A series of metamorphic high electron mobility transistors （MMHEMTs） with different Ⅴ/Ⅲ flux ratios are grown on CaAs （001） substrates by molecular beam epitaxy （MBE）. The samples are analysed by using atomic ...A series of metamorphic high electron mobility transistors （MMHEMTs） with different Ⅴ/Ⅲ flux ratios are grown on CaAs （001） substrates by molecular beam epitaxy （MBE）. The samples are analysed by using atomic force microscopy （AFM）, Hall measurement, and low temperature photoluminescence （PL）. The optimum Ⅴ/Ⅲ ratio in a range from 15 to 60 for the growth of MMHEMTs is found to be around 40. At this ratio, the root mean square （RMS） roughness of the material is only 2.02 nm; a room-temperature mobility and a sheet electron density are obtained to be 10610.0cm^2/（V.s） and 3.26×10^12cm^-2 respectively. These results are equivalent to those obtained for the same structure grown on InP substrate. There are two peaks in the PL spectrum of the structure, corresponding to two sub-energy levels of the In0.53Ga0.47As quantum well. It is found that the photoluminescence intensities of the two peaks vary with the Ⅴ/Ⅲ ratio, for which the reasons are discussed.展开更多
Five-period AlGaSb/GaSb multiple quantum wells（MQW） are grown on a GaSb buffer.Through optimizing the AlSb nucleation layer,the low threading dislocation density of the MQW is found to be（2.50±0.91）×10~8...Five-period AlGaSb/GaSb multiple quantum wells（MQW） are grown on a GaSb buffer.Through optimizing the AlSb nucleation layer,the low threading dislocation density of the MQW is found to be（2.50±0.91）×10~8 cm^（-2） in 1-μm GaSb buffer,as determined by plan-view transmission election microscopy（TEM） images.High resolution TEM clearly shows the presence of 90°misfit dislocations with an average spacing of 5.4 nm at the AlSb/GaAs interface,which effectively relieve most of the strain energy.In the temperature range from T = 26 K to 300 K,photoluminescence of the MQW is dominated by the ground state electron to ground state heavy hole（el-hhl） transition, while a high energy shoulder clearly seen at T76 K can be attributed to the ground state electron to ground state light hole（el-lhl） transition.展开更多
文摘A series of metamorphic high electron mobility transistors （MMHEMTs） with different Ⅴ/Ⅲ flux ratios are grown on CaAs （001） substrates by molecular beam epitaxy （MBE）. The samples are analysed by using atomic force microscopy （AFM）, Hall measurement, and low temperature photoluminescence （PL）. The optimum Ⅴ/Ⅲ ratio in a range from 15 to 60 for the growth of MMHEMTs is found to be around 40. At this ratio, the root mean square （RMS） roughness of the material is only 2.02 nm; a room-temperature mobility and a sheet electron density are obtained to be 10610.0cm^2/（V.s） and 3.26×10^12cm^-2 respectively. These results are equivalent to those obtained for the same structure grown on InP substrate. There are two peaks in the PL spectrum of the structure, corresponding to two sub-energy levels of the In0.53Ga0.47As quantum well. It is found that the photoluminescence intensities of the two peaks vary with the Ⅴ/Ⅲ ratio, for which the reasons are discussed.
基金supported by the National Natural Science Foundation of China(No.50572120)the National High Technology Research and Development Program of China(No.2009AA033101)the State Key Development for Basic Research of China(No.2010CB327501).
文摘Five-period AlGaSb/GaSb multiple quantum wells（MQW） are grown on a GaSb buffer.Through optimizing the AlSb nucleation layer,the low threading dislocation density of the MQW is found to be（2.50±0.91）×10~8 cm^（-2） in 1-μm GaSb buffer,as determined by plan-view transmission election microscopy（TEM） images.High resolution TEM clearly shows the presence of 90°misfit dislocations with an average spacing of 5.4 nm at the AlSb/GaAs interface,which effectively relieve most of the strain energy.In the temperature range from T = 26 K to 300 K,photoluminescence of the MQW is dominated by the ground state electron to ground state heavy hole（el-hhl） transition, while a high energy shoulder clearly seen at T76 K can be attributed to the ground state electron to ground state light hole（el-lhl） transition.
