Electroreflectance bias-wavelength mapping of the modulation Si δ-doped pseudomorphic GaAs/InGaAs/AlGaAs structure

The electroreflectance bias-wavelength mapping is proposed as a tool for characterization of low-dimensional structures. The results of room-temperature measurements on modulation Si δ-doped pseudomorphic GaAs/InGaAs/AlGaAs heterostructure with high mobility two-dimensional electron gas are presented. Franz–Keldysh oscillations (FKO) in GaAs layer are analyzed using fast Fourier transform (FFT) mapping in order to find an electric field in the GaAs layer. Two frequencies of FKO are identified in the FFT spectra, which are attributed to transitions involving heavy and light holes. Two transitions within the InGaAs quantum well are found at zero bias and an additional transition becomes apparent in reversely biased structure. Spectral features due to spin-orbit split holes in GaAs, back AlGaAs barrier, and AlGaAs/GaAs superlattice are also identified.