I-V CURVE SHAPE FACTOR FOR THIN P-N-JUNCTIONS AT HIGH INJECTION LEVELS

Modeling of the I(V, T) dependence in thin p-n semiconductor structure s shows that various behaviors in its shape factor can be correlated w ith and explained through the voltage dependence of the carrier concen tration product np and its components, at the zero field injection-poi nt, for various conditions controlled by thickness and doping. A ''sec ond exponential'' high injection range exp (qV/nkT), with a shape fact or n as high as four appears to be a consequence of the departure from quasineutrality due to significant minority carrier space charge, fav ored by low doping and thickness. In thin structures, the presence of a second exponential range is associated with the presence of a quadra tic range (I similar to V-2) at very high current densities.