High-temperature annealing effects on molybdenum-silicon contact substrate for vertically structured silicon quantum-dot solar cells

This paper studies the applicability of sputtered Molybdenum (Mo) thin films on silicon wafers (Mo-Si) to act as contact substrates for vertically structured Si quantum-dot (QD) solar cells. The compatibility of Mo-Si contact substrate with Si QD material under different annealing temperatures is examined. Cross sections of annealed samples show well-defined interfaces without metal penetration into the Si QD bilayer regions. Through comparing samples deposited on Mo-Si substrates with those on fused-silica substrates, we identified from Raman spectra that the presence of Mo is advantageous for the Si-crystallization process and in fact provide beneficial passivation effects on the Si QD material according to changes in photoluminescence intensity. This allows us to conclude that Mo thin films are compatible with the sputter-anneal process, and verify the feasibility of using the proposed Mo-Si contact scheme for future fabrication of Si QD solar cells.