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.
Compounds and heterostructures in optical devices often host multiple carrier species that contribute simultaneously to the
total electrical conduction, making it difficult to distinguish the characteristics of each type. Here a Fourier-domain
Mobility Spectrum Analysis (FMSA)1 is introduced to sort the conductivity contributions of different carrier species from
magnetotransport measurements. Using simulated magnetotransport data from 0 to 15 T of a simple initial trial spectrum,
FMSA iteratively adjusts the spectral points in either the mobility domain or its Fourier reciprocal space to fit a mobility
range spanning over three orders of magnitude (μ = 670 ~ 1,000,000 cm2/V·s). With its alternating local and global
adjustments, FMSA is able to recover the mobility distribution of test data, as verified in convergence plots of the total
error as a function of iteration number. This technique resolves the mobility spectra as well or better than competing MSA
techniques with a simple and elegant algorithm, while precisely resolving the smoothness and width of mobility peaks
without artificial broadening.