FT-PL analysis of CIGS/CdS/Zno interfaces

High-quality copper indium gallium diselenide (CIGS) films were subjected to a variety of surface treatments attendant to and including deposition of CdS and/or ZnO junctions or buffer layers. The resulting devices were analyzed at 87 K using Fourier transform photoluminescence (FT-PL) spectroscopy as part of a battery of analytical procedures, including surface analysis, ellipsometry, and I–V measurements, designed to elucidate the influences of the several interfaces on device performance. Our FT-PL system was upgraded with a miniature Joule-Thomson cryostat and a helium-neon laser excitation source to enable collection of highly-resolved, continuous PL spectra from 950–1750 nm. The PL intensity enhancements measured with the upgraded FT-PL system for devices fabricated using chemical bath deposition (CBD) of CdS, with or without a ZnO electrode, are much greater than for devices incorporating physical vapor deposited (PVD) CdS or ZnO/CIGS interfaces. Exposure of the CIGS films to components of the CBD ...