Reactive deposition growth of highly (001)-oriented BaSi2 films by close-spaced evaporation

Abstract

Barium disilicide (BaSi2) is an emerging light-absorbing material for earth-abundant thin-film solar cells. Here, we report scalable and rapid deposition of BaSi2 films by close-spaced evaporation. In this method, BaAl4–Ni evaporation source generates Ba gas, which is deposited on a closely-placed Si(001) substrate. The reaction between deposited Ba atoms and Si substrates yields compositionally homogeneous BaSi2 films through the depth, as evidenced by X-ray diffraction and Auger electron spectroscopy. Although the present BaSi2 films suffer from cracking and exfoliation issues caused by thermal strain, exfoliation is successfully suppressed by lowering the substrate temperature using a reflector. Electron backscatter diffraction and X-ray diffraction analyses show that the dominant orientation of the BaSi2 films is (001). A considerably large single-orientation area more than 68μm was observed, which is the largest among previously reported BaSi2 films.