Department of Energy Systems Research & Department of Materials Science and Engineering, Ajou University , Suwon 16499, Republic of Korea.
Gyeongbuk Science Technology Promotion Center, Gumi Electronics & Information Technology Research Institute , Gumi 39171, Republic of Korea.
ACS Nano. 2017 Jun 27;11(6):6040-6047. doi: 10.1021/acsnano.7b01964. Epub 2017 May 22.
The tuning of electrical properties in oxides via surface and interfacial two-dimensional electron gas (2DEG) channels is of great interest, as they reveal the extraordinary transition from insulating or semiconducting characteristics to metallic conduction or superconductivity enabled by the ballistic transport of spatially confined electrons. However, realizing the practical aspects of this exotic phenomenon toward short-range ordered and air-stable 2DEG channels remains a great challenge. At the heterointerface formed after deposition of an AlO layer on a nanocrystalline InO layer, a dramatic improvement in carrier conduction equivalent to metallic conduction is obtained. A conductivity increase by a factor of 10 times that in raw InO, a sheet resistance of 850 Ω/cm, and a room temperature Hall mobility of 20.5 cm V s are obtained, which are impossible to achieve by tuning each layer individually. The physicochemical origin of metallic conduction is mainly ascribed to the 2D interfacially confined O-vacancies and semimetallic nanocrystalline InO (x < 2) phases by the clustered self-doping effect caused by O-extraction from InO to the AlO phase during ALD. Unlike other submetallic oxides, this 2D channel is air-stable by complete AlO passivation and thereby promises applicability for implementation in devices.
通过表面和界面二维电子气（2DEG）通道来调整氧化物的电学性质是非常有趣的，因为它们揭示了一种非凡的转变，即通过空间限制电子的弹道输运，使绝缘或半导体特性转变为金属导电性或超导性。然而，实现这种奇异现象的实际方面，即实现短程有序和空气稳定的 2DEG 通道，仍然是一个巨大的挑战。在将 AlO 层沉积在纳米晶 InO 层上形成的异质界面上，获得了载流子传导相当于金属传导的显著改善。与原始 InO 相比，电导率提高了 10 倍，比电阻为 850 Ω/cm，室温霍尔迁移率为 20.5 cm V s，这是通过单独调整每个层都不可能实现的。金属传导的物理化学起源主要归因于 2D 界面限制的 O 空位和半金属纳米晶 InO（x < 2）相，这是由 InO 中的 O 向 AlO 相提取引起的自掺杂效应引起的。与其他亚金属氧化物不同，这种 2D 通道通过完全的 AlO 钝化而稳定存在，因此有望在器件中得到应用。
