CALCULATION OF THE AVERAGE INTERFACE FIELD IN INVERSION-LAYERS USING ZERO-TEMPERATURE GREENS-FUNCTION FORMALISM

We investigate the dependence of the average interface field on the in version and depletion charge density through the use of a zero-tempera ture Green's function formalism for the evaluation of the broadening o f the electronic states and conductivity. Various models for the surfa ce-roughness autocovariance function existing in the literature, inclu ding both Gaussian and exponential models, are studied in our calculat ions. Besides surface-roughness scattering, the dominant scattering me chanism at high electron densities, charged impurity, interface-trap a nd oxide charge scattering are also included. The position of the subb and minima, as well as the electron wave functions, are obtained by a self-consistent solution of the Schrodinger, Poisson, and Dyson equati ons for each value of the inversion charge density. Many-body effects are included by considering the screened matrix elements for the scatt ering mechanisms and through inclusion of the exchange-correlation ter m. The dependence of the mobility and the effective field upon the inv ersion charge density is Sensitive to the model chosen, and we discuss the manner in which this may be used to study the interface itself. ( C) 1995 American Vacuum Society.