Frequency and voltage dependent surface states and series resistance of novel Si solar cells

Abstract

The forward and reverse bias capacitance-voltage (C-V) and conductance-voltage (G/omega-V) characteristics of novel Si solar cells are studied over a wide frequency and temperature range of 10-500 kHz and 79-400 K, respectively. Both the density of interface states N-ss, and series resistance R(s)were strongly frequency dependent and decreased with increasing frequency. The effect of R-s on the capacitance (C) and conductance (G) are found noticable at high frequencies. Therefore, the high frequencies capacitance and conductance are measured between -6 and 6 V and corrected for the effect of series resistance R-s to obtain real junction capacitance C-c and conductance G(c) using the Nicollian and Goetzberger technique. The experimental C-V-f and G/co-V-fcharacteristics of Si solar cells show fairly large frequency dispersion especially at low frequencies due to surface states N-ss in equilibrium with the semiconductor. The distribution profile of R-s-V gives a peak in the accumulation region at high frequencies and disappears with decreasing frequencies. It can be concluded that the values of R-s are significant only in the downward curvature of the forward bias C-V characteristics and accumulation region, but the values of N-ss are significant in both the inversion and depletion region. (c) 2006 Elsevier B.V. All rights reserved.