Effect of amorphous Si capping layer on the hole transport properties of BaSi2 and improved conversion efficiency approaching 10% in p-BaSi2/n-Si solar cells

We investigated the effect of a 3-nm-thick amorphous Si (a-Si) capping layer on the hole transport properties of BaSi2 films. The contact resistance decreased with decreasing resistivity of p-BaSi2 and reached a minimum of 0.35 Ω·cm2. The effect of the a-Si layer was confirmed by higher photoresponsivities for n-BaSi2 films capped with the a-Si layer than for those without the a-Si layer, showing that the minority carriers (holes) were extracted efficiently across the a-Si/n-BaSi2 interface. Under AM1.5 illumination, the conversion efficiency reached 9.9% in a-Si(3 nm)/p-BaSi2(20 nm)/n-Si solar cells, the highest value ever reported for semiconducting silicides.