Drift mobility of electrons in AlGaN/GaN MOSHFET

The dependence of electron mobility mu (n) on sheet electron concentration in the channel has been measured for the first time in AlGaN/GaN MOSHFETs. The maximum value of mu (n) similar or equal to 1400cm(2)/Vs observed at n(s) = 7 x 10(12)cm(-2), is very close to the value derived from Hall measurements made on the same wafer. As the gate-bias voltage V-G approaches the threshold value V-T (V-G --> V-T), the measured value of mu (n) is similar to 100 cm(2)/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.