Current-Voltage Characteristics of Forward Biased Longp−i−nStructures

Abstract

The current-voltage characteristics have been observed in several germanium $p-i-n$ structures in which the $n$ side was biased negative and the $p$ side positive so as to cause a double injection of electrons and holes into the structure. The middle $i$ section was constructed of good quality germanium (approximately 2×${10}^{13}$ donors/${\mathrm{cm}}^3$) and was many minority carrier diffusion lengths long. The observed $I-V$ characteristics display a low-field region in which the current is proportional to the voltage followed by a higher field region in which the current is proportional to the square of the voltage. In the square-law region, the current is a function of the difference, rather than the sum, of the thermal densities of the electrons and holes. These observations lend experimental support to the basic theories of Lampert and Rose regarding volume-controlled double injection into a semiconductor.