Photoreflectance Characterization of a Channel Layer of InAlAs/InGaAs High Electron Mobility Transistor Wafers

Abstract

Using room-temperature (RT) -photoreflectance (PR), we have succeeded in characterizing InGaAs channel layers of InAlAs/InGaAs high electron mobility transistors (HEMTs). The relationship between PR spectra and sheet carrier density (Ns) is discussed. The valleys observed in the PR spectra correspond to the transitions between the quantized levels in the valence and conduction bands. A valley shift to the lower energy side is observed with increasing Ns, which corresponds to the shift of the intersubband energies. The calculation of the intersubband energies supports the results of the PR measurements. PR spectroscopy is quite promising for the non-destructive characterization of Ns of InAlAs/InGaAs HEMTs at RT.