DETERMINATION OF ELECTRON RECOMBINATION PARAMETERS IN GAAS/ALGAAS QUANTUM-WELLS BY IMPEDANCE SPECTROSCOPY

We show that the capture process between a three-dimensional (3D) gas and a two-dimensional quantum well are unambiguously characterized by impedance spectroscopy. The contact layer of an asymmetrical semiconductor-insulator-semiconductor diode provides the 3D gas to the conduction band of an AlGaAs barrier which interacts near thermal equilibrium with a GaAs quantum well (QW). This approach is validated by an excellent agreement between experimental results and theoretical expectations regarding the influence of electric field and temperature. We show that the natural quantity which describes this recombination is the recombination velocity in the QW, which is found to be almost-equal-to 8 X 10(4) cm/s for a 60 angstrom GaAs/Al0.22Ga0.78As quantum well at 100 K for an electric field of 3 kV/cm, which corresponds to a capture probability of 0.013. Results indicate a decrease of the recombination velocity in the quantum well with an increasing applied electric field.