Entirely diffused vertical channel JFET: Theory and experiment

The experimental electrical properties of a vertical channel JFET fabricated by a double diffusion technique are presented. A table showing its principal characteristics for different values of the diffusion depths is included. The analysis of the "triode-like" operation revealed by the output characteristics is based on a two-dimensional numerical simulation of the device. At high drain currents I_D is proportional to V_DS^α ( α<1). This behaviour can be attributed mainly to the effect of channel length modulation by the drain voltage. At low drain currents, the potential barrier between the source and the drain determines the current magnitude. This is an exponential function of the barrier height which increases almost linearly when V_GS increases and decreases non-linearly when V_DS increases.