Berlin 2018 – scientific programme
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HL: Fachverband Halbleiterphysik
HL 33: Poster Session III
HL 33.14: Poster
Wednesday, March 14, 2018, 17:30–19:30, Poster F
Effect of AlGaN quantum well barrier composition on electro-optical properties of 270 nm light emitting diodes — •Jakob Höpfner1, Martin Guttmann1, Christoph Reich1, Luca Sulmoni1, Christian Kuhn1, Pascal Röder1, Tim Wernicke1, and Michael Kneissl1,2 — 1Technische Universität Berlin, Institute of Solid State Physics — 2Ferdinand-Braun-Institut, Leibniz-Institut für Höchstfrequenztechnik, Berlin
Deep ultraviolet (UV) light emitting diodes (LEDs) with emission wavelengths around 270 nm have a wide range of applications such as water purification, sterilization of medical equipment and gas sensing. By varying the composition of the AlGaN quantum well barriers (QB), many properties of the LED can be affected: The injection efficiency, the internal quantum efficienciy and the light extraction efficiency. To investigate these properties, current and polarization dependent electroluminescence measurements of emission spectrum and output power are performed which are then compared to k·p and drift diffusion model calculations. A maximum external quantum efficiency (EQE) was obtained for LEDs with an Al mole fraction of 0.69 in the QB. Furthermore, it was found that the fraction of transverse electric polarized light emission increases and the emission wavelength decreases with increasing Al mole fraction in the QB. This is consistent with k·p calculations, attributing the changes of EQE to changes in the transition probabilities. Drift diffusion model calculations are used to investigate the influence of the properties of the heterostructure on the EQE. Finaly, it will be discussed how to balance the different effects.