Enhancing the field emission properties of Se-doped GaN nanowires

Pure and Se-doped GaN nanowires (NWs) are synthesized on Pt-coated Si(111) substrates via chemical vapor deposition. The GaN NWs exhibit a uniform density with an average diameter of 20-120 nm. The structure of the NWs is wurtzite hexagonal, and the growth direction is along [ 0001]. Field emission measurements show that the Se-doped GaN NWs possess a low turn-on field (2.9 V mu m(-1)) compared with the pure GaN NWs (7.0 V mu m(-1)). In addition, density functional theory calculations indicate that the donor states near the Fermi level are mainly formed through the hybridization between Se 4p and N 2p orbitals and that the Fermi level move towards the vacuum level. Consequently, the work functions of Se-doped GaN NWs are lower than those of pure GaN NWs.