Effect of Cl-doping in ZnTeO on Photoluminescence and Photovoltaic Properties of ZnTeO-based Intermediate Band Solar Cells

Abstract

We report the effect of Cl-doping in ZnTeO alloys on the photoluminescence (PL) and photovoltaic (PV) properties of ZnTeO-based intermediate band solar cells (IBSCs) with n-ZnS layer. The Cl-doping was done by supplying ZnCl2flux during the growth of ZnTeO on ZnTe substrate by molecular beam epitaxy to introduce electrons into the intermediate band (IB) of ZnTeO that is required to be half-filled with electrons for the efficient operation of an intermediate band solar cell. The ZnCl2 cell temperature was varied between 70 and 250°C. Low temperature PL spectra indicated that the doped Cl atoms acts as donors in ZnTeO. The PV properties of IBSCs using ZnTeO layer with and without Cl-doping were investigated. The external quantum efficiencies (EQE) of the IBSC with Cl-doped ZnTeO are higher than those without Cl-doping in whole energy range between 1.5 and 3.8 eV. The photo current generated by two-step photon absorption through IB was observed at room temperature in the IBSC using Cl-doped ZnTeO whereas it was not detected in the IBSC without Cl-doping. The results indicate that the CI-doping is effective to improve the PV properties of ZnTeO-based IBSC through the introduction of electron into IB.