In this article, it is theoretically analyzed that when there are surface states and there is no external voltage, the energy zones of the semiconductor are bent, that is, there is an electric field introduced at the border of the semiconductor-dielectric separation. The presence of such a field affects the closing voltage of the channel, the slope of the volt-ampere characteristic, the stock current in saturation conditions, and the frequency and temperature parameters of the transistor. As an example, a series of volt-ampere characteristics obtained at room temperature at different values of the voltage applied to the gate of the field-effect transistor KP 102 with an input channel isolated gate with ntype conductivity is presented. As can be seen from the results, when the voltage between the stock and the source exceeds 4 V, the stock current of the transistor reaches saturation and does not depend on the voltage.