We investigated the quantum dots-templated growth of a（0001） GaN film on a c-plane sapphire substrate.The growth was carried out in a radio-frequency molecular beam epitaxy system.The enlargement and coalescence of ...We investigated the quantum dots-templated growth of a（0001） GaN film on a c-plane sapphire substrate.The growth was carried out in a radio-frequency molecular beam epitaxy system.The enlargement and coalescence of grains on the GaN quantum dots template was observed in the atom force microscopy images,as well as the more ideal surface morphology of the GaN epitaxial film on the quantum dots template compared with the one on the AlN buffer.The Ga polarity was confirmed by the reflected high energy electron diffraction patterns and the Raman spectra.The significant strain relaxation in the quantum dots-templated GaN film was calculated based on the Raman spectra and the X-ray rocking curves.Meanwhile,the threading dislocation density in the quantum dots-templated film was estimated to be 7.1×107cm-2,which was significantly suppressed compared with that of the AlN-buffered GaN film.The roomtemperature Hall measurement showed an electron mobility of up to 1860cm2 /V·s in the two-dimensional electron gas at the interface of the Al 0.25Ga0.75 N/GaN heterojunction.展开更多
GaAs nanowires(NWs)are grown on GaAs(311)B substrates by gold assisted molecular beam epitaxy technology.Combined scanning and transmission electron microscopy analyses,the crystallographic orientations of NWs are stu...GaAs nanowires(NWs)are grown on GaAs(311)B substrates by gold assisted molecular beam epitaxy technology.Combined scanning and transmission electron microscopy analyses,the crystallographic orientations of NWs are studied.It is found that crystallographic orientations of NWs are closely related to their crystal structures:NWs of zinc blende structure grow along<001>directions and NWs of wurtzite structure grow along<0001>directions.The influence of impinging Ga flux on morphology and crystal structure of the NWs is also discussed.It is observed that NWs prefer to grow along zinc blende<001>directions at lower Ga flux,while NWs tend to grow along the wurtzite<0001>directions with only a small portion along the zinc blende<001>direction at a higher Ga flux.The control of crystal structure and orientation of NWs can be achieved effectively by changing the Ga flux.展开更多
基金Project supported by the National Natural Science Foundation of China (Grant No. 1179042)
文摘We investigated the quantum dots-templated growth of a（0001） GaN film on a c-plane sapphire substrate.The growth was carried out in a radio-frequency molecular beam epitaxy system.The enlargement and coalescence of grains on the GaN quantum dots template was observed in the atom force microscopy images,as well as the more ideal surface morphology of the GaN epitaxial film on the quantum dots template compared with the one on the AlN buffer.The Ga polarity was confirmed by the reflected high energy electron diffraction patterns and the Raman spectra.The significant strain relaxation in the quantum dots-templated GaN film was calculated based on the Raman spectra and the X-ray rocking curves.Meanwhile,the threading dislocation density in the quantum dots-templated film was estimated to be 7.1×107cm-2,which was significantly suppressed compared with that of the AlN-buffered GaN film.The roomtemperature Hall measurement showed an electron mobility of up to 1860cm2 /V·s in the two-dimensional electron gas at the interface of the Al 0.25Ga0.75 N/GaN heterojunction.
基金Supported by the Preferred Foundation of Director of Hefei Institute of Solid Physics,Chinese Academy of Sciencesthe National Natural Science Foundation of China under Grant Nos 11179042,11104271.
文摘GaAs nanowires(NWs)are grown on GaAs(311)B substrates by gold assisted molecular beam epitaxy technology.Combined scanning and transmission electron microscopy analyses,the crystallographic orientations of NWs are studied.It is found that crystallographic orientations of NWs are closely related to their crystal structures:NWs of zinc blende structure grow along<001>directions and NWs of wurtzite structure grow along<0001>directions.The influence of impinging Ga flux on morphology and crystal structure of the NWs is also discussed.It is observed that NWs prefer to grow along zinc blende<001>directions at lower Ga flux,while NWs tend to grow along the wurtzite<0001>directions with only a small portion along the zinc blende<001>direction at a higher Ga flux.The control of crystal structure and orientation of NWs can be achieved effectively by changing the Ga flux.
