This manuscript reports on an analytical study required to determine and enhance the effect of the high–low junction based back surface field (BSF) of thin n-CdS/p-SiGe/p+-BaSi 2 heterojunction solar cell. A 0.3 µm thick BSF layer made of extensively available and low-cost barium silicide (BaSi 2) is introduced into the basic SiGe solar cell for the first time. SCAPS-1D simulator is employed to analyze different parameters such as open circuit voltage (V oc), short-circuit current density (J sc), fill factor (FF), quantum efficiency (QE) and conversion efficiency (η) of the device. The SiGe absorber layer thickness is varied from 2 to 50 µm to analyze the device performance, however optimum results are observed between 10 and 15 µm. The BSF BaSi 2 layer thickness changing from 0.1 to 0.8 µm to check the viability of device for optimal efficiency. The present structure anticipates an efficiency of 17.05% for BSF layer thickness of 0.8 µm. In addition, the use of SiGe earth abundant material instead of CIGS having rare earth metals indium and gallium, reduces the overall fabrication cost of the solar cell.