Low-temperature ECR-PEMOCVD deposition of high-quality crystalline gallium nitride films: A comparative study of intermediate layers for growth on amorphous glass substrates

A low temperature growth method based on an electron cyclotron resonance plasma-enhanced metal organic chemical vapor deposition system (ECR-PEMOCVD) was proposed for the growth of GaN (Gallium nitride) films on ordinary amorphous soda-lime glass substrates. To alleviate the large lattice mismatch between GaN film and glass substrate and improve the heat dissipation performance for potential optoelctrical device application, five intermediate layers (Cu, Ni, Ti, Ag, and ITO) were deposited on the glass substrate before the growth of GaN. A comparative study was performed through structural analysis of the as-grown GaN films with various intermediate layers investigated by means of in-situ reflection high energy electron diffraction (RHEED), X-ray diffraction (XRD), and atomic force microscopy (AFM). The results indicate that the Ti intermediate layer has a great advantage over other intermediate layers in view of crystalline quality and smooth surface, therefore is more suitable and preferred for the potential application in optoelectronic devices.     

ECR-PEMOCVD技术生长的GaMnN薄膜的特性

利用电子回旋共振-等离子体增强金属有机物化学气相沉积(ECR-PEMOCVD)技术,在蓝宝石(α-Al2O3)衬底上生长出具有一定Mn含量的GaMnN稀磁半导体薄膜.RHEED图像呈现清晰的斑点状点阵,表明薄膜为单晶,表面不是很平整,为三维岛状生长模式.X射线衍射分析表明薄膜为六方结构,沿c轴方向生长,结晶性良好.AFM显示薄膜是由许多亚微米量级的晶粒按一致的取向规则堆砌而成的.超导量子干涉仪(SQUID)测量显示在室温下薄膜依然具有铁磁性,居里温度约为400K.     

Influence of N2 flux on the improvement of highly c-oriented GaN films on diamond substrates

High-quality GaN films are deposited on freestanding thick diamond films by electron cyclotron resonance plasma-enhanced metal organic chemical vapour deposition (ECR-PEMOCVD). Trimethyl gallium (TMGa) and N₂ are applied as precursors and different N₂ fluxes are used to achieve high-quality GaN films. The influence of N₂ flux on the properties of GaN films is systematically investigated by X-ray diffraction analysis (XRD), reflection high energy electron diffraction (RHEED), atomic force microscopy (AFM) and Hall effect measurement (HL). The results show that the high-quality GaN films with small surface roughness of 4.5 nm and high c-orientation are successfully achieved at the optimized N₂ flux of 90 sccm. The most significant improvements in morphological, structural, and optical properties of GaN films are obtained by using a proper N₂ flux.     

Low-temperature growth of highly c-oriented InN films on glass substrates with ECR-PEMOCVD

High quality InN films are deposited with an interlayer of high c-orientation (002) AZO (Aluminium-doped Zinc Oxide; ZnO:Al) films on glass substrates by electron cyclotron resonance plasma-enhanced metal organic chemical vapor deposition (ECR-PEMOCVD) at low temperature. AZO films used as a buffer layer are effective for the epitaxial growth of InN films. The influence of Trimethyl Indium (TMIn) flux on the properties of InN films is systematically investigated by reflection high energy electron diffraction (RHEED), X-ray diffraction analysis (XRD), atomic force microscopy (AFM) and optical transmittance spectra. The results indicate that high quality InN films with high c-orientation and small surface roughness are successfully achieved at an optimized Trimethyl Indium (TMIn) flux of 5.5 sccm. The InN/AZO structures have great potential for the development of full spectra solar cells.     

衬底氮化时间对玻璃衬底上低温沉积GaN薄膜结晶性的影响

采用电子回旋共振-等离子体增强金属有机物化学气相沉积(ECR-PEMOCVD)方法,在康宁7101型普通玻璃衬底上低温沉积氮化镓(GaN)薄膜.利用反射高能电子衍射(RHEED)、X射线衍射(XRD)、原子力显微镜(AFM)和霍尔测量系统检测样品,研究了衬底氮化时间对GaN薄膜质量的影响.结果表明,氮化时间为5min时,得到的GaN薄膜呈高度c轴择优取向,结晶性较好,薄膜表面是由许多亚微米量级的表面岛按一致的取向规则堆砌而成的,薄膜表面较为平整且呈n型导电;氮化时间增加,薄膜结晶性反而变差.     

在镀铝玻璃衬底上低温沉积GaN薄膜的结晶特性

采用电子回旋共振等离子体增强金属有机物化学气相沉积(ECR-PEMOCVD)方法,在镀铝玻璃衬底上沉积了GaN薄膜.RHEED和XRD分析显示,适当增加TMGa流量,薄膜呈现高度c轴择优取向特征;SEM表明,随着TMGa流量增加,薄膜表面逐渐平整致密;对Raman光谱中A1(TO)、E1(TO)两个禁戒模式及281.1 cm-1附近宽峰出现的原因进行了探讨,并对E2(high)、A1(LO)模的低频移动进行了分析,分析认为E2(high)模低频移动是薄膜内应力和晶粒尺寸效应共同作用的结果,同时晶粒尺寸效应还导致了A1(LO)模的低频移动.     

Deposition and properties of highly <Emphasis Type="Italic">c</Emphasis>-oriented of InN films on sapphire substrates with ECR-plasma-enhanced MOCVD

InN films with highly c-axis preferred orientation were deposited on sapphire substrate by low-temperature electron cyclotron resonance plasma-enhanced metal organic chemical vapor deposition (ECR-PEMOCVD). Trimethyl indium (TMIn) and N2 were applied as precursors of In and N, respectively. The quality of as-grown InN films were systematically investigated as a function of TMIn fluxes by means of reflection high-energy electron diffraction (RHEED), X-ray diffraction analysis (XRD), and atomic force microscopy (AFM). The results show that the dense and uniform InN films with highly c-axis preferred orientation are successfully achieved on sapphire substrates under optimized TMIn flux of 0. 8 ml·min-1. The InN films reported here will provide various opportunities for the development of high efficiency and high-performance semiconductor devices based on InN material.     

采用ECR-PEMOCVD方法进行立方和六方GaN单晶薄膜生长的准热力学模型和相图

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.     

氮气流量对玻璃衬底上低温沉积GaN薄膜结晶性的影响

采用电子回旋共振-等离子体增强金属有机物化学气相沉积（ECR-PEMOCVD）技术,在康宁7101型普通玻璃衬底上沉积了高度c轴择优取向的多晶GaN薄膜. 利用反射高能电子衍射（RHEED) , X射线衍射 (XRD) 对样品进行检测,研究了在低温（430℃）沉积中氮气流量对GaN薄膜结晶性的影响. 并且利用原子力显微镜 (AFM) 和室温光致发光 (PL) 谱研究了薄膜的表面形貌和发光特性,发现薄膜表面形貌较为平整,其发光峰由较强的紫外近带边发光峰和极其微弱的绿光发光峰组成.     

氮化工艺对GaN缓冲层生长的影响

以氮等离子体为氮源,以三乙基镓（TEG）为镓源,在蓝宝石（Al2O3）衬底上生长GaN缓冲层。主要考察了氮化温度和氮气流量对缓冲层生长的影响。实验中采用了氢氮混合等离子体清洗的方法,提高了清洗的质量。用X射线衍射来表征晶体的结构,用原子力显微镜来表征表面形貌。通过对高能电子衍射仪获得的缓冲层与氮化层的衍射图样进行比较,对GaN的氮化实验参数进行了优化。