Abstract
The growth of single‐crystal epitaxial layers of 
onto (0001) oriented sapphire substrates from the liquid phase is shown to require three conditions:(i) the partial pressure of 
in the H2 ambient, 
greater than the equilibrium pressure, (ii) the growth melt positioned in a thermal gradient to transport the dissolved 
to the growth interface, and (iii) the control of nucleation by the addition of Bi to the growth melt. Studies of growth at temperatures from 850° to 1050°C show that the layer thickness, 
, is approximately linear in time and varies with growth temperature and atom fraction of Ga, 
in the growth melt. When 
, internal cracks in the 
basal plane hexagonal directions develop at the layer‐substrate interface and for 
they propagate to the surface and are thermally etched. A description is given of the interaction of liquid Ga with 
as a function of 
and 
. The low solubility of 
in Ga (
fraction at 1150°C) prevents useful growth by slow cooling of the melt. The inability to change the electron concentration, 
, with Zn doping and the decrease of 
with 
in the growth melt support but do not unambiguously confirm the model that the native donor is a nitrogen vacancy