The impact of interface electric field on the photoreflectance of semiconductor multilayers revisited with the heterostructures of InGaAs/InP

Abstract In the photoreflectance (PR) of semiconductor heterostructure layers, modulated signals may arise from the modulation of both surface and interface electric potentials. Effectively distinguishing these different sources is necessary to unravel the interfacial electronic properties. However, understanding this aspect remains a challenge for the PR technique. This work revisits the topic through PR experiments on the lattice-matched single heterostructure (SH) of InGaAs/InP and the double heterostructure (DH) of InP/InGaAs/InP, which were grown by molecular beam epitaxy. We examine the modulation effect at two laser wavelengths, 532 nm and 1064 nm, for which the 1064 nm laser only generates modulation of the interface electric field for the DH sample. The confined energy levels of a two-dimensional electron gas at the interface are disclosed under the modulation of either laser. However, the 1064 nm laser is beneficial to probe the interface electronic structure of the deeply buried interface, avoiding the inhibition from the absorption of the InP layer on top. Furthermore, the results of the DH sample with the modulation of the 1064 nm laser demonstrate the other virtue of the interface modulation: it allows probing of the wide bandgap semiconductor, despite the laser having lower energy than that demanded to excite the band-to-band transition of the wide energy bandgap.