Kemelbay Aidar, Tikhonov Alexander, Aloni Shaul, Kuykendall Tevye R
School of Science and Technology, Nazarbayev University, 010000 Nur-Sultan, Kazakhstan.
The Molecular Foundry, Lawrence Berkeley National Laboratory, Berkeley, CA 94720, USA.
Nanomaterials (Basel). 2019 Jul 28;9(8):1085. doi: 10.3390/nano9081085.
As one of the highest mobility semiconductor materials, carbon nanotubes (CNTs) have been extensively studied for use in field effect transistors (FETs). To fabricate surround-gate FETs- which offer the best switching performance-deposition of conformal, weakly-interacting dielectric layers is necessary. This is challenging due to the chemically inert surface of CNTs and a lack of nucleation sites-especially for defect-free CNTs. As a result, a technique that enables integration of uniform high-k dielectrics, while preserving the CNT's exceptional properties is required. In this work, we show a method that enables conformal atomic layer deposition (ALD) of high-k dielectrics on defect-free CNTs. By depositing a thin Ti metal film, followed by oxidation to TiO under ambient conditions, a nucleation layer is formed for subsequent ALD deposition of AlO. The technique is easy to implement and is VLSI-compatible. We show that the ALD coatings are uniform, continuous and conformal, and Raman spectroscopy reveals that the technique does not induce defects in the CNT. The resulting bilayer TiO/AlO thin-film shows an improved dielectric constant of 21.7 and an equivalent oxide thickness of 2.7 nm. The electrical properties of back-gated and top-gated devices fabricated using this method are presented.
作为迁移率最高的半导体材料之一，碳纳米管（CNTs）已被广泛研究用于场效应晶体管（FETs）。为了制造具有最佳开关性能的环绕栅FET，需要沉积保形且弱相互作用的介电层。由于碳纳米管的化学惰性表面和成核位点的缺乏，这具有挑战性，尤其是对于无缺陷的碳纳米管。因此，需要一种能够集成均匀高k电介质同时保留碳纳米管优异性能的技术。在这项工作中，我们展示了一种在无缺陷碳纳米管上实现高k电介质保形原子层沉积（ALD）的方法。通过沉积一层薄的钛金属膜，然后在环境条件下氧化成TiO，形成一个成核层，用于随后的AlO的ALD沉积。该技术易于实施且与超大规模集成电路兼容。我们表明，ALD涂层是均匀、连续且保形的，拉曼光谱显示该技术不会在碳纳米管中引入缺陷。所得的TiO/AlO双层薄膜显示出21.7的改进介电常数和2.7nm的等效氧化层厚度。本文还介绍了使用该方法制造的背栅和顶栅器件的电学性能。
