A thermodynamic analysis of the generation of gaseous aluminum chlorides by the reaction between aluminum (Al) metal and hydrogen chloride (HCl) gas is described for hydride vapor phase epitaxy (HVPE) of AlN. Regardless of the hydrogen mole fraction in the carrier gas, the major species of aluminum chloride is AlCl when the temperature of the Al metal is above 790 °C and is AlCl 3 when the temperature is below 790 °C. Since AlCl 3 is less reactive with quartz (SiO 2 ) than AlCl, HVPE of AlN is possible using AlCl 3 and NH 3 even with a conventional system having a quartz reactor. Successful AlN HVPE on sapphire substrates is also reported.

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Growth of thick AlN layer was performed directly on sapphire (0001) substrate at 1100 ºC by hydride vapor phase epitaxy (HVPE) using AlCl 3 and NH 3 as source gases. Growth rate over 10 µm/h was demonstrated by increasing input partial pressure of AlCl 3 . Also, it was found that the growth rate was sensitive to NH 3 input partial pressure ( o NH 3 P ), and decreased rapidly with increase of o NH 3 P . Edge dislocation density estimated from full width at half maximum (FWHM) of X-ray diffraction (XRD) rocking curves was independent of the growth rate.