Fabrication of N+-N iso-type diodes with LPCVD-grown polysilicon on silicon structures

We report the results of fabricating low cut-in voltage, n⁺ -n iso-type diodes using in situ phosphorus-doped polysilicon films on n-type Si substrates. The electrical characteristics of these structures show exponential current-voltage (I-V) behavior. The temperature dependence of the current is used to extract the energy barrier at the film-substrate interface. The formation of the energy barrier is assumed to be due to the presence of energy states at the polysilicon-substrate interface. A simple phenomenological model, which takes into account the interface charge, is presented to explain the formation of the energy barrier. An energy barrier height of about 0.18 eV is extracted from the results of I-V characteristics at different ambient temperatures