InP Solar Cell Development on Inexpensive Si Substrates. Phase 1.
Abstract
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 GaAs/Ge or Si cells. Both P/N and N/P cell architectures were examined since each may have advantages depending on the radiation environment. N-on-P (N/P) InP-on-Si (InP/Si) 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) InP/Si 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 10(exp 16) 1 MeV electrons/ sq cm, about 40X the 'standard' fluence). N/P cells have better overall performance than P/N cells up to equivalent 1 MeV electron fluences of approx. 3 x 10(exp 16)/sq cm, or about 30X the current "standard" of 10(exp 15) 1 MeV electrons/sq cm. P/N cells had BOL efficiencies up to 9.9%, due to a lower photocurrent than N/P 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 10(exp 16) 1 MeV electrons/ sq cm, some proton irradiation data indicates that the P/N InP/Si cells may have more power output in this regime than their N/P counterparts. p6
Document Details
- Document Type
- Technical Report
- Publication Date
- Oct 01, 1995
- Accession Number
- ADA310745
Entities
People
- Steven J. Wojtczuk