THE EFFECT OF FIXED SPACE-CHARGE ON SPACE-CHARGE-LIMITED CURRENT INJECTION IN IMPURITY-BAND-CONDUCTION SEMICONDUCTORS

A theoretical study has been made of the effect of fixed space charge, both negative and positive, on space-charge-limited (SCL) current injection in impurity-band-conduction (IBC) semiconductors. IBC refers to semiconductors that are either n- or p-type and sufficiently doped to enable hopping conduction to occur. This feature allows one to create a fixed space charge by depletion of the hopping carriers. The topic is of practical interest because of space charge effects on current vs bias behavior. Calculated values of current vs applied bias are presented. It is shown that IBC space-charge fields behave in the same manner as blocking contacts, in that they both shift upward the magnitude of the critical bias where the onset of current injection occurs. Thus the use of IBC semiconductors may prove to be of value in those areas of device physics where control of injected current is of interest.