Equivalent Circuit Model to Reach Complicated Surface Photovoltage Transient Shapes in ZnO Thin Films

Abstract

The dynamics of photoexcited carriers in magnetron sputtered ZnO films is characterized employing time-domain impedance analysis, which is based on the measurements of the surface photovoltage (SPV) transients. The studies focus on observing the damage after the implantation of Nd + ions in ZnO layers and a subsequent anneal. We observed the positive and negative components of the measured SPV transient and develop equivalent circuits of the structure involving multiple series of parallel resistance (R), capacitance (C), and inductance (L) elements, and derive a simple fitting procedure which allows to reproduce accurately the measured SPV transient. The relationship between these RCL elements and a rough physical picture of the charge transport phenomena in the interface regions of the structure is envisaged. This approach is conceptually useful for characterizing interfaces in semiconductor structures and devices.