Ultrafast Carrier Dynamics in LT-GaAs, Doped by δ-si

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 lops) and high carrier mobility (10-100 cm(2)/(V * s)). Due to all carrier properties of LT-GaAs, we chose 2 samples of LT-GaAs with s-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 s-Si doping, we use model for transient reflectivity Ortiz [1]. In the model, four parameters were used: Na acceptor concentration and N-dd - deep donor concentration, beta(c) - electron capture coefficient, beta(v), hole capture coefficient. These parameters give us full information about electron-hole system and can be useful for Thz devices.