Regensburg 2019 – scientific programme
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HL: Fachverband Halbleiterphysik
HL 35: HL Poster II
HL 35.17: Poster
Wednesday, April 3, 2019, 17:30–20:00, Poster E
MOVPE Growth of Semipolar (11-22) Al0.8Ga0.2N on (10-10) Sapphire — •Sarina Graupeter, Humberto M. Foronda, Frank Mehnke, Tim Wernicke, and Michael Kneissl — Institute of Solid State Physics, Technische Universität Berlin
AlGaN materials grown along the polar c-axis are the most common approach to realize optoelectronic devices in the deep ultraviolet spectral range. However, the external quantum efficiency (EQE) at emission wavelenghts below 240 nm drops drastically. This can be explained by the light emission polarized with electrical field vector parallel to the c-axis with increasing aluminum content. UV emitters grown on semipolar AlGaN offer a promising alternative due to the improved light extraction and the reduced quantum confined stark effect (QCSE). In this study we investigate the growth of semipolar AlGaN on m-plane sapphire by metalorganic vapor phase epitaxy (MOVPE). However, the growth of high quality semipolar AlGaN layers is challenging due to the simultaneaus formation of crystallites with other orientations leading to a deterioration of layer quality. We investigated the influence of growth parameters on the surface morphology and density of misoriented grains to achieve high quality AlGaN buffer layers. Variations of the reactor pressure, V/III ratio and metal organic flows all influenced the grain density. By analyzing the data we found that the grain density is correlated mainly to the growth rate. By growing a buffer layer 0.15 µm/h a grain density as low as 3· 106 cm−2 was achieved. This was grain density was preserved also when subsequent layers where grown at higher growth rates.