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Proton irradiation of CdTe thin film photovoltaics deposited on cerium‐doped space glass
Author(s) -
Lamb Dan A.,
Underwood Craig I.,
Barrioz Vincent,
Gwilliam Russell,
Hall James,
Baker Mark A.,
Irvine Stuart J.C.
Publication year - 2017
Publication title -
progress in photovoltaics: research and applications
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.286
H-Index - 131
eISSN - 1099-159X
pISSN - 1062-7995
DOI - 10.1002/pip.2923
Subject(s) - materials science , fluence , photovoltaics , cadmium telluride photovoltaics , solar cell , irradiation , quantum efficiency , optoelectronics , acceptor , doping , thin film , analytical chemistry (journal) , photovoltaic system , nanotechnology , chemistry , electrical engineering , physics , condensed matter physics , chromatography , nuclear physics , engineering
Space photovoltaics is dominated by multi‐junction (III‐V) technology. However, emerging applications will require solar arrays with high specific power (kW/kg), flexibility in stowage and deployment, and a significantly lower cost than the current III‐V technology offers. This research demonstrates direct deposition of thin film CdTe onto the radiation‐hard cover glass that is normally laminated to any solar cell deployed in space. Four CdTe samples, with 9 defined contact device areas of 0.25 cm 2 , were irradiated with protons of 0.5‐MeV energy and varying fluences. At the lowest fluence, 1 × 10 12 cm −2 , the relative efficiency of the solar cells was 95%. Increasing the proton fluence to 1 × 10 13 cm −2 and then 1 × 10 14 cm −2 decreased the solar cell efficiency to 82% and 4%, respectively. At the fluence of 1 × 10 13 cm −2 , carrier concentration was reduced by an order of magnitude. Solar Cell Capacitance Simulator (SCAPS) modelling obtained a good fit from a reduction in shallow acceptor concentration with no change in the deep trap defect concentration. The more highly irradiated devices resulted in a buried junction characteristic of the external quantum efficiency, indicating further deterioration of the acceptor doping. This is explained by compensation from interstitial H + formed by the proton absorption. An anneal of the 1 × 10 14 cm −2 fluence devices gave an efficiency increase from 4% to 73% of the pre‐irradiated levels, indicating that the compensation was reversible. CdTe with its rapid recovery through annealing demonstrates a radiation hardness to protons that is far superior to conventional multi‐junction III‐V solar cells.