On the forward bias excess capacitance at intimate and MIS Schottky barrier diodes with perfect or imperfect ohmic back contact

An experimental explanation of the forward bias Capacitance;frequency plots for intimate or MIS SBDs with perfect or imperfect ohmic back-contact has been made. It has been shown that there is no excess capacitance that could be ascribed to the interface states or minority carrier at the intimate SB Ds (that is, without interfacial layer) with the perfect ohmic back contact (low-resistance). It has been found that the excess capacitance is only me asurable at SBDs with imperfect back contacts or with an interfacial layer which separates the interface states from the metal. It has been found that excess capacitance can be generated by varying the resistance or quality o f the back-ohmic contact to the bulk semiconductor substrate, that is, the density of minority carriers that are injected by the Schottky contact depe nds sensitively on the properties of the ohmic back-contact. Again, it has been seen that the excess capacitance has appeared owing to the interface s tates plus minority carriers in MIS SBDs with imperfect back contacts. Thus , it has been concluded that the excess capacitance at nonideal Schottky co ntacts has been caused not only by the interface states but also by the min ority carriers or by the interface states plus minority carriers due to the poor frontside or poor backside contacts. Thereby it has been experimental ly shown that every forward bias C-f-plots with excess capacitance cannot b e used to extract the results related to the interface states.