%0 Journal Article
%T Effects of N2 Partial Pressure on Growth, Structure, and Optical Properties of GaN Nanorods Deposited by Liquid-Target Reactive Magnetron Sputter Epitaxy
%A Ching-Lien Hsiao
%A Jens Birch
%A Jun Lu
%A Justinas Palisaitis
%A Lars Hultman
%A Muhammad Junaid
%A Per Ola £¿ke Persson
%A Yen-Ting Chen
%J Archive of "Nanomaterials".
%D 2018
%R 10.3390/nano8040223
%X GaN nanorods, essentially free from crystal defects and exhibiting very sharp band-edge luminescence, have been grown by reactive direct-current magnetron sputter epitaxy onto Si (111) substrates at a low working pressure of 5 mTorr. Upon diluting the reactive N2 working gas with a small amount of Ar (0.5 mTorr), we observed an increase in the nanorod aspect ratio from 8 to ~35, a decrease in the average diameter from 74 to 35 nm, and a two-fold increase in nanorod density. With further dilution (Ar = 2.5 mTorr), the aspect ratio decreased to 14, while the diameter increased to 60 nm and the nanorod density increased to a maximum of 2.4 ¡Á 109 cm£¿2. Yet, lower N2 partial pressures eventually led to the growth of continuous GaN films. The observed morphological dependence on N2 partial pressure is explained by a change from N-rich to Ga-rich growth conditions, combined with reduced GaN-poisoning of the Ga-target as the N2 gas pressure is reduced. Nanorods grown at 2.5 mTorr N2 partial pressure exhibited a high intensity 4 K photoluminescence neutral donor bound exciton transitions (D0XA) peak at ~3.479 eV with a full-width-at-half-maximum of 1.7 meV. High-resolution transmission electron microscopy corroborated the excellent crystalline quality of the nanorods
%K GaN
%K nanorods
%K X-ray diffraction
%K TEM
%K photoluminescence
%K magnetron sputter epitaxy
%K sputtering
%U https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5923553/