Intrinsic broadening of the mobility spectrum of bulk n-type GaAs

Historically, the mobility of semiconductor charge carriers is treated as a single-valued function of temperature and other parameters such as the doping concentration. Such a description has been adequate for electronic devices with behaviors that are dominated by bulk carrier transport. Treating carrier mobility as a single valued function is consistent with conventional Hall measurements which are performed at a single value of magnetic field strength and provide only a weighted average of the electron mobility and carrier concentration of a semiconductor structure. Modern electronic devices consisting of numerous semiconductor layers often result in the population of numerous distinct carrier species, therefore, treating carrier mobility as a single valued function of temperature and other semiconductor device parameters such as carrier concentration can be a completely inadequate description. Mobility spectrum analysis is an experimental technique based on magnetic field-dependent conductivity-tensor measurements for the extraction of a mobility distribution. Mobility spectrum analysis has been applied to the study of the carrier conductivity mechanisms of numerous semiconductor structures and devices. However, 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 mobility spectra has yet to be developed. We present calculations of the electron mobility distribution of bulk GaAs which predicts the existence of multiple mobility distribution peaks resulting 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 and presents insight into the general nature of electron mobility distributions.