Final Report: Preparation and Evaluation of N-Type CdSeTe and CdTe as an Absorber in Thin Film PV
The primary objective of this project was to demonstrate n-type CdTe and CdSeTe films prepared by in-situ doping methods using pre-doped source material. Our goal was to achieve electron density (>1017 cm-3) and lifetime (>10 ns) in n-type CdTe and CdSeTe films. The focus was on indium as the dopant, as it is suitable for incorporation during melt growth of CdTe. It was thought that indium doped bulk crystals might exhibit self compensation and high resistivity, so post-growth annealing studies were planned to manipulate crystal stoichiometry, defects and electrical activity. Single crystals of CdTe:In and CdSe0.4Te0.6:In, with target In concentration 1019 cm-3, were grown by the vertical Bridgman crystal growth method at Washington State University (WSU). Incorporation of the intended In into the crystals was ~25%-30%, (2.5-3) ×1018 cm-3, according to glow discharge mass spectrometry (GDMS). Carrier concentration in CdTe:In crystals were very low until after a Cd anneal, at which point the concentration reached 8 ×1017 cm-3 (~27% activation) according to Hall effect and time resolved photoluminescence (TRPL). CdSeTe:In, on the other hand, had ~100% carrier activation with no post-growth treatments, resulting in ~3×1018 cm-3 carriers with a lifetime of 1.5 ns, near the radiative limit for this material.
- Research Organization:
- Washington State Univ., Pullman, WA (United States)
- Sponsoring Organization:
- USDOE Office of Energy Efficiency and Renewable Energy (EERE), Renewable Power Office. Solar Energy Technologies Office
- Contributing Organization:
- National Renewable Energy Laboratory
- DOE Contract Number:
- EE0008548
- OSTI ID:
- 1769405
- Report Number(s):
- WSU1920-8548-0
- Country of Publication:
- United States
- Language:
- English
Approach to Defect-Free Lifetime and High Electron Density in CdTe
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journal | April 2019 |
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