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Effect of Reactor Pressure on Qualities of GaN Layers Grown by Hydride Vapour Phase Epitaxy 下载免费PDF全文
The influence of reactor pressure on GaN layers grown by hydride vapour phase epitaxy (HVPE) is investigated. By decreasing the reactor pressure from0. 7 to 0.5 mm, the GaN layer growth mode changes from the island-like one to the step flow. The improvements in structural and optical properties and surface morphology of GaN layers are observed in the step flow growth mode. The results clearly indicate that the reactor pressure, similarly to the growth temperature, is One of the important parameters to influence the qualities of GaN epilayers grown by HVPE, due to the change of growth mode. 相似文献
2.
Effect of double AlN buffer layer on the qualities of GaN films grown by radio-frequency molecular beam epitaxy 下载免费PDF全文
This paper reports that the GaN thin films with Ga-polarity and high quality were grown by radio-frequency molecular beam epitaxy on sapphire (0001) substrate with a double A1N buffer layer. The buffer layer consists of a high-temperature (HT) A1N layer and a low-temperature (LT) A1N layer grown at 800℃ and 600℃, respectively. It is demonstrated that the HT-A1N layer can result in the growth of GaN epilayer in Ga-polarity and the LT-A1N layer is helpful for the improvement of the epilayer quality. It is observed that the carrier mobility of the GaN epilayer increases from 458 to 858cm^2/V.s at room temperature when the thickness of LT-A1N layer varies from 0 to 20nm. The full width at half maximum of x-ray rocking curves also demonstrates a substantial improvement in the quality of GaN epilavers by the utilization of LT-A1N layer. 相似文献
3.
Effect of Ⅲ/Ⅴ Ratio of HT-AIN Buffer Layer on Polarity Selection and Electrical Quality of GaN Films Grown by Radio Frequency Molecular Beam Epitaxy 总被引:1,自引:0,他引:1 下载免费PDF全文
We investigate the effect of A/N ratio of the high temperature (HT) AIN buffer layer on polarity selection and electrical quality of GaN films grown by radio frequency molecular beam epitaxy. The results show that low Al/N ratio results in N-polarity GaN films and intermediate Al/N ratio leads to mixed-polarity GaN films with poor electrical quality. GaN films tend to grow with Ga polarity on Al-rich AIN buffer layers. GaN films with different polarities are confirmed by in-situ reflection high-energy electron diffraction during the growth process. Wet chemical etching, together with atomic force microscopy, also proves the polarity assignments. The optimum value for room-temperature Hall mobility of the Ga-polarity GaN film is 703cm^2/V.s, which is superior to the N-polarity and mixed-polarity GaN films. 相似文献
4.
Growth of Strain Free GaN Layers on (0001) Oriented Sapphire by Using Quasi-Porous GaN Template 总被引:1,自引:0,他引:1 下载免费PDF全文
We report the reduced-strain gallium-nitride (GaN) epitaxial growth on (0001) oriented sapphire by using quasiporous GaN template. A GaN film in thickness of about 1 μm was initially grown on a (0001) sapphire substrate by molecular beam epitaxy. Then it was dealt by putting into 45% NaOH solution at 100℃ for lOmin. By this process a quasi-porous GaN film was formed. An epitaxial GaN layer was grown on the porous GaN layer at 1050℃ in the hydride vapour phase epitaxy reactor. The epitaxial layer grown on the porous GaN is found to have no cracks on the surface. That is much improved from many cracks on the surface of the GaN epitaxial layer grown on the sapphire as the same as on GaN buffer directly. 相似文献
5.
通过傅里叶变换红外光谱和光调制反射光谱技术测量了不同Mn含量的低温分子束外延生长在GaAs衬底上的GaMnAs样品的反射光谱.在低于Ga(Mn)As带边的红外反射光谱和光调制反射光谱上观测到低能振荡现象.通过分析振荡产生的原因并使用双层界面反射模型拟合了红外反射光谱的低能振荡过程,拟合结果与实验相符.研究表明,反射光谱的低能振荡是由于GaMnAs中空穴浓度的变化导致GaMnAs中的折射率发生变化,GaMnAs与衬底GaAs之间的折射率差导致了不同Mn含量的GaMnAs材料的反射谱的低能振荡现象.测量了不同
关键词:
GaMnAs
反射光谱
空穴浓度
折射率 相似文献
6.
This paper reports on N-, mixed-, and Ga-polarity buffer layers are
grown by molecular beam epitaxy (MBE) on sapphire (0001) substrates,
with the GaN thicker films grown on the buffer layer with different
polarity by hydride vapour epitaxy technique (HVPE). The surface
morphology, structural and optical properties of these HVPE-GaN
epilayers are characterized by wet chemical etching, scanning
electron microscope, x-ray diffraction, and photoluminescence
spectrum respectively. It finds that the N-polarity film is unstable
against the higher growth temperature and wet chemical etching, while
that of GaN polarity one is stable. The results indicate that the
crystalline quality of HVPE-GaN epilayers depends on the polarity of
buffer layers. 相似文献
7.
GaN layers with different polarities prepared by radio frequency molecular beam epitaxy and characterized by Raman scattering 下载免费PDF全文
GaN layers with different polarities have been prepared by radio-frequency
molecular beam epitaxy (RF-MBE) and characterized by Raman
scattering. Polarity control are realized by controlling
Al/N flux ratio during high temperature AlN buffer growth. The Raman results
illustrate that the N-polarity GaN films have frequency shifts at $A_{1}$(LO)
mode because of their high carrier density; the forbidden $A_{1}$(TO) mode
occurs for mixed-polarity GaN films due to the destroyed translation
symmetry by inversion domain boundaries (IDBS); Raman spectra for
Ga-polarity GaN films show that they have neither frequency shifts mode nor forbidden
mode. These results indicate that Ga-polarity GaN films have a better
quality, and they are in good agreement with the results obtained from the
room temperature Hall mobility. The
best values of Ga-polarity GaN films are 1042 cm$^{2}$/Vs with a carrier
density of 1.0$\times $10$^{17}$~cm$^{ - 3}$. 相似文献
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