Point contact rectifier theory

Point contact rectifiers have long been reputed to be unsusceptible to analysis. Although some features of their behavior are still poorly understood, there are a number of aspects which probably can be described quantitatively. In these cases, the difficulties are due to the complexity of the mathematical analysis rather than a lack of basic understanding. The approaches used in the theoretical analysis of two aspects of point contacts are discussed: the forward characteristics at moderately high currents, and the breakdown in the reverse direction. For the former, a theoretical solution is obtained for a hemispherical p-n junction. The computed curves agree qualitatively with experimental ones; a quantitative check is complicated by the need to compute curves for many different parameters. The breakdown properties of a point contact diode are compared with the theory for avalanche breakdown in a junction where heating occurs. Again, quantitative comparisons have not yet been made, but qualitative agreement encourages one to use the theory for obtaining design criteria in developmental work.