Groups III-V semiconductor materials have been shown to be superior to silicon for particular applications, including, for example, optoelectronic applications. In such applications, a layer of a Group III-V material may be grown over a semiconductor substrate in a pillar shape, with a narrow diameter and a height which is sufficiently long compared the diameter. When the diameter of the Group III-V material is narrowed to a few tens of nanometers, the resultant structure may be referred to as a “nanowire.”