Microstructures of GaN buffer layers grown on Si(111)substrates using rapid thermal process low-pressure metalorganic chemical vapor deposition are investigated by an atomic force microscope(AFM)and a high-resolution ...Microstructures of GaN buffer layers grown on Si(111)substrates using rapid thermal process low-pressure metalorganic chemical vapor deposition are investigated by an atomic force microscope(AFM)and a high-resolution transmission electron microscope(HBTEM).AFM images show that the islands appear in the GaN buffer layer after annealing at high temperature.Cross-sectional HBTEM micrographs of the buffer region of these samples indicate that there are bunched steps on the surface of the Si substrate and a lot of domains in GaN misorienting each other with small angles.The boundaries of those domains locate near the bunched steps,and the regions of the Him on a terrace between steps have the same crystal orientation.An amorphous-like layer,about 3nm thick,can also be observed between the GaN buffer layer and the Si substrate.展开更多
AlGaN/GaN heterostructures on sapphire substrate were fabricated by using light radiation heating metalor ganic chemical vapor deposition.Photoluminescence excitation spectra show that there are two abrupt slopes corr...AlGaN/GaN heterostructures on sapphire substrate were fabricated by using light radiation heating metalor ganic chemical vapor deposition.Photoluminescence excitation spectra show that there are two abrupt slopes corresponding to the absorption edges of AlGaN and GaN,respectively.X-ray diffraction spectra clearly exhibit the GaN(0002),(0004),and A1GaN(0002),(0004)diffraction peaks,and no diffraction peak other than those from the GaN{0001}and A1GaN{0001}planes is found.Reciprocal space mapping indicates that there is no tilt between the AlGaN layer and the GaN layer.All results also indicate that the sample is of sound quality and the Al composition in the AlGaN layer is of high uniformity.展开更多
基金Supported by Project of High Technology Research&Development of China(863-715-011-0030),Project of Fundamental Research of China,the National Natural Science Foundation of China under Grant Nos.69636010 and 69636040,and MOTOROLA(China Inc.)Semiconductor Scholarship.
文摘Microstructures of GaN buffer layers grown on Si(111)substrates using rapid thermal process low-pressure metalorganic chemical vapor deposition are investigated by an atomic force microscope(AFM)and a high-resolution transmission electron microscope(HBTEM).AFM images show that the islands appear in the GaN buffer layer after annealing at high temperature.Cross-sectional HBTEM micrographs of the buffer region of these samples indicate that there are bunched steps on the surface of the Si substrate and a lot of domains in GaN misorienting each other with small angles.The boundaries of those domains locate near the bunched steps,and the regions of the Him on a terrace between steps have the same crystal orientation.An amorphous-like layer,about 3nm thick,can also be observed between the GaN buffer layer and the Si substrate.
基金Supported by the National Natural Science Foundation of China under Grant Nos.69806006,69636010 and 69987001the National High Technology Research&Development Project of China(863-715-011-0030).
文摘AlGaN/GaN heterostructures on sapphire substrate were fabricated by using light radiation heating metalor ganic chemical vapor deposition.Photoluminescence excitation spectra show that there are two abrupt slopes corresponding to the absorption edges of AlGaN and GaN,respectively.X-ray diffraction spectra clearly exhibit the GaN(0002),(0004),and A1GaN(0002),(0004)diffraction peaks,and no diffraction peak other than those from the GaN{0001}and A1GaN{0001}planes is found.Reciprocal space mapping indicates that there is no tilt between the AlGaN layer and the GaN layer.All results also indicate that the sample is of sound quality and the Al composition in the AlGaN layer is of high uniformity.
