Intrinsic Broadening of the Mobility Spectrum of Bulk N-Type GaAs

Modern devices consisting of multiple semiconductor layers often result in the population of numerous distinct carrier species. Conventional Hall measurements at a single-magnetic-field strength provide only a weighted average of the electron mobility and carrier concentration of a semiconductor structure and, therefore, are of limited use for the extraction of carrier transport information. In recent years, mobility spectrum analysis techniques, which have been developed to extract a mobility spectrum from magnetic field-dependent conductivity-tensor measurements, have been applied in the analysis of carrier conductivity mechanisms of numerous semiconductor structures and devices. Currently there is a severe lack of reported studies on theoretical calculations of the mobility distribution of semiconductor structures or devices. In addition, the majority of reports on experimental mobility spectrum analysis are of complex, multi layered structures such as type-II superlattices, and the interpretation of the mobility spectra has been difficult. Therefore, a good understanding of the mobility spectrum has yet to be developed. For example, it is often assumed that distinct peaks of a mobility spectrum result from fundamentally different conduction mechanisms such as the bulk and surface conduction of narrow-bandgap semiconductors. In this article, we present calculations of the electron mobility distribution of bulk GaAs, which predict the existence of multiple mobility spectrum peaks that result from electron conductivity in the Γ conduction band. This report serves as an important and simple test case upon which experimentally measured mobility spectra can be compared. It also presents insight into the general nature of electron mobility distributions.