缓冲层InxGa1-xAs组分对In0.82Ga0.18As结晶质量和表面形貌的影响

采用低压金属有机化学气相沉积(LP-MOCVD)技术,两步生长法在InP衬底上制备In_0.82Ga_0.18As材料.研究缓冲层In_xGa_1-xAs的In组分对In_0.82Ga_0.18As结晶质量和表面形貌的影响.X射线衍射(XRD)用于表征材料的组分和结晶质量.用扫描电子显微镜(SEM)观察样品的表面形貌.实验结果表明,低温生长的缓冲层In_xGa_1-xAs的In组分影响高温生长的外延层In_0.82Ga_0.18As的结晶质量和表面形貌.测量得到四个样品的外延层In_0.82Ga_0.18As的X射线衍射谱峰半峰全宽(FWHM)为0.596°,0.68°,0.362°和0.391°,分别对应缓冲层In组分x=0.28,0.53,0.82,0.88,当缓冲层In组分是0.82时,FWHM最窄,表明样品的结晶质量最好.SEM观察四个样品的表面形貌,当缓冲层In组分是0.82时,样品的表面平整,没有出现交叉平行线或蚀坑等缺陷,表面形貌最佳.

Effect of the InxGa1-xAs Buffer Layer Compositions on Crystalline Quality and Surface Morphology of In0.82Ga0.18As Grown by Low Pressure MOCVD

The In_xGa_1-xAs material is very important for uncooled infrared detector and has spectral response from 1 μm to 3 μm. In recent years, there are growing needs for high In composition In_xGa_1-xAs detectors, the most important applications are spectral imaging including earth observation, remote sensing and environmental monitoring, etc. The In_xGa_1-xAs (x>0.53) was grown on semi-insulating (100) Fe-doped InP substrates by LP-MOCVD. The growth was performed using TMIn, TMGa, and AsH3 as growth precursors in a horizontal reactor. Two step method of In_0.82Ga_0.18As growth that the buffer layer was grown at low temperature of 450℃ and the epilayer was grown at higher temperature of 530℃ was studied. After depositing 300 nm In_xGa_1-xAs buffer layer, In_0.82Ga_0.18As epilayer with thickness of 1 μm was deposited. It was observed that the different In composition of In_xGa_1-xAs buffer layer influence on crystalline quality and surface morphology of In_0.82Ga_0.18As epilayer. The crystalline quality of the epilayer materials was characterized by X-ray diffraction (XRD). In our experiment, the In composition of the In_xGa_1-xAs buffer layers was 0.28, 0.53, 0.82 and 0.88, respectively. The full-width-at-half-maximum (FWHM) of diffraction peak for the buffer layer of In_0.82Ga_0.18As is 0.362° and is the narrowest among the four samples. The surface morphology was observed by scanning electron microscopy (SEM). The SEM image of the sample with buffer layer of In_0.82Ga_0.18As is a flat surface and is better than other samples with cross-hatches, pits or some defects. We found that the In composition of the In_xGa_1-xAs buffer can influence on the surface morphology of the In_0.82Ga_0.18As epilayer. The experiments show the crystalline quality and the surface morphology of the In_0.82Ga_0.18As epilayer is optimum when the In composition of buffer layer is the same as that of the epilayer.