Background subtraction in Fourier-domain mobility spectrum analysis for resolving low-mobility carriers

Narrow gap semiconductors and superlattices relevant to optoelectronics often host multiple conducting species, such as electrons and holes, requiring a mobility spectral analysis (MSA) method to separate contributions to the conductivity. Building on the Fourier-domain MSA (FMSA) method proposed previously by the authors, we introduce a background subtraction step prior to FMSA to more accurately extract the spectral mobilities below what is normally considered the low mobility threshold μth = 1/Bmax, where Bmax is the maximum magnetic field of the experimental data under analysis. This preliminary step subtracts a linear background from the magnetotransport data and enables a more accurate fit in the low mobility range by several orders of magnitude. Background subtraction extends the useful low-mobility limit by a factor of 5 to μmin = 1/5Bmax, and can be easily applied in other MSA techniques where low mobilities are of interest.