Simulation and Lock-In Phase Analysis in Photoreflectance Modulation Spectroscopy of Gaas And Photoreflectance Investigations of The Heterojunction Structure Al x ga 1–X as(N + )/Gaas(P − )/Gaas(P + )

The photoreflectance (PR) is a sensitive optical method for examining the surface and interface properties of semiconductors . The important substrates that are available for light emitting technology are GaAs and InP. In this report, we simulate PR Spectra of GaAs in two cases: single-layer model (surface field is homogeneous in depth d), and multi—layer model (surface field decreases with depth d). By the multi-layer model, we received simulation results that are very similar to the experimental results. Important semiconductor materials exploited in optoelectronics are the AlxGa1–xAs alloys which are lattice matched very well to GaAs substrates. With the multi-layer model we simulated the PR spectra of the heterojunction structure AlxGa1–xAs / GaAs / GaAs (x = 0.05) for heterojunction— LEDs. The two-channel (X,Y) lock-in phase analysis is one of the most powerful methods for studying multi-component PR spectra . In this report, we set up the phase diagram in three-dimensions: X(E), Y (E) and E (energy of photon) coordinates. The 3-D phase diagrams indicate the number of the spectral components in a multi-component PR spectra (Franz-Keldysh oscillation-FKO; Exciton or Low-energy oscillation inter-ference-LEOI).