缓冲层InxGa_(1-x)As组分对In_(0.82)Ga_(0.18)As结晶质量和表面形貌的影响

Effect of the In_xGa_(1-x)As Buffer Layer Compositions on Crystalline Quality and Surface Morphology of In_ (0.82)Ga_ (0.18)As Grown by Low Pressure MOCVD

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In0.82Ga0.18As材料。研究缓冲层InxGa1-xAs的In组分对In0.82Ga0.18As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InxGa1-xAs的In组分影响高温生长的外延层In0.82Ga0.18As的结晶质量和表面形貌。测量得到四个样品的外延层In0.82Ga0.18As的X射线衍射谱峰半峰全宽(FWHM)为0.596°,0.468°,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。

The InxGa1-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 InxGa1-x As detectors, the most important applications are spectral imaging including earth observation, remote sensing and environmental monitoring, etc. The InxGa1-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 In0. 82 Ga0.18 As 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 InxGa1-xAs buffer layer, In0. 82 Ga0.18 As epilayer with thickness of 1 μm was deposited. It was observed that the different In composition of InxGa1-xAs buffer layer influence on crystalline quality and surface morphology of In0. 82 Ga0.18 As epilayer. The crystalline quality of the epilayer materials was characterized by X-ray diffraction （XRD）. In our experiment, the In composition of the InxGa1-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 In0. 82 Ga0.18 As 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 In0. 82 Ga0.18 As 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 InxGa1-xAs buffer can influence on the surface morphology of the In0. 82 Ga0.18 Ass epilayer. The experiments show the crystalline quality and the surface morphology of the In0. 82 Ga0.18 As epilayer is optimum when the In composition of buffer layer is the same as that of the epilayer.