纳米厚度氮化硼薄膜的场发射特性

Field Emission Characteristics of BN Thin Films with Nanometer Thickness

利用射频磁控溅射方法,在n型(100)Si基底上沉积了不同厚度(54～135nm)的纳米氮化硼(BN)薄膜。红外光谱分析表明,BN薄膜结构为六角BN(h BN)相(1380cm-1和780cm-1)。在超高真空系统中测量了不同膜厚BN薄膜的场发射特性,发现BN薄膜的场发射特性与膜厚关系很大,阈值电场随着厚度的增加而增大。由于BN薄膜和Si基底界面间存在功函数差,使得Si基底中电子转移到BN薄膜的导带,在外电场作用下隧穿BN表面势垒,发射到真空。

Nanometer Boron Nitride(BN) thin films with various thickness(54～135nm) were prepared on the (100)oriented surface of nSi(0.008～0.02Ω·m) by r.f. magnetic sputtering physical vapor deposition(PVD). There were only two absorption peaks of hBN at about 1 380 cm-1 and 780 cm-1 by Fourier transform infrared spectra for the BN thin films. The field emission characteristics of thin BN films were measured in a super high vacuum system. It is found that the field emission characteristics of thin BN films depends evidently on the thickness of the films. The threshold voltage increases with the increase of the thickness in nanometer thickness range. This is attributed to the work function difference between BN thin film and Si substrate. Electrons are transferred from substrate Si to conduction band of BN thin film, and are emitted from BN to vacuum tunneling through the potential barrier at the surface of the BN thin film under exterior electric field action. 