Electron mobility limits of twohyphen;dimensional electron gas in Nhyphen;AlGaAs/GaAs at low temperature

摘要

Using the warm electron coefficient, the electron mobility, mgr;inel, limited only by inelastic scattering was studied for twohyphen;dimensional electron gas confined to the GaAs side of an Nhyphen;AlGaAs/GaAs heterojunction. The warm electron coefficient bgr; was measured to be 0.1ndash;3times;10minus;3cm2/V2at the temperature 4.2ndash;30 K. The electron mobility mgr;inelis interpreted as the upper limit obtained in the condition free of ionized impurity scattering. The relation between bgr; and electron mobility mgr;inelfor twohyphen;dimensional electron gas is obtained as bgr;prop;mgr;inel, when ionized impurity scattering is predominant. Combining the theoretical relations and experimental results, the electron mobility limit of a twohyphen;dimensional electron gas at 4.2 K is found to be about 9.0times;106cm2/Vthinsp;sec at sheet electron concentration of 8times;1010cmminus;2. The exponent of its temperature dependence is minus;1.28.