Criteria for improving the properties of ZnGeAs2 solar cells


Correspondence: Timothy J. Peshek, eQED, LLC. Mayfield Village, OH 44143, USA.



We explore the potential utility of the II-IV-V semiconductor ZnGeAs2 as the absorber material in solar cells. As-deposited ZnGeAs2 films prepared by pulsed laser deposition are amorphous because of the limited substrate temperature that can be used without the rapid loss of volatile Zn and As. Thermal processing above 450 °C results in crystallization and improved electrical properties with hole mobilities as high as 58 cm2/V s. The annealed films were used to fabricate p-type ZnGeAs2: n-type CdS cells on SnO2-buffered borosilicate glass substrates in the so-called superstrate geometry. Light-induced currents of up to ~2 mA/cm2 and open-circuit voltages of up to 470 mV were observed using backside illumination, indicating that these nascent devices hold potential for realizing high performance solar cells from earth-abundant elements. The performance of the devices fabricated to-date is degraded by conduction through shorts resulting from the presence of micron-sized pinholes in the absorber layer. Copyright © 2012 John Wiley & Sons, Ltd.