DC Field Distribution in a 'Swept Intrinsic' Semiconductor Configuration

Possible applications have been suggested for semi-conductor configurations involving intrinsic regions adjacent simultaneously to nand p-type extrinsic regions. The basic idea behind some of these proposals is that a suitably large reverse bias voltage (n-regions positive with respect to p- regions) will set up a substantial electric field in the interior of the intrinsic region. This field would sweep most of the mobile carriers out of the intrinsic material, producing a region of material ("swept intrinsic") supporting a large field and having a high resistivity. This paper contains a dc analysis of an idealized one-dimensional swept intrinsic structure with abrupt transitions from strongly n-type to highly intrinsic to strongly p-type material. It gives some quantitative insight into the penetration of the electric field into the intrinsic region as the bias voltage is progressively increased. FORMULATION OF PROBLEM A one-dimensional structure will be considered having the distribution of excess of donor conceptration over acceptor concentration ( Nd-Na ) shown in Fig. 1. It will be supposed that N/rii and P / n , are » 1 and that a reverse bias voltage (Fig. 2) is applied between the bodies of the n- and ?>-type regions, (n, denotes the thermal equilibrium con665