Electrical characteristics of metal-dielectric-metal and metal-dielectric-semiconductor structures based on electron beam evaporated Y2O3, Ta2O5 and Al2O3 thin film

This work examines the electrical properties of metal-dielectric-semiconductor (Au/Ti-D-pSi) and metal-dielectric-metal (Au/Ti-D-Pt/Ti-pSi) capacitors which incorporate as dielectrics Y2O3, Al2O3 and Ta2O5 films evaporated by an electron beam at room temperature. The emphasis of the results is twofold: the first is the high quality of the investigated films as evidenced by the small measured values of loss factor, flatband voltages, and surface states density as well as the low dispersion of the relative dielectric constants. The second is an analytical procedure for discrimination of current flow mechanisms, under different regimes of applied voltage. A detailed study of the power exponent parameter a = d (Log I)/d(Log V) was found to be superior to conventional graphical representation of I - V data. The dominant mechanisms of charge transport through the metal-dielectric-metal structures was found to be the Schottky emission for Y2O3, and Al2O3 at low electrical fields. For structures with Y2O3 and Ta2O5 films operating in the high field regime, the charge transport mechanism is mainly space charge limited current. (C) 1998 American Institute of Physics. [S0021-8979(98)01723-X].