Electrical properties of metal-polymer (polysterene) silicon devices

The electrical properties of metal-polymer-silicon (MPS) structures have been investigated. Polymer films have been deposited on silicon substrates by using polymerization of a styrene monomer vapor in an ac glow discharge. A close examination of the hysteresis shown in the C(V) curves of the MPS capacitors has been made. The sense of this hysteresis reverses when the bias-sweep frequency is reduced. The variation of the flat-band voltage shift when the polarizing voltage varies with regular steps between symmetrical extremes is determined with respect to hysteresis. It is shown that the effect of temperature is very important in the variation of the flat-band voltage shift. This variation is appreciably symmetrical when a polarizing voltage step is applied to the structure and when it is short circuited. It may be concluded that the charge variations leading to the hysteresis effect of the dynamic capacitance curve are due to injection of carriers in the polymer film from both the metal and the silicon over the potential barrier present at these interfaces. A model is proposed to express the method of carrier injection.