The Surface-Barrier Transistor: Part I-Principles of the Surface-Barrier Transistor

This paper, consisting of five parts, describes the principle, fabrication, circuit application, and theoretical bases of a new semiconductor transducer, the surface-barrier transistor. This device, produced by precise electrochemical etching and plating techniques, operates at frequencies in excess of 60 mc while displaying the low-voltage, lower-power-consumption and low-noise properties of transistors hitherto confined to much lower frequencies. Part I describes the basic discovery which led to the new transistor: a new mode of hole injection produced by a broad-area metal electrode in intimate contact with a single crystal of N-type germanium. The mechanisms of hole emission, conduction, and collection are discussed, and the effect on performance of precise fabrication of germanium sections a few microns in thickness is explained. Part II describes typical fabrication methods. A germanium blank is etched by directing to its surfaces two opposed jets of a metal salt solution, through which current passes in such polarity as to remove germanium. In addition to etching away material and disposing of the reaction products, the flowing solution cools the work. The etching is allowed to continue until the thickness of the germanium is reduced to a few microns with a tolerance of ±5 per cent of the remaining thickness. A sudden reversal of polarity then stops the etching action and immediately initiates electroplating of metal electrodes from the salt onto the freshly cleaned germanium surfaces.