Enhancement of the Hall mobility in undoped GaAs with low carrier concentration by light excitation

Abstract

We report the investigation of the steady-state Hall mobility behavior upon extrinsic light excitation in n-type liquid-encapsulated Czochralski GaAs crystals. The carrier concentration of the samples measured in the dark ranged from 108 to 3×1011 cm−3. The Hall mobility demonstrated a pronounced minimum in the concentration region 109–1011 cm−3. In samples of this region a significant increase of the Hall mobility from ⩾1460 to 6300–7800 cm2 V s could be induced by light, in some cases without an increase of the measured carrier concentration. Such behavior was explained by reduction of the mesoscopic nonuniformities related to the cellular structure of dislocations by the carriers generated from defect levels in the band gap.