Electrical properties of CdS/Cu(In,Ga)Se2 interface

We present an experimental method to measure and extract the interface density of states and fixed charge at the CdS/Cu(In,Ga)Se-2 (CIGS) interface using the capacitance-voltage technique applied to a metal-insulator-semiconductor structure. The density of interface states is on the order of 10(10) to 10(13)cm(-2)eV(-1). The effective fixed charge at the interface is (7.8 +/- 0.3) x 10(11) cm(-2) and due to positive charges. These electrical properties make the CdS/CIGS interface well passivated and to some extent resemble the SiNx/p-Si interface. We also measure the inversion strength (i.e., Fermi level at the interface) and capture cross-section of interface states from admittance spectroscopy. Inputting the above extracted parameters into the extended Shockley-Read-Hall recombination formulation by Eades and Swanson [J. Appl. Phys. 58, 4267 (1985)], we calculate the surface recombination velocity of mid-to-high 10(3) cm.s(-1), which agrees reasonably with temperature-intensity dependent recombination analysis. (c) 2018 The Japan Society of Applied Physics