Current-induced thermal tunneling electroluminescence via multiple donor–acceptor-pair recombination

Abstract

The roll-off of quantum yield is a major challenge facing light-emitting diodes due to the inevitable predominant non-radiative recombination with temperature elevation. Here we report highly-efficient intrinsic electroluminescence (EL) from a biased highly-compensated ZnO:Ga (HC-GZO) microrod with a metal–semiconductor–metal (MSM) structure at high temperatures. The origin of the EL emission is the current-induced Joule heating activation of electric-thermal tunneling electrons and the following spontaneous radiation from multiple donor–acceptor-pair (DAP) recombination. The reduced oxygen vacancy (V_O) concentration via Ga doping promotes the electron–phonon coupling to lower the temperature threshold down to ∼650 K, facilitating the stability and durability of MSM-EL devices. Meanwhile, an extra channel of radiative recombination is established by introducing Ga donor dopants, expanding the luminescence color space from orange (0.496, 0.445) to red (0.529, 0.408) by varying the V_O concentration in HC-GZO microrods. The present work motivates research on the mechanism and architectural design for novel electric-thermal tunneling induced efficient radiative emission devices at high temperatures using bandgap-engineered semiconductors.