The effect of metal work function on current conduction in metal-insulator-semiconductor tunnel junctions

The effect of metal work function on current conduction in metal-insulator-semiconductor (MIS) tunnel junctions has been investigated both experimentally and theoretically. MIS junctions on 2 and 10 Ω cm silicon substrates have been fabricated with both aluminum and magnesium contacts. It is shown that in the region of tunnel-limited current conduction, device characteristics are dependent on the metal work function. The results are in good agreement with predictions from a comprehensive analytical model. The implication of this result for MIS-inversion layer solar cells, where contact current densities are much larger than in transparent metal MIS devices, is examined.