Impact of Passivation on Base Thickness for Single Junction Flexible GaAs Solar Cells on Epi-ready Metal Tape

We have demonstrated GaAs single junction solar cells on epi-ready low-cost flexible metal tape and studied the impact of passivation on base thickness of the fabricated device. In our process, single-crystalline-like germanium films are grown on the flexible metal tape over which epitaxial (Al)GaAs semiconductor thin films are grown by metal organic chemical vapor deposition (MOCVD). The grown device architecture was modified with different GaAs base thickness. Passivation using citric acid for GaAs with thinner base of 378nm resulted in reduction of leakage current by two orders of magnitude more than that with thicker base of 1137nm. Photon conversion efficiency greater than 6% with open circuit voltage (V
_OC
) of 560mV, short circuit current density (J
_SC
) of 16.8mA/cm
²
and fill factor (FF) of 69% was observed under A.M 1.5 (1 sun) after surface passivation and anti-reflection coating (ARC). Further improvement in device efficiency is achieved with new device architectures, optimization of the growth, different means of passivation and improving fabrication processes.