Dresden 2014 – wissenschaftliches Programm

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HL: Fachverband Halbleiterphysik

HL 19: Nitrides: Devices

HL 19.3: Vortrag

Montag, 31. März 2014, 15:30–15:45, POT 151

( 1122 ) InGaN/GaN LEDs grown on 2" patterned sapphire substrates — •Tobias Meisch1, Sabine Schörner2, Junjun Wang1, Klaus Thonke2, and Ferdinand Scholz11Institute of Optoelectronics, University of Ulm, 89081 Ulm, Germany — 2Institute of Quantum Matter, Workgroup Semiconductor Physics, , University of Ulm, 89081 Ulm, Germany

We have grown high quality ( 1122 ) GaN on ( 1012 ) patterned sapphire. The patterning of the substrate was done by reactive ion etching to produce periodic trenches with a depth of about 1.5 µm and a width of 1.5 µm, revealing a c-plane-like facet on one side. In the following MOVPE process, GaN nucleates on this unmasked side facet, grows out of the trench and forms a coalesced semipolar surface. By comparing the doping behavior of c-plane and ( 1122 ) GaN, a significant reduced magnesium incorporation efficiency on the semipolar surface was detected. To achieve similar electrical properties, an about 10 times higher Mg flux is necessary. However, making use of this conclusion, now we are able to grow LEDs on ( 1122 ) GaN. Therefore, five InGaN quantum wells with GaN barriers are deposited on an about 1 µm thick silicon doped GaN layer. On the top, a 200 nm thick p-doped GaN layer was grown. First EL measurements show very promising results: At 20 mA, an optical output of 0.2 mW at 450 nm was achieved. By increasing the indium flux step by step, the emission wavelength could be shifted to 475 nm. Adjusting the QW properties and inserting an InGaN pre-QW should help to increase the output power further.

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