Electrical transport in GaN nanowires grown by selective epitaxy

The authors report on the electrical transport characteristics of undoped, n -doped, and pn -junction GaN nanowires grown by selective epitaxy on GaN/sapphire substrates. The selective epitaxy is realized by a combination of a patterned Si 3 N 4 mask, which defines the position and diameter of the nanowires, and appropriate growth conditions, which lead to a near one-dimensional growth along the c -direction. They find that the electrical transport in nominally undoped nanowires is dominated by space charge limited conduction, and using a new theory for space charge limited conduction, they extract an electron mobility of ∼400 cm 2 /V s and a free carrier concentration of ∼ 10 15 - 10 16 cm -3. By controlling the nanowire doping, they observe Ohmic transport for n -doped nanowires and rectifying characteristics for pn -junction nanowires. © 2009 American Vacuum Society.