Study of subband electronic structure of Si delta-doped GaAs using magnetotransport measurements in tilted magnetic fields

Si delta-doped GaAs grown by metal organic vapor phase epitaxy (MOVPE) is characterized using magnetotransport measurements in tilted magnetic fields. Angular dependence of the longitudinal magnetoresistance (R(xx)) vs the magnetic field (B) traces in tilted magnetic fields is used to examine the existence of a quasi-two-dimensional electron gas. The subband electron densities (n(i)) are obtained applying fast Fourier transform (FFT) analysis to the R(xx) vs B trace and using mobility spectrum (MS) analysis of the magnetic field dependent Hall data. Our results show that (1) the subband electron densities remain roughly constant when the tilted magnetic field with an angle <30 degrees measured from the Si delta-doped plane normal is ramped up to 13 T; (2) FFT analysis of the R(xx) vs B trace and MS analysis of the magnetic field dependent Hall data both give the comparable results on subband electron densities of Si delta-doped GaAs with low delta-doping concentration, however, for Si delta-doped GaAs with very high delta-doping concentration, the occupation of the lowest subbands cannot be well resolved in the MS analysis; (3) the highest subband electron mobility reported to date of 45 282 cm(2)/s V is observed in Si delta-doped GaAs at 77 K in the dark; and (4) the subband electron densities of Si delta-doped GaAs grown by MOVPE at 700 degrees C are comparable to those grown by MBE at temperatures below 600 degrees C. A detailed study of magnetotransport properties of Si delta-doped GaAs in the parallel magnetic fields is then carried out to further confirm the subband electronic structures revealed by FFT and MS analysis. Our results are compared to theoretical calculation previously reported in literature. In addition,influence of different cap layer structures on subband electronic structures of Si delta-doped GaAs is observed and also discussed. (C) 1996 American Institute of Physics.