Drift mobility of electrons in AlGaN/GaN MOSHFET

The dependence of electron mobility μn on sheet electron concentration in the channel has been measured for the first time in AlGaN/GaN MOSHFETs. The maximum value of μn ≃ 1400 cm2/Vs observed at ns = 7 × 1012 cm-2, is very close to the value derived from Hall measurements made on the same wafer. As the gate-bias voltage VG approaches the threshold value VT (VG → VT), the measured value of μn is ~100 cm2/Vs. This is very close to the value of electron mobility in a bulk GaN layer. The mechanism controlling the mobility against sheet-carrier density dependence is discussed.