Charge conduction mechanisms and photovoltaic properties of n-(Ga₂S₃-Ga₂Se₃)/p-Si heterojunctions

Physics Department, Faculty of Education, Ain Shams University, Roxy square, 11757 Cairo, Egypt

Corresponding author: elrahman99@hotmail.com

Received: 9 August 2006
Revised: 14 October 2006
Accepted: 31 October 2006
Published online: 17 January 2007

Abstract

Electrical and photoelectrical measurements are made at different temperatures on heterojunction photovoltaic cells fabricated by vacuum deposition of n-(Ga₂Se₃-Ga₂S₃) thin films onto p-Si single crystals. A complete study of the current density as a function of voltage and temperature is carried out in order to gain fundamental information on trap depth, trap distribution and position of the Fermi level. At high forward bias, the results are consistent with space-charge-limited conduction due to an exponentially decreasing distribution of traps. At low voltages, the dark current density in the forward direction varies exponentially with voltage. The devices exhibit strong photovoltaic characteristics with an open-circuit voltage of 0.70 V, a short-circuit current density of 9.42 mA cm⁻² and a power conversion efficiency of 5.20%. These parameters have been estimated at room temperature and under light illumination provided by a halogen lamp with an input power density of 50 mW cm⁻².