We investigate epitaxy of AlN layers on sapphire substrates by molecular beam epitaxy.It is found that an atomically flat surface can be obtained under Al-rich conditions at growth temperature of 780°C.However,th...We investigate epitaxy of AlN layers on sapphire substrates by molecular beam epitaxy.It is found that an atomically flat surface can be obtained under Al-rich conditions at growth temperature of 780°C.However,the growth window to obtain an Al−droplet-free surface is too narrow to be well-controlled.However,the growth window can be greatly broadened by increasing the growth temperature up to 950°C,where an Al-droplet-free surface with a step-flow feature is obtained due to the enhanced re-evaporization rate and migration ability of Al adatoms.The samples grown at the higher temperature also show a higher crystalline quality than those grown at lower temperatures.展开更多
Al_(x)Ga_(1-x)/GaN heterostructures are investigated by magnetotransport experiments in tilted magnetic fields at low temperatures.The spin-split peaks of the Shubnikov-de Haas(SdH)oscillations are observed at high ma...Al_(x)Ga_(1-x)/GaN heterostructures are investigated by magnetotransport experiments in tilted magnetic fields at low temperatures.The spin-split peaks of the Shubnikov-de Haas(SdH)oscillations are observed at high magnetic fields,which are attributed to the Zeeman spin-splitting of the two-dimensional electron gas at the heterointerface.The exchange enhanced g*of the spin-splitting is investigated by measuring the positions of the pairs of spin-split SdH maxima.Moreover,it is found that g^(*)becomes smaller with the increasing tilt angle,which suggests the anisotropy of g^(*)is due to the strong polarization-induced electric field at the Al_(x)Ga_(1-x)N/GaN heterointerface.展开更多
基金by the National Natural Science Foundation of China under Grant Nos 11023003,60890193 and 60990313the Specialized Research Fund for the Doctoral Program of Higher Education in China.
文摘We investigate epitaxy of AlN layers on sapphire substrates by molecular beam epitaxy.It is found that an atomically flat surface can be obtained under Al-rich conditions at growth temperature of 780°C.However,the growth window to obtain an Al−droplet-free surface is too narrow to be well-controlled.However,the growth window can be greatly broadened by increasing the growth temperature up to 950°C,where an Al-droplet-free surface with a step-flow feature is obtained due to the enhanced re-evaporization rate and migration ability of Al adatoms.The samples grown at the higher temperature also show a higher crystalline quality than those grown at lower temperatures.
基金Supported by the National Natural Science Foundation of China under Grant Nos 60806042,10774001 and 60890193the Research Fund for the Doctoral Program of Higher Education in China(200800011021).
文摘Al_(x)Ga_(1-x)/GaN heterostructures are investigated by magnetotransport experiments in tilted magnetic fields at low temperatures.The spin-split peaks of the Shubnikov-de Haas(SdH)oscillations are observed at high magnetic fields,which are attributed to the Zeeman spin-splitting of the two-dimensional electron gas at the heterointerface.The exchange enhanced g*of the spin-splitting is investigated by measuring the positions of the pairs of spin-split SdH maxima.Moreover,it is found that g^(*)becomes smaller with the increasing tilt angle,which suggests the anisotropy of g^(*)is due to the strong polarization-induced electric field at the Al_(x)Ga_(1-x)N/GaN heterointerface.
