CdSxTe1-x Alloying in CdS/CdTe Solar Cells

Conference · Sun May 01 00:00:00 EDT 2011

DOI:https://doi.org/10.1557/opl.2011.1151· OSTI ID:1018080

Duenow, J N; Dhere, R G; Moutinho, H R; To, B; Pankow, J W; Kuciauskas, D; Gessert, T A

A CdSxTe1-x layer forms by interdiffusion of CdS and CdTe during the fabrication of thin-film CdTe photovoltaic (PV) devices. The CdSxTe1-x layer is thought to be important because it relieves strain at the CdS/CdTe interface that would otherwise exist due to the 10% lattice mismatch between these two materials. Our previous work [1] has indicated that the electrical junction is located in thisinterdiffused CdSxTe1-x region. Further understanding, however, is essential to predict the role of this CdSxTe1-x layer in the operation of CdS/CdTe devices. In this study, CdSxTe1-x alloy films were deposited by RF magnetron sputtering and co-evaporation from CdTe and CdS sources. Both radio-frequency-magnetron-sputtered and co-evaporated CdSxTe1-x films of lower S content (x<0.3) have a cubiczincblende (ZB) structure akin to CdTe, while those of higher S content have a hexagonal wurtzite (WZ) structure like that of CdS. Films become less preferentially oriented as a result of a CdCl2 heat treatment at~400 degrees C for 5 min. Films sputtered in a 1% O2/Ar ambient are amorphous as deposited, but show CdTe ZB, CdS WZ, and CdTe oxide phases after a CdCl2 heat treatment (HT). Filmssputtered in O2 partial pressure have a much wider bandgap (BG) than expected. This may be explained by nanocrystalline size effects seen previously [2] for sputtered oxygenated CdS (CdS:O) films.

• Research Organization: National Renewable Energy Lab. (NREL), Golden, CO (United States)
• Sponsoring Organization: USDOE Office of Energy Efficiency and Renewable Energy (EERE), Renewable Power Office. Solar Energy Technologies Office
• DOE Contract Number: AC36-08GO28308
• OSTI ID: 1018080
• Report Number(s): NREL/CP-5200-50156; TRN: US201113%%533
• Resource Relation: Journal Volume: 1324; Conference: Presented at the 2011 Materials Research Society Spring Meeting, 25-29 April 2011, San Francisco, California
• Country of Publication: United States
• Language: English

Related Subjects

14 SOLAR ENERGY
36 MATERIALS SCIENCE
ALLOYS
FABRICATION
HEAT TREATMENTS
MAGNETRONS
OXIDES
PARTIAL PRESSURE
SOLAR CELLS
SPUTTERING
STRAINS
CdS
CdTe
solar cells
photovoltaics
thin films
PV