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InP Solar Cell Development on Inexpensive Si Substrates. Phase 1.

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Final rept.,

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Indium phosphide InP solar cells were made on silicon Si wafers to take advantage of both the radiation-hardness properties of the InP solar cell and the light weight and cost savings of Si wafers compared to either InP or germanium Ge wafers. Calculations are presented which show that in very high radiation environments e.g. van Allen proton belts, these cells can provide over twice as much EOL power density than GaAsGe or Si cells. Both PN and NP cell architectures were examined since each may have advantages depending on the radiation environment. N-on-P NP InP-on-Si InPSi 2 cm by 4 cm cells were made with one-sun air mass zero AM0 beginning-of-life BOL efficiencies up to 12.5. The average efficiency of fifteen 2 cm by 2 cm InPSi cells on 16 mil Si wafers sent to NASA-Lewis for independent efficiency verification was 12.3 best cell 12.6. Data are presented comparing 1 MeV electron and 3.9 MeV alpha particle irradiation showing relatively little cell power output degradation out to a very high fluence less than 20 after a fluence of about 4 x 10exp 16 1 MeV electrons sq cm, about 40X the standard fluence. NP cells have better overall performance than PN cells up to equivalent 1 MeV electron fluences of approx. 3 x 10exp 16sq cm, or about 30X the current standard of 10exp 15 1 MeV electronssq cm. PN cells had BOL efficiencies up to 9.9, due to a lower photocurrent than NP cells since a thin emitter is hard to obtain with high diffisivity zinc P-type dopant. However, for equivalent fluences in excess of 3 x 10exp 16 1 MeV electrons sq cm, some proton irradiation data indicates that the PN InPSi cells may have more power output in this regime than their NP counterparts. p6

Subject Categories:

  • Electric Power Production and Distribution
  • Inorganic Chemistry
  • Radiation and Nuclear Chemistry
  • Electrical and Electronic Equipment
  • Electricity and Magnetism

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