Current and electroluminescence intensity oscillations under bipolar lateral electric transport in the double-GaAs/InGaAs/GaAs quantum wells

Abstract

The lateral bipolar electric transport has been investigated for multi-period n-In 0.08 Ga 0.92 As/GaAs heterostructures with tunnel-coupled double-quantum wells for various carrier mobilities at temperatures 4.2...160 K. The presence of two types of charge carriers – electrons and holes – is identified by observation of interband electrolumine- scence (EL). We found that the current-voltage characteristic has a complex nonlinear shape and changes with current, which is accompanied by modification of the EL intensity and spectrum. We observed oscillations of the current and EL intensity with the frequency of tens MHz, both arise at the electric fields well below the threshold field of the Gunn instability. Oscillations of the EL intensity occur in the opposite phase to the current. The electric and EL measurements have shown that the minority carriers, the holes, are supplied from the anode side of the sample. Spatial separation of electrons and holes in the double- quantum well structures provides abnormally large both electron-hole recombination time and drift length of the holes. Studied behavior of the current and EL can be interpreted as a combined effect of the spatial separation of the electrons and holes and dynamics of their transfer between undoped and doped quantum wells. We suggest that observed real-space transfer effects in high-field bipolar electric transport and, particularly, highly intensive interband electroluminescence from macroscopically large areas may be used in a number of optoelectronic applications.

Keywords

• quantum wells
• current oscillations
• lateral electric transport
• negative differential conductivity