Structural design of BaSi2 solar cells with a-SiC electron-selective transport layers


 Sputter-deposited polycrystalline BaSi2 films capped with a 5-nm-thick a-SiC layer showed high photoresponsivity. This means that the a-SiC layer functions as a capping layer to prevent surface oxidation of BaSi2. Based on the measured absorption edge and the electron affinity of the a-SiC layer and the work function of the TiN layer, the a-SiC is considered to act as an electron transport layer (ETL) for the BaSi2 light absorber layer/a-SiC interlayer/TiN contact structure in a BaSi2 solar cell. Using a 10-nm-thick p+-BaSi2 layer as a hole transport layer, we investigated the effect of the BaSi2/a-SiC layered structure on the device performance of a BaSi2-pn homojunction solar cell by a one-dimensional device simulator (AFORS-HET v2.5). The a-SiC ETL effectively separates photogenerated carriers and allows transport of electrons while blocking holes to achieve an efficiency of 22% for a 500-nm-thick BaSi2 light absorber layer.