Quantitative correlation of hot electron emission to Auger recombination in the active region of c-plane blue III-N LEDs

Abstract

Using Electron Emission Spectroscopy (EES), measurement and analysis were conducted on the energy distribution of vacuum emitted electrons from an electrically driven InGaN/GaN commercial blue c-plane (peak wavelengths λ ≈ 465 nm) light emitting diode (LED) with 60 nm of p-GaN on top of the active region. The signal-to-noise ratio of semiconductor peaks are improved on the thin p-GaN LED compared to previous published data on thicker p-GaN samples and is attributed to reduced loss of electrons en route to emission into vacuum during transit through the p-GaN. This further proves that hot electrons are generated in the bulk region and not by light or other hot electron generation mechanism at the surface. Using square root of the light output power (LOP) as a proxy for the active region carrier density, n, the hot electron integrated peak intensity is shown to be proportional to n 3 and thus is directly attributed to a 3-body Auger process. Since there are significant Auger recombination currents even at low injection current densities, it is expected that Auger recombination current will dominate over radiation recombination and Shockley-Read-Hall (SRH) currents at higher current densities. This identifies Auger recombination as the dominant cause of efficiency droop.

A Simulation Study of Carrier Capture Ability of the Last InGaN Quantum Well with Different Indium Content for Yellow-Light-Emitting InGaN/GaN Multiple Quantum Wells

“…These defects may act as non-radiative recombination centers, further reducing the efficiency of yellow LED devices [ 3 ]. In addition, under high injection currents, as the potential well of high-In-content InGaN QW is deeper, it is easy to cause an accumulation of a large number of carriers, which may lead to serious Auger recombination [ 4 ] and carrier leakage [ 5 ]. This makes the luminescence efficiency significantly reduced at high currents, resulting in an enhancement of the so-called droop effect for yellow LEDs [ 6 ].…”

Evidence of localization effect on photoelectron transport induced by alloy disorder in nitride semiconductor compounds

“…NEA photoemission spectroscopy is sensitive to the conduction band structure [30][31][32][33]. Furthermore, since the light absorption length is of the order of the electron diffusion length, it provides a unique spectroscopic access to electron transport processes [28,[34][35][36]. This approach allowed us to probe minority electron transport in thin InGaN layers at very low electron concentration, without the limitations of usual electrical transport mea-surements.…”