Field effect in weakly compensated Si under condition of impurity conduction

Peculiarities of electron transport in a thin (0.5 μm) Si:B layer of p‐channel depletion‐type metal‐oxide‐semiconductor transistors with a high doping level (NA≂1018 cm−3) and a low compensation degree (K≂10−3) are described. These peculiarities manifest themselves in the helium temperature range as an increase and successive saturation of the impurity‐band conductance when the negative charge near the Si surface is increased by applying positive gate voltages. A model is suggested which explains the conduction enhancement as a result of the appearance of an additional channel for hopping in the transition region which divides completely ionized and neutral acceptors. The estimated hopping activation energy is in agreement with the experimental results.