Contactless determination of current–voltage characteristics and minority-carrier lifetimes in semiconductors from quasi-steady-state photoconductance data

Abstract

A simple method for implementing the steady-state photoconductance technique for determining the minority-carrier lifetime of semiconductor materials is presented. Using a contactless instrument, the photoconductance is measured in a quasi-steady-state mode during a long, slow varying light pulse. This permits the use of simple electronics and light sources. Despite its simplicity, the technique is capable of determining very low minority carrier lifetimes and is applicable to a wide range of semiconductor materials. In addition, by analyzing this quasi-steady-state photoconductance as a function of incident light intensity, implicit current-voltage characteristic curves can be obtained for noncontacted silicon wafers and solar cell precursors in an expedient manner.

Transition metal oxides as hole-selective contacts in silicon heterojunctions solar cells

“…In this sense, the contactless QuasiSteady-State Photoconductance (QSSPC) [38] Furthermore, by use of the methodology proposed by [39], we determined the emitter term of the saturation current density J 0e as a function of the effective lifetime τ eff : (1) where q is the elementary charge, n i the intrinsic carrier concentration in silicon, W the wafer thickness, N D the wafer doping concentration and Δn the minority excess carrier density (under high injection conditions). The term 1/τ bulk can be neglected owing to the long bulk lifetime of high quality wafers, whereas the surface recombination velocity S rear for the laserfired a-Si:H/SiC:H stack was estimated at ~50 cm/s [26].…”

Bulk and surface passivation of silicon solar cells accomplished by silicon nitride deposited on industrial scale by microwave PECVD

“…Prior to both-side deposition of SiN x :H, the wafers obtained an RCA clean. The surface recombination velocity was determined using the quasi-steady-state photoconductance (QSSPC) 56 method. Thermal stability of the films was determined by repeating the QSSPC measurements after a thermal anneal of the wafers.…”

Light-induced performance increase of silicon heterojunction solar cells

“…To track the electronic changes at the a-Si:H/c-Si interface, excess carrier lifetimes, s eff , of the wafers were measured with the photo-conductance method in transient mode (WCT-120, Sinton Instruments), which complies with SEMI standard PV-13. 36 The finished SHJ cells were characterized by current-voltage measurements on a 1-sun solar simulator under Air Mass 1.5 global illumination. The measurement errors expected to be less than 60.6% relative.…”