Understanding of the mechanism of pulsed NH3 growth in metalorganic chemical vapor deposition.

We have studied the mechanism of pulsed NH 3 growth in metalorganic chemical vapor deposition by investigating the influence of interruption duration of NH 3 , growth temperature, pressure and NH 3 flow rate on the growth behavior of GaN selective area growth (SAG). The essential mechanism of pulsed NH 3 is to create a short-term metal-rich growth condition, thus facilitating the growth of { 1 0 1 ¯ 1 } facets. Optimized pulse duration, growth temperature, pressure and NH 3 flow rate balance the amount of Ga atoms on the surface and create an appropriate metal-rich condition, resulting in an enhanced lateral growth rate by dramatically increasing the growth rate of { 1 0 1 ¯ 1 } facet. We have achieved hexagonal GaN plates with flat c -plane top surfaces and { 1 0 1 ¯ 0 } vertical sidewalls on substrates with a fill factor of about 0.1%. The understanding of pulsed NH 3 growth technique will significantly promote the preparation of crystals by SAG or epitaxial lateral overgrowth, especially on substrates with a very low fill factor. [ABSTRACT FROM AUTHOR]