Dense electron-hole plasma in silicon light emitting diodes

TL;DR

This paper demonstrates that dense electron-hole plasma self-compression in silicon LEDs explains their high efficiency and spectral properties, supported by experiments and theoretical considerations of plasma attraction mechanisms.

Contribution

It introduces the concept of plasma self-compression in silicon LEDs as a key factor for efficient electroluminescence, supported by experimental evidence and theoretical analysis.

Findings

High quantum efficiency achieved in silicon LEDs.

Electroluminescence intensity linearly depends on diode current.

Spectral emission shifts are explained by plasma self-compression.

Abstract

Efficient electroluminescence of silicon light emitting p-n diodes with different sizes and shapes is investigated at room temperature. High quantum efficiency of the diodes, a long linear dependence of the electroluminescence intensity on the diode current and a low energy shift of the emission line in electroluminescence spectra with increasing diode current are explained by the self-compression of injected electron-hole plasma into dense electron-hole plasma drops. Experiments on space scanning of the electroluminescence intensity of the diodes support this conclusion. The plasma self-compression is explained by existence of an attraction in electron-hole plasma, compensating the plasma pressure. A decrease of the semiconductor energy gap due to a local lattice overheating, produced by the plasma, and the exchange-correlation interaction could contribute to this attraction. The self-focusing of the injection current can accompany the plasma self-compression.