High-Field Electron-Drift Velocity in n-Type Modulation-Doped GaAs0.96Bi0.04 Quantum Well Structure

The drift velocity (v(drift)) of electrons in an n-type modulation-doped GaAs0.96Bi0.04/Al0.15Ga0.85As quantum well (QW) structure is determined for electric fields (F) ranging from approximate to 0.4 to 3.58 kV cm(-1). The resulting v(drift) characteristic exhibited a linear increase and reached approximate to 6 x 10(6) cm s(-1) at low electric fields then almost saturated with increasing electric field. The electron drift mobility is determined as 2265 cm(2) Vs(-1) in the regime where the drift velocity is linear with respect to the electric field. The drift velocity saturates at approximate to 6.1 x 10(6) cm s(-1) at the electric fields between approximate to 2.7 and 3.4 kV cm(-1). Saturation of the drift velocity is attributed to the transfer of the electrons from the QW layer (GaAs0.96Bi0.04) with higher electron mobility to the barrier layer (Al0.15Ga0.85As) and satellite valley L-valley with lower electron mobility, which initiates cooling of electrons via phonon scattering in the sample.