A transition from triode-like to pentode-like

characteristics is observed in diffusion-type vertical JFET\´s by varying the channel impurity concentration from 5 × 10
14to 5 × 10
15cm
-3. In calculated

characteristics of a low concentration and short-channel JFET, Geurst\´s theory has been shown to agree qualitatively with the experimental curves. In a triode-like JFET, drain currents show two distinct drain-voltage-dependent regions. It has an exponential dependency when the drain current is less than 0.2 mA . cm
-1. It has an

th power depndency on the drain voltage when the drain current is larger than 5 mA . cm
-1. Other important electrical properties are also calculated and compared with experimental data.