Experimental analysis and 2D-simulation of C-V characteristics in Ag/poly(Si)/ITO/glass Schottky diode

A silver contact with polysilicon fabricated on glass substrates was investigated both experimentally and theoretically by means of measured and 2D-simulated C-V characteristics. The in situ phosphorus-doped polysilicon layer is grown by a low-pressure chemical vapor deposition (LPCVD) technique and crystallized in a vacuum by thermal annealing. The measured C−2-V characteristics of the Schottky contact at two frequencies reveals a linear behaviour at the 10 kHz curve and a distinct non-linear behaviour at the 300 kHz one. Extraction of the frequency independent capacitance by the Kevin method allows the determination of the values of doping concentration (ND = 5 × 1018 cm−3) and Schottky barrier height (ϕb = 0.65 eV). The 2D-numerical simulation code of the Schottky contact C-V characteristics is also developed by considering that the inter-granular traps density NT is localized in the grain boundaries. The effects of the film doping concentration and the trap states density are investigated.