Mechanisms of charge carrier transport in polycrystalline silicon passivating contacts

We use temperature-dependent contact resistivity (?c) measurements to systematically assess the dominant electron transport mechanism in a large set of poly-Si passivating contacts, fabricated by varying (i) annealing temperature (Tann), (ii) oxide thickness (tox), (iii) oxidation method, and (iv) surface morphology Si substrate. The results show that for silicon thicknesses 1.3–1.5 nm, changes from tunneling drift-diffusion via pinholes SiOx layer increasing Tann. This transition occurs Tann range 850°C-950 °C 1.5 nm thick thermal oxide, 700°C-750 1.3 wet-chemical which suggests appear oxides after exposure lower budgets compared oxides. For with tox = 2 grown either thermally or plasma-enhanced atomic deposition, carrier is pinhole-dominant 1050 °C, whereas no electric current through could be detected Remarkably, not affected substrate morphology, although values ?c were measured on textured wafers planar surfaces. Lifetime suggest best selectivity can achieved choosing right above range, but too high, order induce pinhole while preserving good passivation quality.