FIELD-EFFECT IN WEAKLY COMPENSATED SI UNDER CONDITION OF IMPURITY CONDUCTION

Peculiarities of electron transport in a thin (0.5 mum) Si:B layer of p-channel depletion-type metal-oxide-semiconductor transistors with a high doping level (N(A) congruent-to 10(18) cm-3) and a low compensati on degree (K congruent-to 10(-3)) are described. These peculiarities m anifest themselves in the helium temperature range as an increase and successive saturation of the impurity-band conductance when the negati ve charge near the Si surface is increased by applying positive gate v oltages. A model is suggested which explains the conduction enhancemen t as a result of the appearance of an additional channel for hopping i n the transition region which divides completely ionized and neutral a cceptors. The estimated hopping activation energy is in agreement with the experimental results.