Berlin 2015 – wissenschaftliches Programm

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HL: Fachverband Halbleiterphysik

HL 40: Focus Session: Role of polarization fields in nitride devices I

HL 40.2: Vortrag

Mittwoch, 18. März 2015, 10:00–10:15, ER 164

Composition of lattice-matched AlInN at the early stage of growth — •Philipp Horenburg¹, Uwe Rossow¹, Ernst Ronald Buss¹, Heiko Bremers¹, Daniel Henzler², Felix Schwarzhuber², Josef Zweck², and Andreas Hangleiter¹ — ¹Institute of Applied Physics, TU Braunschweig, Germany — ²Institute of Experimental and Applied Physics, University of Regensburg, Germany

With a nominal indium content of about 18%, Al_1-xIn_xN is a-lattice matched to GaN. As compared to Al_1-xGa_xN, lattice-matched Al_1-xIn_xN has a higher contrast in refractive index to GaN. These advantageous properties make AlInN a promising material for Bragg-reflectors and cladding layers in optical devices. However, the epitaxy of lattice matched AlInN is a complex task due to the very different ideal growth conditions of AlN and InN. In this contribution, we will show that the effective In content of thin AlInN layers depends on their thickness. A series of tenfold superlattice structures with varying thickness of the AlInN layers and GaN interlayers of approximately 1 nm was grown by low-pressure MOVPE. Assuming a ternary AlInN layer, our observations suggest the formation of an indium depleted phase at the initial stage of growth. On the other hand, TEM-EDX measurements on AlInN single layers hint at parasitic gallium incorporation in the first few nanometers in AlInN growth, which can be misinterpreted assuming ternary layers. Parasitic Ga in the AlInN would also lead to an overestimation of the Al content assuming ternary AlInN layers in simulation of XRD-profiles.