Raman Spectroscopic Studies of ZnSe/GaAs Interfaces
نویسنده
چکیده
ZnSe/semi-insulating GaAs interfaces have been studied by observing Photogenerated plasmon – LO (PPL) coupled modes by non-resonant microRaman spectroscopy. The effect of the carriers generated by the focused laser beam was investigated for a series of different thicknesses of ZnSe epitaxial layers. The PPL mode in GaAs is observed in micro-Raman spectra for all samples, but with different magnitude. The plasma is believed to be electron gas as a result of the negative nature of the interfacial region that contains predominantly hole traps. The free carriers' concentration is estimated to be > 10 18 cm -3 and their life time to be ≈ 0.1 ns. This relatively long lifetime suggests that the ZnSe/GaAs interface has to be of high structural quality leading to low recombination velocity. ZnSe/GaAs heterostructures of less crystalline quality (as determined by resonant Raman measurements) shows the effect of photogenerated carriers only to lesser extent.
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