An investigation of the current gain of transistors at frequencies up to 105 Mc/s

Abstract

Apparatus is described by means of which the short-circuit current gain is measured directly. Results of such measurements are presented for commercial alloy-junction and surface-barrier transistors; corrections are applied to yield the internal diffusion-current gain. The effects of stray capacitances on the measurements are discussed. The cut-off frequency of the internal current gain is compared with values derived indirectly from other measurements. For alloy-junction transistors the behaviour is closely in accord with existing one-dimensional diffusion theory, with some reservations, but for surface-barrier transistors the agreement is less close.