InP Solar Cell Development on Inexpensive Silicon Substrates
Abstract
Optimize Emitter/Base Dopants - In this section, we describe some of the differences between Spire's previous N-on-P technology and the P-on-N technology being developed for this program. Results of a 17% P/N InP cell, the best made to date are also summarized. The main reason for the change to a P/N cell is that P/N heteroepitaxial InP cells on Si wafers do not have an unintentional back-biased junction at the InP/Si interface that occurs in N/P heteroepitaxial cells. For the same emitter thickness, a P/N InP cell has about 100X higher sheet resistance than the N/P cell. In Phase I, Spire attempted to keep the sheet resistance loss of the new P/N cells approximately the same as the 19% N/P cells with 300 A emitters and gridlines on 700 micrometers center- to-center spacings. This resulted in P/N cells with approx. 2400 A emitter thicknesses and 250 micrometers grid spacings. The P/N cells had an 8X thicker emitter, and with the closer gridline spacing had only (250/700) or about 1/3 the photocurrent of the N/P cell flowing to each set of gridlines, so that the closer gridlines reduced the I(squared)R loss by the square of this, or about 8X
Document Details
- Document Type
- Technical Report
- Publication Date
- Aug 16, 1994
- Accession Number
- ADA283624
Entities
People
- Steven J. Wojtczuk