Regensburg 2010 – wissenschaftliches Programm

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O: Fachverband Oberflächenphysik

O 69: Symposium Polarization Field Control in Group-III-Nitrides

O 69.4: Hauptvortrag

Donnerstag, 25. März 2010, 11:15–11:45, H1

Molecular beam epitaxy as a method for the growth of free-standing zinc-blende GaN layers and substrates. — •Sergei Novikov, Thomas Foxon, and Anthony Kent — School of Physics and Astronomy, University of Nottingham, Nottingham, NG7 2RD, UK

The group III-nitrides normally crystallise in the hexagonal (wurtzite) structure. The unique feature of wurtzite group III-nitrides, in comparison with conventional III-V semiconductors, is the existence of very strong electric fields inside the crystal structure. The electric fields can be eliminated in wurtzite material by growing in non-polar directions. However, a direct way to eliminate electric fields would be to use non-polar (001) oriented zinc-blende (cubic) III-nitride layers. The thermodynamically metastable cubic GaN layers have, so far, received less attention than the more familiar hexagonal films.

We have developed a process for growth by molecular beam epitaxy (MBE) of free-standing cubic GaN layers with potential application as substrates. Undoped thick cubic GaN films were grown on semi-insulating GaAs (001) substrates by a modified plasma-assisted molecular beam epitaxy (PA-MBE) method and were removed from the GaAs substrate after the growth. The resulting free-standing GaN wafers with thickness in the 30-100μm range may be used as substrates for further epitaxy of cubic GaN-based structures and devices. We will discuss the fabrication and properties of cubic GaN substrates. The first GaN/InGaN LEDs on our zinc-blende GaN substrates have been demonstrated by our collaborators.