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Duvet

PROJECT AT A GLANCE

DUVET project was started January 1, 2018, for a duration of 36 months. It aims at developing tunnel junctions for UV LEDs.

Light Emitting Diodes (LED) based on nitrides are very efficient and worldwide used for solid state lighting. In the ultraviolet, however, their wall plug efficiency remains severely limited by the p doping problem in AlGaN. This intrinsic problem can be circumvented by inserting a tunnel junction, which allows injecting holes in the LED and replacing the p contact by an n contact. The challenge is to obtain a low resistance in this tunnel junction in order to maximize the overall LED efficacy. The project aims at exploring all solutions to fabricate this junction, in particular the insertion of a thin InGaN layer in AlGaN, at studying carefully the role of defects in the junction and the physics of hole injection. A breakthrough in this domain would have a tremendous impact. For instance, water sterilization with UV at 275 nm could be easily extended in many countries and would allow saving thousands of lives in underdeveloped countries. A consortium of 3 laboratories (CRHEA, LETI, IEMN) will tackle this problem. TJs will be grown by a combination of gas phase and molecular beam epitaxies, which solves a problem of Mg activation. The role of defect at the interface, which is believed to increase the tunnel current, will be investigated by surface treatments, and chemical analyses, coupled with electrical measurements. The injection of out of equilibrium holes will be studied by growing dedicated structures. The goal is to reach a tunnel junction resistance lower than 0.001 ohmcm2 in TJ for LEDs emitting at 310 and 275 nm, and a wall plug efficiency of 1% at 275 nm.

Partners

Partner 1

The coordinator laboratory, CRHEA (Sophia Antipolis) is specialized in the epitaxy of wide band gap semiconductors. CRHEA is coordinating GaNeX LABEX dedicated to GaN. In DUVET, CRHEA will be in charge of the epitaxy, process and electrical measurements.

Partner 2

CEA-LETI is a recognized center on micro-nano-technologies. In DUVET, LETI will measure the defects at the TJ interface, using the Grenoble nano-characterization facility (PFNC) which gathers the most sophisticated tools for chemical and structural analysis.

Partner 3

IEMN (Lille) is a recognized center on microelectronics, developing technology and measurements in various materials (Si, GaAs, GaN, …). In DUVET, IEMN will be in charge of low temperature, noise and early reliability measurements. IEMN will also provide a backup for processing in case of technical problems in processing at CRHEA.