Preparation of highly-ordered lanthanum hexaboride nanotube arrays and optimizing its field emission property by ion bombardment post-treatment

Abstract

Large scale, highly-ordered and vertically aligned lanthanum hexaboride (LaB6) nanotube arrays were prepared by DC magnetron sputtering deposition LaB6 on ultra-thin anodic aluminum oxide (AAO) substrates. The LaB6 nanotube arrays that were 210 nm in diameter and 620 nm in height haven’t collapsed and aggregated after the AAO templates have been removed by wet etching. After that, LaB6 nanotube arrays were bombarded by low energy Ar ion, which was used to further optimize its field emission property. X-ray diffraction measurement shows that LaB6 nanotube arrays are uniform polycrystalline phase without preferred orientation. SEM analysis shows that ion bombardment is an effective method for adjusting the micro-morphology of nanotube arrays. The cap-end nanotube arrays are turned into open-end, and the B/La atoms on its surface are decreased after ion bombardment. The formation of the open-end nanotube arrays with sharp edges and the enrichment of La atoms on the surface play an important role in enhancing the field emission property. The open-ended LaB6 nanotube arrays with sharp edges have the lowest turn-on field (6.8 V µm−1) and the highest current density (2.3 mA cm−2 at 11 V µm−1).