共查询到20条相似文献,搜索用时 46 毫秒
1.
Influence of AlN Buffer Thickness on GaN Grown on Si(111) by Gas Source Molecular Beam Epitaxy with Ammonia
下载免费PDF全文
![点击此处可从《中国物理快报》网站下载免费的PDF全文](/ch/ext_images/free.gif)
Hexagonal GaN is grown on a Si(111) substrate with AlN as a buffer layer by gas source molecular beam epitaxy (GSMBE) with ammonia. The thickness of AlN buffer is changed from 9 to 72nm. When the thickness of AlN buffer is 36nm, the surface morphology and crystal quality of GaN is optimal. The in-situ reflection high energy electron diffraction (RHEED) reveals that the transition to a two-dimensional growth mode of AlN is the key to the quality of GaN. However, the thickness of AlN buffer is not so critical to the residual in-plane tensile stress in GaN grown on Si(111) by GSMBE for AlN thickness between 9 to 72nm. 相似文献
2.
N. Chaaben J. Yahyaoui M. Christophersen T. Boufaden B. El Jani 《Superlattices and Microstructures》2006,40(4-6):483
Metal Organic Vapour Phase Epitaxy (MOVPE) of AlN and GaN layers at a temperature of 1080 C were performed on porous Si(111) and Si(111) substrates. The thermal stability of porous silicon (PS) is studied versus growth time under AlN and GaN growth conditions. The surface morphology evolution of the annealed PS is revealed by scanning electron microscopy (SEM). Porous Si(111) with low porosity (40%) is more thermally stable than porous Si(100) with relatively high porosity (60%).AlN layers with various thicknesses were grown under the same conditions on the two substrates. Morphological properties of AlN were studied by atomic force microscopy (AFM) and compared taking into account the two different surfaces of the substrates. The two growth kinetics of AlN were found to be different due to the initial surface roughness of the PS substrate. The effect of AlN buffer morphology on the qualities of subsequent GaN layers is discussed. Morphological qualities of GaN layers grown on PS are improved compared to those obtained on porous Si(100) but are still less than those grown on Si substrate. 相似文献
3.
利用卢瑟福背散射/沟道技术和高分辨率X射线衍射技术对在Si(111)衬底上利用金属有机化合物气相外延技术(MOVPE)生长有多缓冲层的六方GaN外延膜进行结晶品质计算、晶格常数计算和应变分析. 实验结果表明:GaN外延膜的结晶品质为χmin=1.54%,已达到完美晶体的结晶品质(χmin=1%—2%);GaN外延膜的水平方向和垂直方向晶格常数分别为:aepi=0.31903nm,cepi=0.51837nm,基本达到G
关键词:
GaN
高分辨X射线衍射
卢瑟福背散射/沟道
弹性应变 相似文献
4.
GaN and AlN nanowires (NWs) have attracted great interests for the fabrication of novel nano-sized devices. In this paper, the nucleation processes of GaN and AlN NWs grown on Si substrates by molecular beam epitaxy (MBE) are investigated. It is found that GaN NWs nucleated on in-situ formed Si3N4 fully release the stress upon the interface between GaN NW and amorphous Si3N4 layer, while AlN NWs nucleated by aluminization process gradually release the stress during growth. Depending on the strain status as well as the migration ability of III group adatoms, the different growth kinetics of GaN and AlN NWs result in different NW morphologies, i.e., GaN NWs with uniform radii and AlN NWs with tapered bases. 相似文献
5.
通过对GaN基异质结材料C-V特性中耗尽电容的比较,得出AlGaN/GaN异质结缓冲层漏电与成核层的关系.实验结果表明,基于蓝宝石衬底低温GaN成核层和SiC衬底高温AlN成核层的异质结材料比基于蓝宝石衬底低温AlN成核层异质结材料漏电小、背景载流子浓度低.深入分析发现,基于薄成核层的异质结材料在近衬底的GaN缓冲层中具有高浓度的n型GaN导电层,而基于厚成核层的异质结材料的GaN缓冲层则呈高阻特性.GaN缓冲层中的n型导电层是导致器件漏电主要因素之一,适当提高成核层的质量和厚度可有效降低GaN缓冲层的背景载流子浓度,提高GaN缓冲层的高阻特性,抑制缓冲层漏电.
关键词:
AlGaN/GaN异质结
GaN缓冲层
漏电
成核层 相似文献
6.
Influence of AlN buffer layer thickness on structural properties of GaN epilayer grown on Si (111) substrate with AlGaN interlayer
下载免费PDF全文
![点击此处可从《中国物理 B》网站下载免费的PDF全文](/ch/ext_images/free.gif)
We present the growth of GaN epilayer on Si (111)
substrate with a single AlGaN interlayer sandwiched between the GaN
epilayer and AlN buffer layer by using the metalorganic chemical
vapour deposition. The influence of the AlN buffer layer thickness
on structural properties of the GaN epilayer has been investigated
by scanning electron microscopy, atomic force microscopy, optical
microscopy and high-resolution x-ray diffraction. It is found that
an AlN buffer layer with the appropriate thickness plays an important
role in increasing compressive strain and improving crystal quality
during the growth of AlGaN interlayer, which can introduce a more
compressive strain into the subsequent grown GaN layer, and
reduce the crack density and threading dislocation density in GaN
film. 相似文献
7.
The influence of AlN/GaN superlattice intermediate layer on the properties of GaN grown on Si(111) substrates
下载免费PDF全文
![点击此处可从《中国物理》网站下载免费的PDF全文](/ch/ext_images/free.gif)
AlN/GaN superlattice buffer is inserted between GaN epitaxial layer
and Si substrate before epitaxial growth of GaN layer. High-quality
and crack-free GaN epitaxial layers can be obtained by inserting
AlN/GaN superlattice buffer layer. The influence of AlN/GaN
superlattice buffer layer on the properties of GaN films are
investigated in this paper. One of the important roles of the
superlattice is to release tensile strain between Si substrate and
epilayer. Raman spectra show a substantial decrease of in-plane
tensile strain in GaN layers by using AlN/GaN superlattice buffer
layer. Moreover, TEM cross-sectional images show that the densities
of both screw and edge dislocations are significantly reduced. The
GaN films grown on Si with the superlattice buffer also have better
surface morphology and optical properties. 相似文献
8.
9.
Polycrystalline GaN thin films have been deposited epitaxially on a ZnO-buffered (111)-oriented Si substrate by molecular beam epitaxy. The microstructural and compositional characteristics of the films were studied by analytical transmission electron microscopy (TEM). A SiO(2) amorphous layer about 3.5 nm in thickness between the Si/ZnO interface has been identified by means of spatially resolved electron energy loss spectroscopy. Cross-sectional and plan-view TEM investigations reveal (GaN/ZnO/SiO(2)/Si) layers exhibiting definite a crystallographic relationship: [111](Si)//[111](ZnO)//[0001](GaN) along the epitaxy direction. GaN films are polycrystalline with nanoscale grains ( approximately 100 nm in size) grown along [0001] direction with about 20 degrees between the (1l00) planes of adjacent grains. A three-dimensional growth mode for the buffer layer and the film is proposed to explain the formation of the as-grown polycrystalline GaN films and the functionality of the buffer layer. 相似文献
10.
采用金属有机化合物化学气相沉积(MOCVD)方法制备了不同AlN缓冲层厚度的GaN样品,研究了AlN缓冲层厚度对GaN外延层的应力、表面形貌和晶体质量的影响。研究结果表明:厚度为15 nm的AlN缓冲层不仅可以有效抑制Si扩散,而且还给GaN外延层提供了一个较大的压应力,避免GaN薄膜出现裂纹。在该厚度AlN缓冲层上制备的GaN薄膜表面光亮、无裂纹,受到的张应力为0.3 GPa,(0002)和(1012)面的高分辨X射线衍射摇摆曲线峰值半高宽分别为536 arcsec和594 arcsec,原子力显微镜测试得到表面粗糙度为0.2 nm。 相似文献
11.
《中国物理 B》2019,(2)
Polycrystalline gallium nitride(GaN) thin films were deposited on Si(100) substrates via plasma-enhanced atomic layer deposition(PEALD) under optimal deposition parameters. In this work, we focus on the research of the GaN/Si(100)interfacial properties. The x-ray reflectivity measurements show the clearly-resolved fringes for all the as-grown GaN films, which reveals a perfectly smooth interface between the GaN film and Si(100), and this feature of sharp interface is further confirmed by high resolution transmission electron microscopy(HRTEM). However, an amorphous interfacial layer(~ 2 nm) can be observed from the HRTEM images, and is determined to be mixture of Ga_xO_y and GaN by xray photoelectron spectroscopy. To investigate the effect of this interlayer on the GaN growth, an AlN buffer layer was employed for GaN deposition. No interlayer is observed between GaN and AlN, and GaN shows better crystallization and lower oxygen impurity during the initial growth stage than the GaN with an interlayer. 相似文献
12.
Optical and structural investigation of a-plane GaN layers on r-plane sapphire with nucleation layer optimization
下载免费PDF全文
![点击此处可从《中国物理 B》网站下载免费的PDF全文](/ch/ext_images/free.gif)
Nonpolar a-plane GaN epilayers are grown on several r-plane sapphire substrates by metal organic chemical vapour deposition using different nucleation layers:(A) a GaN nucleation layer deposited at low temperature(LT);(B) an AlN nucleation layer deposited at high temperature;or(C) an LT thin AlN nucleation layer with an AlN layer and an AlN/AlGaN superlattice both subsequently deposited at high temperature.The samples have been characterized by Xray diffraction(XRD),atomic force microscopy and photoluminescence.The GaN layers grown using nucleation layers B and C show narrower XRD rocking curves than that using nucleation layer A,indicating a reduction in crystal defect density.Furthermore,the GaN layer grown using nucleation layer C exhibits a surface morphology with triangular defect pits eliminated completely.The improved optical property,corresponding to the enhanced crystal quality,is also confirmed by temperature-dependent and excitation power-dependent photoluminescence measurements. 相似文献
13.
14.
人们已提出用BAlGaN四元系材料制备紫外光谱区的光发射器件.GaN和AlN二元系是这种四元材料在器件应用中的基础材料.6H-SiC衬底在氮化物生长中因其晶格失配小是一大优势,而且SiC衬底的热膨胀系数也和AlN的很接近.然而,对于AlN外延层来说,需要控制其中的残余应力,因为在SiC衬底上直接生长的AlN外延层中存在着因晶格失配所产生的压缩应力.另一方面,在SiC衬底上直接生长的GaN外延层中存在着拉伸应力.这种拉伸应力起源于GaN比衬底有着更大的热膨胀系数.本文讨论了在6H-SiC衬底上生长的氮化物外延层中残余应力的类型、数量及控制.为此目的,提出了在6H-SiC衬底上,无论是生长AlN,还是生长GaN,都可以采用(GaN/AlN)多层缓冲层的办法,作为控制残余应力的有效方法.我们还讨论了AlN和GaN外延层的结晶质量和残余应力间的关系. 相似文献
15.
16.
The effect of single A1GaN interlayer on the structural properties of GaN epilayers grown on Si (111) substrates
下载免费PDF全文
![点击此处可从《中国物理 B》网站下载免费的PDF全文](/ch/ext_images/free.gif)
High-quality and nearly crack-free GaN epitaxial layer was obtained
by inserting a single AlGaN interlayer between GaN epilayer and
high-temperature AlN buffer layer on Si (111) substrate by
metalorganic chemical vapor deposition. This paper investigates the
effect of AlGaN interlayer on the structural properties of the
resulting GaN epilayer. It confirms from the optical microscopy and
Raman scattering spectroscopy that the AlGaN interlayer has a
remarkable effect on introducing relative compressive strain to the
top GaN layer and preventing the formation of cracks. X-ray
diffraction and transmission electron microscopy analysis reveal
that a significant reduction in both screw and edge threading
dislocations is achieved in GaN epilayer by the insertion of AlGaN
interlayer. The process of threading dislocation reduction in both
AlGaN interlayer and GaN epilayer is demonstrated. 相似文献
17.
18.
Hasegawa F Soude R 《发光学报》2001,22(4):315-318
研究了在GaAs(111)衬底上生长的六角相GaN的极性的相关关系.在高Ⅴ/Ⅲ比的条件下用MOVPE和MOMBE方法生长的GaN的极性和GaAs衬底的极性一致;在(111)A-Ga表面上的生长层呈现Ga的极性,而在(111)B-As表面上的生长层呈现N的极性.然而,在低的Ⅴ/Ⅲ比,或采用一个AIN中间层的条件下,用HVPE和MOMBE方法在GaAs(111)B表面上生长的GaN呈现出Ga的极性.目前,其原因尚不清楚,但是这些结果表明采用HVPE生长方法或用一高温AlN阻挡层可以得到高质量的GaN. 相似文献
19.
采用金属有机化学气相沉积(MOCVD)技术在Si(111)衬底上外延GaN薄膜,对高温AlN(HT-AlN)缓冲层在小范围内低生长压力(6.7~16.6 kPa)条件下对GaN薄膜特性的影响进行了研究。研究结果表明GaN外延层的表面形貌、结构和光学性质对HT-AlN缓冲层的生长压力有很强的的依赖关系。增加HT-AlN缓冲层的生长压力,GaN薄膜的光学和形貌特性均有明显改善,当HT-AlN缓冲层的生长压力为13.3 kPa时,得到无裂纹的GaN薄膜,其(002)和(102)面的X射线衍射峰值半高宽分别为735 arcsec和778 arcsec,由拉曼光谱计算得到的张应力为0.437 GPa,原子力显微镜(AFM)观测到表面粗糙度为1.57 nm。 相似文献
20.
A method to drastically reduce dislocation density in a GaN film grown on an Si(111) substrate is newly developed. In this method, the SixNy interlayer which is deposited on an AlN buffer layer in situ is introduced to grow the GaN film laterally. The crack-free GaN film with thickness over 1.7 micron is grown on an Si(111) substrate successfully. Synthesized GaN epilayer is characterized by X-ray diffraction (XRD), atomic force microscope (AFM), and Raman spectrum. The test results show that the GaN crystal reveals a wurtzite structure with the <0001> crystal orientation and the full width at half maximum of the X-ray diffraction curve in the (0002) plane is as low as 403 arcsec for the GaN film grown on the Si substrate with an SixNy interlayer. In addition, Raman scattering is used to study the stress in the sample. The results indicate that the SixNy interlayer can more effectively accommodate the strain energy. So the dislocation density can be reduced drastically, and the crystal quality of GaN film can be greatly improved by introducing SixNy interlayer. 相似文献