Plasma assisted molecular beam epitaxy of GaN with growth retes > 2.6 μm/h

Plasma assisted molecular beam epitaxial (PAMBE) growth of gallium nitride (GaN) was explored with a novel modification of a commercially available nitrogen plasma source. The modified nitrogen plasma source enabled a dramatic increase in the flux of active nitrogen and thus a significantly higher growth rate than has been previously reported. GaN films were grown using N-2 gas flow rates between 1 and 8 seem while varying the plasma source's RF forward power from 200 to 600W. The highest growth rate, and therefore the highest active nitrogen flux achieved was similar to 2.65 mu m/h. For optimized growth conditions the surfaces displayed a clear step-terrace structure with an average RMS roughness (3 mu m x 3 mu m) On the order of 1 nm Secondary ion mass spectroscopy (SlMS) impurity analysis demonstrates oxygen and hydrogen incorporation of 1 x 10(16) and 5 x 10(16) respectively, comparable to the metal organic chemical vapor deposition (MOCVD) grown template layer. Initial un-optimized electron mobility measurements of 1 pin thick GaN layers have shown a peak mobility of similar to 705 cm(2)/V s for an electron concentration of similar to 3.5 x 10(16) cm(-3). A revised universal growth diagram is proposed allowing the rapid determination of the metal flux needed to grow in a specific growth regime for any and all active nitrogen fluxes available. (C) 2013 Elsevier B.V. All rights reserved