Conductive and Stable Magnesium Oxide Electron-Selective Contacts for Efficient Silicon Solar Cells

DOI: 10.1002/aenm.201601863 level of recombination suppression at the rear surface. When Al is directly deposited on n-type c-Si, however, and even if it is not alloyed with the silicon, the contact behaves in a rectifying fashion and is associated with a high contact resistance, despite the small difference (≈0.1–0.2 eV) that exists between the Al work function and the electron affinity of silicon and the consequently low barrier height predicted by the Schottky–Mott rule.[1,2] This behavior is widely attributed to the Fermilevel pinning phenomenon, induced by a high density of bandgap states or defects at the metal/semiconductor interfaces, which leads to a relatively high Schottky barrier height (ΦB) of ≈0.65 eV that hinders the flow of electrons out of the n-type silicon wafer.[1,2] The approaches for addressing this problem can be inferred by looking into the dependence of contact resistivity ρc, on the Schottky barrier height ΦB, and the surface doping concentration of the semiconductor Nd, which is given by N exp c B