Effect of Doping Density on the Performance of Metamorphic GaInAs Solar Cells Grown by Dynamic Hydride Vapor Phase Epitaxy

Abstract

We study the effect of doping density on the performance of inverted metamorphic ~1 eV GaInAs solar cells grown by dynamic hydride vapor phase epitaxy. We find that the doping efficiency of Se in this material is extremely high, with 5x10¹⁷ cm^-3 being the lowest controlled value we could achieve with our present Se source. We compared rear heterojunction devices grown with intentional n-doping of 5x10¹⁷ cm^-3 and unintentional n-doping of 5x10¹⁵ cm^-3. The intentionally doped sample exhibited an open circuit voltage ~80 mV higher than the unintentionally doped sample due to reduced dark current, and a bandgap voltage offset, or W<inf>OC</inf>, of 0.407 V. We believe that future doping optimization will improve carrier collection and W<inf>OC</inf> in these devices.