GaAsP on Si Single-Junction Solar Cells with Enhanced Short-Circuit Current Density Enabled by Distributed Bragg Reflectors

We present the first GaAs0.77P0.23 single junction solar cells on Si with an Al0.20Ga0.80As0.77P0.23/Al0.80Ga0.20As0.77P0.23 distributed Bragg reflector (DBR) to increase long-wavelength quantum efficiency. The 20-period (2.3 μm) DBR achieves reflectance >95.0% in air and a bandwidth of ~55 nm. Thinning the cell' graded buffer and absorber enables DBR incorporation without cracking from thermal expansion mismatch while maintaining a threading dislocation density of 7-8×106 cm-2. The DBR enhances quantum efficiency near the GaAsP cell band edge, increasing the JSC by 1.42 mA/cm2 and efficiency by 1.46% (absolute) over the baseline cell. Overall, we attain an efficiency of 15.06% with a 750 nm thick absorber, showing promise for current-matched GaAsP/Si tandems with improved performance.