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Technological challenges >> Solid state physics, surfaces and interfaces
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Qualification and quantification of GaN, InGaN and AlGaN surface states :

Département d'Optronique (LETI)

Laboratoire des Composants Emissifs

01-09-2021

SL-DRT-21-0515

David.Vaufrey@cea.fr

GaN-based µLEDs seem promising for augmented reality (AR) or virtual reality (VR) applications. Indeed, they would make it possible to produce screens with resolutions and luminances that had not yet been achieved. But these µLEDs suffer from a lower efficiency compared to their larger sibling. A commonly accepted explanation for this efficiency degradation lies in the existence of numerous surface defects induced by pixel singularization etching. The smaller the dimensions of the LED, the more important the surface defects play in the electro-optical behavior. Their presence, if they are shallow, can facilitate electrical injection, on the other hand if they are deep, they contribute to the degradation of the electro-optic performances of devices such as LED. This thesis aims to quantify and qualify the surface defects in GaN, InGaN and AlGaN that make up GaN-based µLEDs. The doctoral student will have to carry out by himself all the stages of realization of new components necessary for this study, starting with the design of the photolithography masks, the realization of all the technological steps and finally the electro-optical characterizations such as DLTS (Deep Level Transient Spectroscopy), DLOS (Deep Level Optical Spectroscopy) or photocurrent. At the end, the doctoral student will have to identify the surface defects that are the most limiting for the efficiency of LEDs and the most favorable to the injection of electrical carriers. The thesis will be carried out in close collaboration with Ph Ferrandis (thesis director) from Néel Institute (CNRS), N. Rochat (co-supervisor) from CEA Leti (PFNC Nano Characterization Platform) and David Vaufrey (supervisor) from CEA Leti (LCEM Emissive Device Laboratory). The thesis grant would be fully funded by the CEA Leti in Grenoble for a period of 3 years.

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