共查询到20条相似文献,搜索用时 0 毫秒
1.
Xu Zhihao Zhang Jincheng Duan Huantao Zhang Zhongfen Zhu Qingwei Xu Hao Hao Yue 《半导体学报》2009,30(12):123003-123003-5
The stresses, structural and electrical properties of n-type Si-doped GaN films grown by metalorganic chemical vapor deposition (MOCVD) are systemically studied. It is suggested that the main stress relaxation is induced by bending dislocations in low doping samples. But for higher doping samples, as the Si doping concentration increases, the in-plane stresses in the grown films are quickly relaxed due to the rapid increase of the edge dislocation densities. Hall effect measurements reveal that the carrier mobility first increases rapidly and then decreases with increasing Si doping concentration. This phenomenon is attributed to the interaction between various scattering process. It is suggested that the dominant scattering process is defect scattering for low doping samples and ionized impurity scattering for high doping samples. 相似文献
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The stresses, structural and electrical properties of n-type Si-doped GaN films grown by metaiorganic chemical vapor deposition (MOCVD) are systemically studied. It is suggested that the main stress relaxation is induced by bending dislocations in low doping samples. But for higher doping samples, as the Si doping concentration increases, the in-plane stresses in the grown films are quickly relaxed due to the rapid increase of the edge dislocation densities. Hall effect measurements reveal that the carrier mobility first increases rapidly and then decreases with increasing Si doping concentration. This phenomenon is attributed to the interaction between various scattering process. It is suggested that the dominant scattering process is defect scattering for low doping samples and ionized impurity scattering for high doping samples. 相似文献
3.
采用不同厚度AlN作为缓冲层在6H-SiC衬底上生长了GaN外延层,并利用X射线衍射,拉曼散射和透射电子显微镜等对GaN性质进行了研究。AlN缓冲层的应变状态对GaN的晶体质量和表面形貌有很大影响。较厚的AlN缓冲层会导致GaN表面出现裂纹,而太薄的AlN缓冲层会导致GaN层较高的位错密度,从而恶化器件性能。分析了GaN产生裂纹和高位错密度的机制,并采用较优厚度(100nm)的AlN缓冲层生长出高质量的GaN外延层。 相似文献
4.
Ding Guojian Guo Liwei Xing Zhigang Chen Yao Xu Peiqiang Jia Haiqiang Zhou Junming Chen Hong 《半导体学报》2010,31(3):033003-033003-5
Characteristics of GaN grown on 6H-SiC (0001) substrates using different thicknesses of AlN buffers are studied. It is found that the surface morphology and crystal quality of GaN film closely depends on the strain state of the AlN buffer. For a thicker AlN buffer, there are cracks on GaN surface, which make the GaN films unsuitable for applications. While for a thinner AlN buffer, more dislocations are produced in the GaN film, which deteriorates the performance of GaN. Possible generation mechanisms of cracks and more dislocations are investigated and a ~100 nm AlN buffer is suggested to be a better choice for high quality GaN on SiC. 相似文献
5.
对掺杂浓度为1017~1019cm-3的GaN:Si样品进行高精度X射线衍射和拉曼散射光谱的研究发现:随着Si掺杂浓度的增加,GaN晶粒尺寸逐渐减小,引发更多的螺位错和混合位错致使摇摆曲线的半高宽有所增加,同时薄膜中的剩余应力也逐渐减小。当掺杂浓度高于2.74×1018cm-3时,薄膜从压力状态转变为张力状态。 相似文献
6.
LIAO Xiu-ying ZHU Yan-ling YANG Xiao-bo ZHAO Hong ZHAO Wen-bo ZHOU Xun ZOU Ze-ya ZENG Qing-gao 《半导体光子学与技术》2008,14(4):224-228
The crystal quality of p-GaN film depends on the stress-strain during the process of material growth at a certain extent. A smooth high-quality GaN epitaxial layer was grown on sapphire substrate using standard low-temperature(LT) buffer layer by MOCVD. And by testing analysis of correlative experiments, we found that the stress-strain of p-type GaN could be changed by annealing, enhancing the crystal quality. 相似文献
7.
Growth of GaN on porous SiC and GaN substrates 总被引:1,自引:0,他引:1
C. K. Inoki T. S. Kuan C. D. Lee Ashutosh Sagar R. M. Feenstra D. D. Koleske D. J. Díaz P. W. Bohn I. Adesida 《Journal of Electronic Materials》2003,32(8):855-860
We have studied the growth of GaN on porous SiC and GaN substrates, employing both plasma-assisted molecular-beam epitaxy
(PAMBE) and metal-organic chemical-vapor deposition (MOCVD). For growth on porous SiC, transmission electron microscopy (TEM)
observations indicate that the epitaxial-GaN growth initiates primarily from surface areas between pores, and the exposed
surface pores tend to extend into GaN as open tubes and trap Ga droplets. The dislocation density in the GaN layers is similar
to, or slightly less than, that observed in layers grown on nonporous substrates. For the case of GaN growth on porous GaN,
the overgrown layer replicates the underlying dislocation structure (although considerable dislocation reduction can occur
as this overgrowth proceeds, independent of the presence of the porous layer). The GaN layers grown on a porous SiC substrate
were found to be mechanically more relaxed than those grown on nonporous substrates; electron-diffraction patterns indicate
that the former are free of misfit strain or are even in tension after cooling to room temperature. 相似文献
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Si-doped GaN epitaxial layers have been grown at 1050 °C on optimized-AlN buffered (0001) sapphire substrates by atmospheric pressure metalorganic vapor phase epitaxy. In order to investigate the Si effect on the surface morphology of GaN epilayers, several samples were grown by varying the silane partial pressure. When the silane partial pressure increases above 1.7×10−8 atm, the surface quality becomes rough. This shows the Si surfactant effect. A correlation between an in situ laser reflectometry and ex situ optical and atomic force microscopy characterizations on the one hand and between electrical properties and surface quality on the other hand were made. As the electron concentration increases, the surface becomes more and more rough and the mobility drops dramatically. 相似文献
10.
T. Paskova V. Darakchieva E. Valcheva P. P. Paskov I. G. Ivanov B. Monemar T. Böttcher C. Roder D. Hommel 《Journal of Electronic Materials》2004,33(5):389-394
The strain distribution in thick hydride vapor-phase epitaxial (HVPE)-GaN layers grown on metal-organic vapor-phase epitaxial
GaN templates was studied by means of photoluminescence, x-ray mapping, and lattice parameter analysis. A variable temperature
x-ray study of the film curvature was used for verification of the strain type. The relation between the strain inhomogeneity
and the wafer bending in films residing on sapphire and freestanding on the thickness of the layer and the substrate is analyzed.
Possibilities to improve the uniformity of the film characteristics and to reduce the bending of the HVPE-GaN films are discussed. 相似文献
11.
从Ⅲ-Ⅴ族氮化物半导体压电极化对应变的依赖关系出发,采用有限元方法计算了GaN/AIN量子点结构中的应变分布,研究了其自发极化、压电极化以及极化电荷密度.结果表明,应变导致的压电极化和Ⅲ-Ⅴ族氮化物半导体所特有的自发极化将导致电荷分布的变化,使电子聚集在量子点顶部,空穴聚集在量子点下面的湿润层中,在量子点结构中产生显著的极化电场,并讨论了电场的存在对能带带边的形状以及能级分布的影响. 相似文献
12.
从Ⅲ-Ⅴ族氮化物半导体压电极化对应变的依赖关系出发,采用有限元方法计算了GaN/AlN量子点结构中的应变分布,研究了其自发极化、压电极化以及极化电荷密度.结果表明,应变导致的压电极化和Ⅲ-Ⅴ族氮化物半导体所特有的自发极化将导致电荷分布的变化,使电子聚集在量子点顶部,空穴聚集在量子点下面的湿润层中,在量子点结构中产生显著的极化电场,并讨论了电场的存在对能带带边的形状以及能级分布的影响. 相似文献
13.
从Ⅲ-Ⅴ族氮化物半导体压电极化对应变的依赖关系出发,采用有限元方法计算了GaN/AlN量子点结构中的应变分布,研究了其自发极化、压电极化以及极化电荷密度.结果表明,应变导致的压电极化和Ⅲ-Ⅴ族氮化物半导体所特有的自发极化将导致电荷分布的变化,使电子聚集在量子点顶部,空穴聚集在量子点下面的湿润层中,在量子点结构中产生显著的极化电场,并讨论了电场的存在对能带带边的形状以及能级分布的影响. 相似文献
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Si-doped GaN layers have been grown using SiN treatment growth by MOVPE on sapphire (0 0 0 1) in a homemade vertical reactor. The growth was monitored by in situ laser reflectometry. The growth temperature was varied between 1090 and 1150 °C, keeping constant all the other parameters. The layers reveal a smooth surface morphology. The room temperature electron concentration is nearly constant about 2×1018 cm−3 with a constant SiH4 flow of 1 nmol/min. The growth rate decreases slowly. Thermodynamic analysis of the growth temperature effect was investigated. To this aim, equilibrium calculations have been performed using the GEMINI code. The experimental growth conditions are used for the calculations. The results show that the important species in the vapor phase are SiNH, SiH4 and SiH2. Two growth regimes are revealed with a critical temperature (Tc) of about 1220 K. For the higher temperature (T>Tc), the partial pressure of SiH4 and SiH2 decreases and increases, respectively, as well as that of SiNH remains constant. We tentatively correlated the experimental and the calculation results based on the fact that the GaN growth temperature is usually higher than Tc. Thus, the evolution of the electron concentration is due to the SiNH species and the growth rate reduction is related to the GaN decomposition. A chemical reaction of the Si-doped GaN with SiH4 as Si precursor is proposed. 相似文献
16.
在自制的立式氢化物气相外延(HVPE)系统炉中,一定温度下通入一定流量的NH3使GaAs(111)衬底氮化一层GaN薄膜,以防止高温外延生长GaN时GaAs分解,进而提高了之后GaN外延生长的晶体质量。实验主要通过XRD检测氮化层的质量,研究了氮化温度和时间对氮化层的影响。实验发现,氮化温度过高会使GaAs表面分解,氮化层为多晶。氮化时间过短,氮化层致密性低,不能起到保护衬底的作用;时间过长则氮化层质量降低,GaN(002)半高宽(FWHM)较大。分析结果表明,在500℃氮化2min的工艺条件下,获得的氮化层质量相比其他条件较好,致密性高。 相似文献
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Yiyao Peng Junfeng Lu Dengfeng Peng Wenda Ma Fangtao Li Qiushuo Chen Xiandi Wang Junlu Sun Haitao Liu Caofeng Pan 《Advanced functional materials》2019,29(42)
The continuous development of strain sensors offers significant opportunities for improving human–machine interfaces and health monitoring. The dynamically modulated lasing mode is a novel approach to realize a flexible, noncontact, high color‐resolvability, high‐resolution, and ultrasensitive strain sensor. Here, a flexible strain sensor perceiving stress variations is reported via the dynamical regulation of a GaN whispering gallery lasing mode based on the piezoelectric effect. The refraction index of GaN shows a linear relationship with the applied external tensile strain, resulting in a redshift phenomenon of the lasing mode peak at room temperature due to the predominant function of the piezoelectric polarization in the GaN microwire. Compared with a strain sensor relying on the wavelength shift of a photoluminescence (PL) emission peak, the differences and advantages of a sensor based on the strain‐induced lasing mode variation are also investigated and analyzed systematically. This strain sensor may serve as an essential step toward the color mapping of mechanical signals by optical methods, with potential applications in color‐perceived touching sensing, noncontact stress measurement, laser modulation, and optical communication technologies. 相似文献
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V. Rajagopal Reddy M. Sivapratap Reddy P. Koteswara Rao 《Microelectronic Engineering》2010,87(2):117-121
Rapid thermal annealing effects on deep level defects in the n-type GaN layer grown by metalorganic chemical vapor deposition (MOCVD) have been characterized using deep level transient spectroscopy (DLTS) technique. The samples were first characterized by current-voltage (I-V) and capacitance-voltage (C-V) measurements. The measurements showed that the barrier height of the as-grown sample to be 0.74 eV (I-V) and 0.95 eV (C-V) respectively. However, the Schottky barrier height of the sample annealed at 800 °C increased to 0.84 eV (I-V) and 0.99 eV (C-V) respectively in nitrogen atmosphere for 1 min. Further, it was observed that the Schottky barrier height slightly decreased after annealing at 900 °C. DLTS results showed that the two deep levels are identified in as-grown sample (E1 and E3), which have activation energies of 0.19 ± 0.01 eV and 0.80 ± 0.01 eV with capture cross-sections 2.06 × 10−17 cm2 and 7.68 × 10−18 cm2, which can be related to point defects. After annealing at 700 °C, the appearance of one new peak (E2) at activation energy of 0.49 ± 0.02 eV with capture-cross section σn = 5.43 × 10−17 cm2, suggest that E2 level is most probably associated with the nitrogen antisites. Thermal annealing at 800 °C caused the E1 and E3 levels to be annealed out, which suggest that they are most probably associated with the point defects. After annealing at 900 °C the same (E1 and E3) deep levels are identified, which were identified in as-grown n-GaN layer. 相似文献