采用气态源分子束外延方法生长了三种不同结构的扩展波长(室温下50%截止波长为2.4μm)InxGa1-xAs光电探测器材料,并制成了台面型器件.材料的表面形貌、X射线衍射摇摆曲线及光致发光谱表明,在InAlAs/In-GaAs异质界面处生长数字梯度超晶格可以明显提高材料质量;器件在室温下的暗电流结果显示,直径为300μm的器件在反向偏压为10mV时,没有生长超晶格结构的器件暗电流为0.521μA,而生长超晶格结构的器件暗电流降到0.480μA.同时,在生长InxAl1-xAs组分线性渐变缓冲层之前首先生长一层InP缓冲层也有利于改善材料质量和器件性能.

The materials of extended wavelength InxGa1-xAs photodetectors (50% cut-off wavelength of 2.4μm at room temperature) with three different structures were grown by using gas source molecular beam epitaxy (GSMBE) and were processed into mesa type photodetectors. Surface morphology, x-ray diffraction rocking curve and photolnminescence measurements show that the quality of materials is obviously improved by using digital graded superlattice at the InAlAs/InGaAs heterointerfaces . The dark current at reverse bias of 10mV for the 300μm-diameter mesa type photodetectors without digital graded superlattice is 0.521μA at room temperature, however it is reduced to 0.480μA for photodetectors with digital graded superlattice. Besides, the growth of an InP buffer layer between InP substrate and InxAl1-xAs linear graded buffer layer is also beneficial to the material quality and device performance.