Ga_xIn_(1-x)As_(1-y)Sb_y合金的MOCVD生长

GROWTH OF GaxIn_(1-x)As_(1-y)Sb_y ALLOYSBY MOCVD AND CHARACTERIZATION

用水平常压MOCVD系统生长了2—4μm波段的Ga_xIn_(1-x)As_(1-y)Sb_y合金.气相源包括三甲基镓、三甲基铟,三甲基锑(TMGa、TMIn、TMSb)及砷烷(AsH_3).研究了富GaSb的Ga_xIn_(1-x)As_(1-y)Sb_y的生长特性.发现Ⅴ族源输入绝对量影响Ⅴ族元素的分布系数及Ⅲ族源的利用效率.这表明表面反应动力学对生长有一定影响.固相组分由微电子探针测量.用光致发光、红外吸收技术对合金进行了表征.光致发光光谱半高宽,在2.13μm处仅为30meV.用光致发光,红外吸收测量的结果导出四元合金的带隙G_g~∞,并由组分x,y计算了带隙,实验和计算的结果符合得很好.PL谱半高宽较宽和红外吸收谱的吸收边较缓是可能在固相中存在组分群造成的.

GaxIn1+xAs1-ysby alloys in GaSb-rich conner have been grown on the GaSb and GaAs substrates by Metalorganic Chemical Vapor Deposition (MOCVD) in a horizontal, atmospheric pressure reactor. The reac-tants included trimethylgallium (TMGa) , trimethylindium (TMIn),arsine (AsH3) and phosphine (PH3). The composition of epi-layer was determined by electron microprobe. It was observed that the composition y of solid depended on the ratio of PTMsb to (PTMsb + PASH3) in vapor phase, but also on the AsH3 flow rate of vapor source, and the growth rate for per molar 3333333333 group source increased with growth temperature below 620??CCCCCCCCC. It indicated that the growth is influenced by surface kinetics.For some samples, measurements of photoluminescence (PL) at 7lK and infrared absorption at 300K were carried out. The PL spectrum half width AAAAAAAAAE = 30meV was obtained for a sample with peak wavelength RRRRRRRRp = 2.1UUUUUUUUm. The energy gap of GaxIn1-xAS1-ySbv was determined from the PL peak or infrared absorption spectra . The relation of energy gap Eg to composition for GaxIn1-xAs1-ySby were calculated using the Moon's model for GalnAsP and the calculation results of E g are in good agreement with the that of measurements. Larger FWHM of the PL peak and the extended tail of infrared absorption spectra may be results from larger lattice mismatch and composition clustering in solid,