Impact of silicon substrate on micro gas chromatographic column using ALD alumina as the stationary phase.

Abstract

Due to the high conformal films, atomic layer deposition (ALD) alumina has been used as a uniform stationary phase or support layer of stationary phase for micro gas chromatographic column. However, the severe tailing of chromatographic peaks appears when ALD alumina is used as the stationary phase. Recently, an H-diffusion model was proposed to explain the H accumulation phenomenon of ALD alumina films. Compared with the normal-resistance silicon substrates, the ALD alumina films based on low-resistance silicon substrates have fewer H impurities, which may further improve the tailing of chromatographic peaks and the theoretical number of plates. In this paper, a micro gas chromatographic column based on the low-resistance silicon (LR-μGCC) substrate (resistivity, 0.001-0.005 Ω·cm) using alumina deposited by atomic layer deposition as the stationary phase is reported. Compared with normal-resistance silicon substrates (resistivity, 1-10 Ω·cm), the micro gas chromatographic columns (μGCC) prepared on low-resistance silicon substrates have a higher separation performance. The test results showed that the LR-μGCC increased the theoretical plate number of alkane mixtures (n-hexane, n-octane, n-nonane, and n-decane) by 20.9%, 74.8%, 139.4%, and 55.4%, respectively, and reduced the tailing factor by 13.0%, 41.8%, 48.6%, and 49.1%, respectively.