<p>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 NH<sub>3</sub> 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, H<sub>2</sub>, N<sub>2</sub> or Ar between the TMA
and NH<sub>3</sub> 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 NH<sub>3</sub>
prevents re-adsorption of desorbing methyl groups terminating the AlN surface after
the TMA pulse. </p>
