Silicon Schottky Barrier Diode with Near-Ideal I-V Characteristics

Metal-semiconductor (or Schottky) barriers have been studied extensively in the past few years. The main concerns are the barrier height and the current transport in the metal-semiconductor system; the former has been reviewed recently by Mead, 1 and the latter discussed by Crowell and Sze.2 Most emphasis has been placed on the forward current-voltage characteristic, which relates intimately to the electronic applications of Schottky diodes such as varistors for logic gates and microwave downconverters. The reverse current-voltage characteristic of a conventional planar Schottky diode,3 usually has had greater leakage current and lower breakdown voltage than a diffused p-n junction. Because of this "soft" reverse characteristic, Schottky diodes have not been considered for power application, as well as IMPATT oscillators. 195 196 T H E BELL SYSTEM TECHNICAL JOURNAL, FEBRUARY 1968 It should be pointed out, however, that if the reverse characteristic can be improved substantially, a Schottky diode with its inherent majority transport property, can be used as a high-speed switch in which there is virtually no minority carrier storage, and as a highpower rectifier or high-frequency oscillator where the region of greatest heat dissipation is located right at the metal-semiconductor interface and therefore the heat can be more readily conducted away. The soft breakdown of conventional Schottky diode is not caused by the electron tunneling effect but results mainly because of the "edge effect" shown in Fig.