Nitrides Seminar - Andrew Espenlaub, Graduate Student Researcher

3/15/2018 12PM ESB 1008

Abstract:

Auger recombination in the active region of quantum well InGaN light-emitting diodes has been linked to the often large decrease in external quantum efficiency observed at higher forward current densities (a.k.a. – “efficiency droop”), most recently by electro-emission spectroscopy here at UCSB.  This technique for studying Auger recombination in light-emitting diodes has the advantage that it allows the Auger electron’s energy to be observed directly, but it also has some limitations. Two significant ones are that it is only sensitive to eeh Auger processes and that it requires an ultra-high vacuum environment.

 

In this talk I will discuss measurements of photocurrent in forward-biased InGaN light-emitting diodes, and make the case that the observed increase in forward current upon resonant optical excitation of the active region is due to an increase in hot carrier production by Auger recombination in the quantum well.  Photocurrent measurements may be carried out on the optical benchtop and are sensitive to eeh and ehh Auger processes simultaneously, and so are a good complement to electro-emission spectroscopy in the study of the physical origins of efficiency droop in InGaN light-emitting diodes.

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