Nature of current and of forward-bias electroluminescence excess noise in GaAs-diodes

Abstract

The excess fluctuations of the direct current and of the forward-bias electroluminescence intensity in GaAs-diodes have been investigated. The diodes of two types have been studied: the samples doped by non-amphoteric impurities (type I diodes) and the samples doped by non-amphoteric together with amphoteric impurities (type II diodes). The current noise in type I samples as well as in the wide current range in type II samples is shown to be generated in the space charge region of diodes. These noises are as a matter of fact the fluctuations of the excess component of the whole current which is likely to pass through some ‘peculiar’ regions of p- n-junctions rather than through the whole area. The current noise observed in type II diodes at sufficiently large currents is due to the fluctuations of the resistance of the compensation region of the diode or due to the fluctuations of its contact resistance. The excess electroluminescence noise in all diodes investigated has been found to be connected with the above-mentioned fluctuations of the excess component of the whole current and in the type II samples the over-barrier electron flow responsible for the electroluminescence passing probably through the same ‘peculiar’ regions of p- n-junction as the excess current does.