Internal Field Emission at Narrow Silicon and Germaniump−nJunctions

A detailed study has been made of the reverse characteristics of several silicon and germanium alloyed $p-n$ junctions with breakdown voltages in the range of about 0.1 to 0.8 volt. In these junctions the reverse current is generated almost entirely by internal field emission (tunneling). The reverse bias characteristics are insensitive to the dislocation density present so that the tunneling current occurs mainly in undistorted material. From capacitance studies it is established that these narrow junctions are very close to being ideal step junctions. The room-temperature reverse characteristics are analyzed in terms of the usual tunneling probability expressions and in particular, good agreement, both qualitative and quantitative, is found between experiment and theory. The tunneling probability $\exp (-\frac{\alpha {\epsilon }^{\frac{3}{2}}}{E})$, when compared with experiment, yields values for $\alpha {\epsilon }^{\frac{3}{2}}$ in agreement with the theoretical ones to within a factor of less than 2 for both silicon and germanium.