Electron mobility limits of two-dimensional electron gas in N-AlGaAs/GaAs at low temperature

Using the warm electron coefficient, the electron mobility, μinel, limited only by inelastic scattering was studied for two-dimensional electron gas confined to the GaAs side of an N-AlGaAs/GaAs heterojunction. The warm electron coefficient β was measured to be 0.1–3×10−3 cm2/V2 at the temperature 4.2–30 K. The electron mobility μinel is interpreted as the upper limit obtained in the condition free of ionized impurity scattering. The relation between β and electron mobility μinel for two-dimensional electron gas is obtained as β∝μinel, when ionized impurity scattering is predominant. Combining the theoretical relations and experimental results, the electron mobility limit of a two-dimensional electron gas at 4.2 K is found to be about 9.0×106 cm2/V sec at sheet electron concentration of 8×1010 cm−2. The exponent of its temperature dependence is −1.28.