利用气态源分子束外延, 采用相对较高的1.1%μm-1失配度变化速率, 在InAlAs递变缓冲层上生长了晶格失配度高达2.6%的InP基InGaAs变形晶格探测器结构, 并与采用相同结构而晶格失配度为1.7%和2.1%的探测器样品进行了比较。通过原子力显微镜、X射线衍射、光致发光和器件特性测试对样品进行了表征。结果显示该晶格失配度达2.6%的探测器结构具有较好的表面形貌、较大的晶格弛豫度和理想的光学特性。器件室温截止波长约为2.9μm, 直径为300μm的器件室温下在反向偏压10mV时的暗电流为2.56μA。

InP-based metamorphic InGaAs photodetector structures with lattice mismatch up to 2.6% were grown on InAlAs graded buffers with a relatively high mismatch grading rate of 1.1%μm-1 by gas source molecular beam epitaxy. They were compared to the samples with the same structures but smaller lattice mismatch of 1.7% and 2.1% to the InP substrate. Characteristics of the wafers were investigated by the measurements of atomic force microscopy, x-ray diffraction, photoluminescence and device performances. Results show that moderate surface morphology, large degree of relaxation and feasible optical characteristics have been obtained for the photodetector structures with lattice mismatch of 2.6%. The cut-off wavelength of the device is about 2.9μm at room temperature. The typical dark current of 2.56μA at room temperature has been achieved at reverse bias of 10 mV for the photodetector with 300 μm diameter.