Schottky-barrier diodes for electron-beam-semiconductor applications

Electron-beam-semiconductor (EBS) targets can be constructed from pn-junction or Schottky-barrier diodes. Most applications described so far have employed the first type of diode. This paper describes the performance and current-gain calculations for Schottky-barrier EBS targets. Experiments and theory show that the current gain of Schottky-barrier diodes is generally greater than that of pn-junctions. Approximate calculations also indicate that the absence of the p+ layer increases significantly the maximum operating frequency of these diodes. The measured current gain characteristics for silicon, gallium-arsenide and gallium-arsenide-phosphide (Ga As0.7P0.3) Schottky-barrier EBS targets are in excellent agreement with theory. Typical current-gains are in the range of 2000 at beam voltages of 12 kv. The performances of the Schottky diodes are compared with those of pn-Junctions for the three semiconductor materials. An important result of these experiments is the derivation of the energies per electron-hole pair for gallium-arsenide (4.6 ev) and gallium-arsenide-phosphide (4.8 ev). It is also shown that Schottky-barrier EBS targets are better suited for measurement of those energies than pn-junctions.