Role of deep levels and interface states in the capacitance characteristics of all‐sputtered CuInSe2/CdS solar cell heterojunctions

Abstract

All‐sputtered CuInSe2/CdS solar cellheterojunctions have been analyzed by means of capacitance‐frequency (C‐F) and capacitance‐bias voltage (C‐V) measurements. Depending on the CuInSe2 layer composition, two kinds of heterojunctions were analyzed: type 1 heterojunctions (based on stoichiometric or slightly In‐rich CuInSe2 layers) and type 2 heterojunctions (based on Cu‐rich CuInSe2 layers). In type 1 heterojunctions, a 80‐meV donor level has been found. Densities of interface states in the range 101 0–101 1 cm2 eV− 1 (type 1) and in the range 101 2–101 3 cm− 2 eV− 1 (type 2) have been deduced. On the other hand, doping concentrations of 1.6×101 6 cm− 3 for stoichiometric CuInSe2 (type 1 heterojunction) and 8×101 7 cm− 3 for the CdS (type 2 heterojunction) have been deduced from C‐Vmeasurements.