Correlation of polycrystalline Cu(In,Ga)Se{sub 2} device efficiency with homojunction depth and interfacial structure: X-ray photoemission and positron annihilation spectroscopic characterization
- National Renewable Energy Lab., Golden, CO (United States)
- Brookhaven National Lab., Upton, NY (United States)
Angled-resolved high resolution photoemission measurements on valence band electronic structure and Cu 2p, In 3d, Ga 2p, and Se 3d core lines were used to evaluate surface and near-surface chemistry of CuInSe{sub 2} and Cu(In,Ga)Se{sub 2} device grade thin films. XPS compositional depth profiles were also acquired from the near-surface region, and bonding of the Cu, In, Ga, and Se was determined as a function of depth. A Cu-poor region was found, indicating CuIn{sub 5}Se{sub 8} or a CuIn{sub 3}Se{sub 5}-In{sub 2}Se{sub 3} mixture. Correlation between the depth of the Cu-poor region/bulk interface and device efficiency showed that the depth was 115 {angstrom} for a 16.4% CIGS device, 240 {angstrom} for a 15.0% CIGS, and 300 {angstrom} for 14.0% CIGS, with similar trends for CIS films. The surface region is n-type, the bulk is p-type, with a 0.5 eV valence band offset. Depth of homojunction may be the determining factor in device performance. Positron annihilation spectroscopy gave similarly illuminating results.
- Research Organization:
- Brookhaven National Lab., Upton, NY (United States)
- Sponsoring Organization:
- USDOE, Washington, DC (United States)
- DOE Contract Number:
- AC02-76CH00016
- OSTI ID:
- 10159076
- Report Number(s):
- BNL-60422; CONF-941203-1; ON: DE94013543
- Resource Relation:
- Conference: 1. world conference on photovoltaic energy conversion,Waikoloa, HI (United States),5-9 Dec 1994; Other Information: PBD: [1994]
- Country of Publication:
- United States
- Language:
- English
Similar Records
Spectroscopic Evidence for a Surface Layer in CuInSe2:Cu Deficiency
Determination of composition and phase depth-profiles in multilayer and gradient solid solution photovoltaic films using grazing incidence x-ray diffraction