Extensive analysis of band alignment engineering on the open circuit voltage performance of a GaAs/GaSb hetero structure solar cell

Abstract

Maximum use of solar spectrum is possible through the selection of suitable band gap material in a solar cell. Single junction hetero structure solar cell provides a better opportunity by opting different materials with different band gap in the preparation of such device. But the problem arises with the large lattice mismatch and band discontinuity among these materials, which drastically reduces the open circuit voltage $(\mathrm{V}_{\mathrm{oc}})$ as well as the fill factor of the cell. In this work, band alignment engineering has been introduced for such type of problems. The device is simulated and verified using Silvaco TCAD suite. An extensive study is carried out in terms of SRH, radiative recombination and its effect on $\mathrm{V}_{\mathrm{oc}}$ of the cell for different band offset values. It is found that the reduction in band discontinuity improves the $\mathrm{V}_{\mathrm{oc}}$ of the device.