Growth of GaN nanowires by direct reaction of Ga with NH3

Semiconducting. single crystal wurtzite GaN nanowires have been grown by direct reaction of metal Ga with NH3 in a tube furnace. This paper discusses the growth mechanism. Nanowires grow only between 825 degreesC and 925 degreesC. Their diameters vary between 20 and 150 nm and depend directly on temperature and NH3 flow rate. Wires as long as 500 mum have been fabricated; once wires have formed, their length increases directly with time in the reactor. There are three different stages in the process, each of which has its own mechanism, First. a nearly amorphous GaN matrix forms, followed by growth of hillocks of thin GaN platelets. Finally, nanowires emerge from the edges of the platelets in characteristic directions, This analysis can be used as a guide for controlling GaN wire diameters and lengths. Strategies for growth of thinner and thicker nanowires are suggested. Thicker cylindrical structures denoted as rods grow from the face of the platelets. Description of their growth mechanism requires further study. (C) 2001 Elsevier Science BN. All rights reserved.