Abstract :
Hole storage is an effect which takes place in semi-conductor valves using n-type base material; it has a counterpart in electron storage in p-type material. It gives rise to several electrical effects, particularly to transient reverse currents in diodes on the application of a reverse bias. The effects are deduced, quantitatively, by solving the continuity equation with boundary conditions appropriate to the geometry and the external circuit. Planar and hemispherical diodes are analysed separately, although the former is only a special case of the latter. Parts of the analyses assume a reverse voltage to be applied immediately following the passage of forward current; another part assumes delay and calculates the decay of floating potential which results. Both significant and negligible limiting of the transient reverse current, by the external circuit, are considered. The analyses are tested by experiments, particularly some using modulation techniques, and used to deduce the hole lifetime in the base material of experimental diodes. Fair agreement is recorded between methods based on measurements of (a) the decay of current at short and at long times after the application of reverse bias, (b) the duration of limiting, and (c) the decay of floating potential. The extent to which the analyses apply to point-contact diodes remains debatable, in view of Waltz´s observations and the difficulty of obtaining quantitative confirmation with commercial diodes.
