Berlin 2018 – scientific programme

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HL: Fachverband Halbleiterphysik

HL 22: Nitrides: Preparation and characterization I

HL 22.2: Talk

Tuesday, March 13, 2018, 14:15–14:30, EW 203

Microscopic interface and composition analysis of one-directionally lattice-matched AlInN — •Philipp Horenburg, Heiko Bremers, Ronald Korn, Uwe Rossow, and Andreas Hangleiter — Institute of Applied Physics, TU Braunschweig, Germany

We present microscopic evidence of interfacial indium depletion in c-lattice-matched AlInN grown by metalorganic vapor phase epitaxy on m-plane GaN. Further, in contrast to reports from the literature, we see no hints at parasitic gallium incorporation into the AlInN.

It is well known that lattice matching to GaN can be achieved in various crystal orientations. However, as the ideal growth conditions of its binary constituents AlN and InN are fairly different, epitaxy of AlInN remains a complex endeavour with a small window of suitable growth parameters. We performed a series of high-angle annular dark field (HAADF) and energy-dispersive X-ray spectroscopy (EDS) measurements at the AlInN/GaN interface. In a quantitative analysis, it becomes evident that the nominal In composition of 28% is reached at later instant of the AlInN growth process as compared to Al. This leads to a 0.4 nm thick In-depleted phase at the initial stage of growth accompanied by a slight spreading of Ga beyond the interface with no auto-incorporation into the bulk AlInN. These observations are consistent with X-ray diffraction studies on c-plane AlInN/GaN super lattice structures. We conclude the intrinsic tendency of AlInN to form an Al-rich phase in the early stage of growth independent of the crystal orientation. We thank FEI for providing HAADF and EDS data.