Photoreflectance of GaAs/SI-GaAs interface

Abstract

Photoreflectance spectra of doped molecular‐beam‐epitaxy GaAs films grown on semi‐insulating GaAs substrate, modulated by different pump beams, are studied. From the interference effect of two light beams reflected from different interfaces of a sample, the PR signals from the surface of the MBE film and that from the interface of film and substrate can be distinguished in the spectra. The behavior of the electric fields of the space charge region at the surface of GaAs and the interface of GaAs/SI‐GaAs is also investigated.

A comparison between contactless electroreflectance and photoreflectance spectra from n-doped GaAs on a semi-insulating GaAs substrate

“…The oscillatory feature is expected to be from the n-GaAs/SI-GaAs interface. It has been reported in the literature that for very high doping concentration only FKOs from the n-GaAs/SI-GaAs interface form the PR spectrum [12,14,15]. The disappearance of the PR signals from the surface for highly doped samples is due to spatial fluctuations of the SCR width, which is comparable to the mean atomic distance of the spatially random distribution of donors.…”

“…The doped-GaAs/SI-GaAs structure was studied by PR a decade ago [11][12][13][14][15]. The superposition of Franz−Keldysh oscillations (FKOs) from the doped GaAs surface and those from the doped GaAs/SI-GaAs interface was observed for thin samples [13][14][15].…”

“…The doped-GaAs/SI-GaAs structure was studied by PR a decade ago [11][12][13][14][15]. The superposition of Franz−Keldysh oscillations (FKOs) from the doped GaAs surface and those from the doped GaAs/SI-GaAs interface was observed for thin samples [13][14][15]. By using He−Ne and He−Cd lasers as the pump source respectively, the signals from the surface and the interface can be distinguished because of the different penetration depths of the two beams [13,14].…”

“…By proper selection of modulation frequency and phase shift, Alperovich et al [19] separated PR signals originating from various regions of a delta-doped GaAs structure. Signals from the surface and the interface can be distinguished for the n-GaAs/SI-GaAs structure by using He−Ne and He−Cd lasers as the pump source, respectively [13,14]. In this paper, a demonstration is shown that spectra from the surface or from the interface of the n-GaAs/SI-GaAs samples can be extracted individually by the combination of CER and PR.…”