Berlin 2018 – scientific programme

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HL: Fachverband Halbleiterphysik

HL 10: Nitrides: Devices

HL 10.5: Talk

Monday, March 12, 2018, 16:00–16:15, EW 203

Structural and optical properties of In_xAl_yGa_1−x−yN layers for UVB-LEDs — •Tolga Teke¹, Johannes Enslin¹, Gunnar Kusch², Lucia Spasevski², Christoph Reich¹, Bettina Neuschulz¹, Tim Wernicke¹, Robert Martin², and Michael Kneissl¹ — ¹Technische Universität Berlin, Institute of Solid State Physics — ²University of Strathclyde, Department of Physics, SUPA

There are numerous applications for UVB-light emitting diodes (LED) emitting in the range from 280 nm to 315 nm such as UV-curing, phototherapy, and plant growth lighting. However, currently the external quantum efficiency (EQE) of these devices is just in the low percentage range. Several reports have indicated a strong increase of the internal quantum efficiency (IQE) for LEDs with quaternary In_xAl_yGa_1−x−yN quantum wells (QWs). However, detailed studies on how the indium-content influences the IQE, polarizaion fields and carrier localization in the QWs are still missing. In this work, we investigate bulk In_xAl_yGa_1−x−yN layers in order to realize UVB-LEDs with In_xAl_yGa_1−x−yN QWs with different In-content and emission wavelengths near 310 nm. A series of bulk In_xAl_yGa_1−x−yN layers with thickness of 150 nm was grown by MOVPE where the In-content was varied by changing the growth temperature and the In precursor supply. We will present the dependence of the quaternary composition of these layers on the growth conditions determined by wavelength dispersive x-ray spectroscopy (WDX) and its influence on the optical properties by photoluminescence, transmission and cathodoluminescence spectroscopy.