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Reduction of carbon impurities in aluminium nitride from time-resolved chemical vapour deposition using trimethylaluminum

preprint
revised on 08.05.2020 and posted on 11.05.2020 by Polla Rouf, Pitsiri Sukkaew, Lars Ojamäe, Henrik Pedersen

Aluminium nitride (AlN) is a semiconductor with a wide range of applications from light emitting diodes to high frequency transistors. Electronic grade AlN is routinely deposited at 1000 °C by chemical vapour deposition (CVD) using trimethylaluminium (TMA) and NH3 while low temperature CVD routes to high quality AlN are scarce and suffer from high levels of carbon impurities in the film. We report on an ALD-like CVD approach with time-resolved precursor supply where thermally induced desorption of methyl groups from the AlN surface is enhanced by the addition of an extra pulse, H2, N2 or Ar between the TMA and NH3 pulses. The enhanced desorption allowed deposition of AlN films with carbon content of 1 at. % at 480 °C. Kinetic- and quantum chemical modelling suggest that the extra pulse between TMA and NH3 prevents re-adsorption of desorbing methyl groups terminating the AlN surface after the TMA pulse.

Funding

This project was supported by the Swedish Foundation for Strategic Research (SSF) through the project “Time-resolved low temperature CVD for III-nitrides” (SSF-RMA 15-0018). LO acknowledges financial support from the Swedish Government Strategic Research Area in Materials Science on Functional Materials at Linköping University (Faculty Grant SFO Mat LiU no. 2009 00971) and from the Swedish Research Council (VR). Supercomputing resources were provided by the Swedish National Supercomputer Centre (NSC) via the Swedish National Infrastructure for Computing (SNIC).

History

Email Address of Submitting Author

henrik.pedersen@liu.se

Institution

Linkoping University

Country

Sweden

ORCID For Submitting Author

0000-0002-7171-5383

Declaration of Conflict of Interest

No conflicts to declare

Licence

Exports