Subband electron properties of highly doped InAlAs/InGaAs metamorphic high-electron-mobility transistors on GaAs substrates

A Shubnikov-de Haas (SdH) oscillation measurement was performed on highly d oped InAlAs/InGaAs metamorphic high-electron-mobility transistors on GaAs s ubstrates at a temperature of 1.4 K. By analyzing the experimental data usi ng fast Fourier transform, the electron densities and mobilities of more th an one subband are obtained, and an obvious double-peak structure appears a t high magnetic field in the Fourier spectrum. In comparing the results of SdH measurements, Hall measurements, and theoretical calculation, we found that this double-peak structure arises from spin splitting of the first-exc ited subband (i=1). Very close mobilities of 5859 and 5827 cm(2)/V s are de duced from this double-peak structure. The sum of the carrier concentration of all the subbands in the quantum well is only 3.95x10(12) cm(-2) due to incomplete transfer of the electrons from the Si delta -doped layer to the well. (C) 2001 American Institute of Physics.