Te Doping Effect of InGaP in Tunnel Junction on the Performance of InGaP/InGaAs/Ge Triple-Junction Solar Cells

Tellurium (Te) doping of InGaP with diethyl Te (DETe) was investigated to apply for tunnel junctions (TJs) in multijunction solar cells. When the DETe flow rate was 2 sccm, the electron concentration was found to increase with decreasing growth temperature. The obtained electron concentration reached up to ~1 × 1019 cm
^-3
. The photovoltaic (PV) properties of InGaP/InGaAs/Ge triple-junction solar cells with a Te-doped InGaP layer in TJ were measured under concentrated light condition. Here, Te-doped InGaP layers in TJ were prepared using different growth temperatures ranging from 540 °C to 660 °C. Compared with other samples, open-circuit voltage (VOC), fill factor, and conversion efficiency were higher for the sample with an InGaP grown at 570 °C. For this sample, external quantum efficiency was also found to be higher than the other samples, associated with the improved crystalline quality.