A comprehensive model for MIS (Metal-Insulator-Semiconductor) devices under dark conditions has been developed which consists of a wide range of parameters. The parameters neglected by other authors have been included. The effects of surface states, silicon dioxide thickness, substrate doping, fixed oxide charges, substrate thickness, and metal work function are all taken into account. The permittivity and barrier height of thin oxide are included in the calculation. The limits on equilibrium and nonequilibrium are explored.