  We report on the unambiguous detection of Auger electrons by electron
emission spectroscopy from a cesiated InGaN/GaN light emitting diode (LED)
under electrical injection. Electron emission spectra were measured as a
function of the current injected in the device. The appearance of high energy
electron peaks simultaneously with an observed drop in electroluminescence
efficiency shows that hot carriers are being generated in the active region
(InGaN quantum wells) by an Auger process. A linear correlation was measured
between the high energy emitted electron current and the "droop current" - the
missing component of the injected current for light emission. We conclude that
the droop phenomenon in GaN LED originates from the excitation of Auger
processes.
