和掺Si的n型GaN外延材料持续光电导的光淬灭。实验发现非故意掺杂GaN的持续光电导淬灭程度远大于掺Si的n型GaN;撤去淬灭光后前者的持续光电导几乎没有变化,后者的却有明显减小;稍后再次加淬灭光前者的持续光电导无变化,而后者的有明显增加。我们认为两者持续光电导的形成都与空穴陷阱有关,用空穴陷阱模型解释了非故意掺杂GaN持续光电导的形成以及淬灭;认为掺Si的n型GaN的持续光电导是电子陷阱(杂质能级)和空穴陷阱共同作用的结果,并且在持续光电导发生的不同阶段其中一种陷阱的作用占主要地位。 相似文献
14.
对光致发光谱中无黄光和有强黄光的两组GaN样品作了Si离子注入 ,研究了Si离子注入及退火温度对其黄光的影响 .当退火温度升高时 ,不管是哪一组样品 ,其黄光强度和黄光强度与带边发光带强度之比都是增强的 .无黄光的GaN样品在注入Si离子并经退火后出现明显的黄光 ;而有强黄光的GaN样品经相同处理后 ,其黄光强度较原生样品大大降低 .实验结果表明离子注入加上适当退火会在GaN中引入与黄光有关的深受主缺陷从而使黄光强度增加 ,此外 ,在离子注入过程中GaN表面不仅可以吸附离子注入引入的点缺陷 ,而且还能够吸附GaN中原有的与黄光有关的点缺陷 ,这种吸附作用随离子注入剂量增加而变强 . 相似文献
15.
基于热力学平衡理论,对在电子回旋共振等离子体增强金属有机化学气相沉积系统中的GaN薄膜生长给出了一个化学平衡模型.计算表明,GaN生长的驱动力Δp是以下生长条件的函数:Ⅲ族输入分压,输入Ⅴ/Ⅲ比,生长温度.计算了六方和立方GaN的生长相图,计算结果和我们的实验结果显示出一定的一致性.通过分析,解释了高温和高Ⅴ/Ⅲ比生长条件适合六方GaN的原因.上述模型可以延伸到用于GaN单晶薄膜生长的类似系统中. 相似文献
16.
Effect of In Situ Thermal Cycle Annealing on GaN Film Properties Grown on (001) and (111) GaAs, and Sapphire Substrates 总被引:1,自引:0,他引:1
The effect of in-situ thermal cycle annealing (TCA) has been investigated for GaN growth on GaAs(lOO), GaAs(111) and sapphire
substrates. X-ray diffractometry (XRD) and surface morphology studies were performed for this purpose. Enhanced cubic phase
characteristics were observed by employing annealingfor GaN layers grown on (001) GaAs. The thickness of the layer subject
to annealing is critical in determining the phase of the subsequently grown layer. Thin initial layers appear to permit maintenance
of the cubic phase characteristics shown by the substrate, while hexagonal phase characteristics are manifested for thick
initial layers. Higher temperature of annealing of thick pre-annealed layers results in changes from mixed cubic/hexagonal
phase to pure hexagonal phase. Growth on GaAs(111) substrates showed single cubic phase characteristics and similar enhancement
of crystal quality by using TCA as for layers on GaAs(OOl). Micro-cracks were found to be present after TCA on GaAs(lll) substrates.
Thermal cycling also appears to be beneficial for layers grown on sapphire substrates. 相似文献
17.
A. V. Andrianov K. Yamada H. Tampo H. Asahi V. Yu. Nekrasov Z. N. Petrovskaya O. M. Sreseli N. N. Zinov’ev 《Semiconductors》2002,36(8):878-882
The low-temperature time-resolved photoluminescence of polycrystalline GaN layers grown by molecular beam epitaxy on metal substrates (Mo and Ta) was investigated. The photoluminescence spectra observed include two emission bands in the ultraviolet spectral region. We assign one of these bands to recombination processes inside cubic nanocrystallites, which are formed in the hexagonal polycrystalline GaN host. The recombination radiation of cubic nanocrystallites is enhanced due to predominant trapping of the nonequilibrium electron-hole pairs in these crystallites. 相似文献
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19.
采用电泳沉积法在Si(111)衬底上制备GaN薄膜,并研究退火温度对GaN薄膜晶体质量、表面形貌和发光特性的影响。傅立叶红外吸收谱(FTIR)、X射线衍射(XRD)和扫描电镜(SEM)的测试结果表明所得样品为六方纤锌矿结构的GaN多晶薄膜,随退火温度的升高,晶粒尺寸增大,结晶化程度提高。室温下光致发光谱的测试发现了位于367 nm处的强发光峰和437 nm处的弱发光峰,其发光强度随退火温度的升高而增强,但发光峰的位置并不发生移动。 相似文献
20.
Sun Jung Kim Young Hun Seo Kee Suk Nahm Yun Bong Hahn Hyun Wook Shim Eun-Kyung Suh Kee Young Lim Hyung Jae Lee 《Journal of Electronic Materials》1999,28(8):970-974
The origin of the radiative recombination leading to yellow luminescence (YL) has been elucidated by the study of luminescence
properties of GaN films grown with two different gas feeding methods. GaN films were grown on a (0001) sapphire substrate
in a rapid thermal chemical vapor deposition (RTCVD) reactor. GaN films emitted two different luminescence energies, 2.2 and
3.47 eV, depending on the introducing position of hydrogen gas in the growth reactor. The distribution of the TMGa flow and
gas phase reactions in the reactor were investigated to understand the effect of the gas feeding methods on the optical properties
of GaN films. The results suggest that YL is related to Ga vacancies in the grown films. 相似文献