Further research into the differential charge pumping effect in MOS-transistors

The behavior of a metal oxide semiconductor-transistor under small variations of the gate potential about an equilibrium value is described. The change in the charge carrier concentrations in the bands as well as in the interface states in the forbidden zone is discussed in terms of an equivalent scheme, the elements of which depend solely on the equilibrium quantities. It was found that the finite averaged substrate current is about 103 to 104 times smaller than the amplitude of the alternating current described by linear relations. This effect is termed 'charge pumping'. The effect of diffusion of electrons from the bulk substrate to the surface and of holes through the weak inversion layer is also taken into account. It is shown that the effect of the diffusion is negligibly small for elements with low state densities at the interface.