The effects of nitrogen trifluorideinthe gas stream during deposition of semi-insulating polysilicon (SIPOS) on the electrical characteristics of undoped (SIPSO)/p-Si, and n+-SIPOS/n-Si isotype junctions were investigated. The current-voltage characteristics of undoped SIPOS/p-Si heterojunctions exhibit a strong dependence on the oxygen content of the SIPOS film and depart from a hyperbolic sine behavior as the refractive index of the SIPOS increases.. The addition of nitrogen trifluoride decreases the current density of these undoped SIPOS/p-Si heterojunctions due presumably to the oxidation/hydrolysis of SiF species intoSiO2. The n+-SIPOS formed a rectifying isotype junction o n-Si. The forward current voltage characteristics exhibit two distinct activation energies separated by a "kink" in the forward semi-logarithmic characteristics; one below the cut-in voltage and one above the cut-in voltage. The two activation energies result from the presence of interface states in the structures. However, the forward current-voltage characteristics of the fluorinated SIPOS isotype junctions exhibit no "kink" and only a single activation energy due, presumably, to hydrogen passivating the interfacial traps during the hydrolysis process.
Ranade, R. M.; Ang, S. S.; and Brown, W. D.
"Semi-Insulating Polysilicon Hetero- and Isotype Junctions on Silicon,"
Journal of the Arkansas Academy of Science: Vol. 47
, Article 24.
Available at: http://scholarworks.uark.edu/jaas/vol47/iss1/24