Metal insulator transition in n-BGaInAs

Isovalent boron is expected to form highly localized states within the conduction band of the GaInAs host which according to most present experimental findings only weakly influences the structure of the extended host states. Here we present magnetotransport (MR) measurements on three n-type BGaInAs samples doped with silicon which vary in free carrier concentration n from 4.0 x 1016 cm-3 to 7.2 x 1017 cm-3. The three samples differ strongly in their resistivity behaviour. Whereas the sample with the highest n shows metallic behaviour, the transport behaviour of the sample with the lowest n is dominated by hopping transport. The latter is manifested by an exponential increase of the resistivity in the magnetic field. The experimental results are interpreted as a metal insulator transition (MIT). The MIT is found at unexpectedly high carrier concentration compared to GaAs which is attributed to increased alloy disorder in the quarternary alloy mainly due to the localized boron states. (copyright 2008 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)