Ultrafast carrier dynamics in LT-GaAs, doped by Æ-si

Abstract

Low temperature grown GaAs (LT-GaAs) became one of the most promising materials for ultrafast optical and THz devices. As well as known, LT-GaAs has major properties: low carrier lifetime (1–10ps) and high carrier mobility (10–100cm2/(V ∗ s)). Due to all carrier properties of LT-GaAs, we chose 2 samples of LT-GaAs with δ-Si at substrates with different crystal orientations ([100] and [111]). These samples were chosen to see the influence of crystal orientation on carrier dynamics. As a method for investigation of ultrafast carrier dynamics, we chose “pump-probe” transient reflectivity methodic at room temperature. To understand ultrafast processes in LT-GaAs with ?-Si doping, we use model for transient reflectivity Ortiz [1]. In the model, four parameters were used: N a — acceptor concentration and N dd — deep donor concentration, β c — electron capture coefficient, β v hole capture coefficient. These parameters give us full information about electron-hole system and can be useful for Thz devices.