Detection of hot electrons originating from an upper valley at ∼1.7 eV above the F valley in wurtzite GaN using electron emission spectroscopy

Using electron emission spectroscopy, measurement and analysis were conducted on the energy distribution of vacuum emitted electrons from electrically driven InGaN/GaN green (peak wavelengths lambda approximate to 515 nm) light emitting diodes (LEDs) with and without a prewell superlattice (SL). We report on the detection of a high-energy upper valley at similar to 1.7 eV above the I' valley from samples with no prewell SL. We propose that these upper valley electrons originate predominantly from trap-assisted Auger recombination (TAAR) in green LEDs, as the intensity of these peaks is found to have quadratic dependence on the carrier density n [see Espenlaub et al., J. Appl. Phys. 126, 184502 (2019)]. The high-energy upper valley peak was not observed in the sample with a prewell SL which is attributed to gettering by the prewell SL of still unidentified impurities that act as TAAR centers.

Automated summary

Using electron emission spectroscopy, researchers measured and analyzed the energy distribution of vacuum emitted electrons from electrically driven InGaN/GaN green light emitting diodes (LEDs) with and without a prewell superlattice (SL). They discovered a high-energy upper valley peak at approximately 1.7 eV above the I' valley in samples without a prewell SL, which is attributed to trap-assisted Auger recombination (TAAR). The absence of this peak in the sample with a prewell SL suggests the gettering of unidentified impurities that act as TAAR centers.