TEMPERATURE-DEPENDENCE OF THE FOWLER-NORDHEIM CURRENT IN METAL-OXIDE-DEGENERATE SEMICONDUCTOR STRUCTURES

A comprehensive study of the temperature dependence of the Fowler-Nord heim (F-N) tunnel emission in a metal-oxide-semiconductor structure is conducted both theoretically and experimentally. The theoretical vari ations with temperature of the F-N emission is analyzed both for metal lic and degenerate semiconductor cathode materials. The influence of t he electron concentration of a degenerate semiconductor on the amplitu de of the F-N current is demonstrated. A new analytical formula for th e F-N current temperature dependence is derived from the exact express ions using the Sommerfeld expansion. This new analytical approximation proves to be much more efficient than the previous analytical formula developed by Good and Muller {Field Emission, Handbuch der Physik, Vo l. 21 (Springer, Berlin, 1956)] and may be very useful for F-N current computer-aided-design-oriented numerical simulation. The experimental study of the F-N current in MOS capacitors clearly demonstrates the s trong impact of temperature on the F-N emission above 250 degrees C. I t is also shown that the pre-exponential and the exponential F-N coeff icients can still be determined as a function of temperature. The rela tive variation with temperature of the experimental F-N current data c an be well interpreted by the exact F-N emission formula provided that the temperature dependence of the semiconductor (metal) -oxide barrie r height phi(b) is well accounted for by a quasilinear function of tem perature. The absolute amplitude of the F-N current can also be satisf actorily predicted by the exact F-N theory while adjusting the semicon ductor electron concentration. (C) 1995 American Institute of Physics.