Electron drift velocity measurement in compositionally graded Al<i>x</i>Ga1−<i>x</i>As by time-resolved optical picosecond reflectivity

Abstract

We have measured for the first time the velocity of minority-carrier electrons in a heavily doped (p = 2×1018 cm−3) molecular beam epitaxy grown compositionally graded (0.12 eV/μm) AlxGa1−x As layer. The drift velocity is determined to be ve = 2.3×106 cm/s in a quasi-electric field of 1.2 kV/cm.