Non-destructive photoreflectance characterization of sheet carrier density in InAlAs/InGaAs HEMTs

Using room-temperature-photoreflectance (PR), we have succeeded in characterizing InGaAs channel layers of InAlAs/InGaAs high electron mobility transistors (HEMTs). The few peaks are observed in the PR spectra correspond to the transitions between ground- and excited subbands of 2DEG and 2DHG in the channel layer. The peak shift to the higher energy side is monitored with increasing N_s. Thus, PR spectroscopy is quite useful for the non-destructive characterization of N_s at room temperature