The Capacitance Modulated by the Convolution between Optical and Electrical Signals Using the GaAsN/GaAs Quantum Well

Abstract

probed using a small signal analysis method. In general, a small alternating voltage is applied to the sample and the current is produced with a delayed phase. The impedance can be obtained using the phase delay. The current contains two components: conductive in the real part, and a capacitive current in quadrature in the imaginary part. These two components will couple to each other, and compose a small transient current in response to the small applied alternating voltage [12]. However, if a light pulse is applied to the device, a transient photo-current will be induced. The additional photo-current will also have two components: a conductive and capacitive current, which will also couple with the transient current induced by the small alternating voltage. The process becomes complicated when the light pulse illuminates the device. In order to simplify the scenario, we chose a QW sample with a large conductive current yet small capacitive current. In this case we only have to analyze the optically induced conductive current convolution with the transient current induced by the electrical source. We will begin with the impedance method, since the impedance of the ω-function can be Fourier transformed from the transient current of a t-function [12].