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

The forward and reverse bias capacitance-voltage (C-V) and conductance-voltage (G/ω-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 Nss and series resistance Rs were strongly frequency dependent and decreased with increasing frequency. The effect of Rs 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 Rs to obtain real junction capacitance Cc and conductance Gc using the Nicollian and Goetzberger technique. The experimental C-V-f and G/ω-V-f characteristics of Si solar cells show fairly large frequency dispersion especially at low frequencies due to surface states Nss in equilibrium with the semiconductor. The distribution profile of Rs-V gives a peak in the accumulation region at high frequencies and disappears with decreasing frequencies. It can be concluded that the values of Rs are significant only in the downward curvature of the forward bias C-V characteristics and accumulation region, but the values of Nss are significant in both the inversion and depletion region.