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, 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 is improved on the thin p-GaN LED compared to previously 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 mechanisms at the surface. Using square root of the light output power as a proxy for the active region carrier density, n, the hot electron integrated peak intensity is shown to be proportional to n3 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.