Separation of bulk and surface electron transport in metamorphic InAs layers using quantitative mobility spectrum analysis

Abstract

Electron transport in low dislocation density, strain-relaxed InAs layers grown on metamorphic In Asy P1-y InP substrates by molecular beam epitaxy was characterized using quantitative mobility spectrum analysis (QMSA) of Hall effect measurements. QMSA applied to systematically varied metamorphic InAs samples reveals high bulk electron mobilities of ∼20 000 cm2 V s at 300 K at a Si doping concentration of 1× 1017 cm-3, simultaneously with a separate population of much slower electrons having an average mobility of ∼2400 cm2 V s due to parallel conduction within the InAs surface electron accumulation layer. Measurements made on higher doped samples reveal only a single electron population participating in transport due to lowered surface band bending that reduces surface accumulation of electrons in conjunction with the high conductivity of the high mobility metamorphic InAs bulk that overwhelms any remaining surface conductivity in the Hall effect measurements. © 2008 American Institute of Physics.