Creation of a Short-Range Ordered Two-Dimensional Electron Gas Channel in Al2O3/In2O3 Interfaces
Creation of a Short-Range Ordered Two-Dimensional Electron Gas Channel in Al2O3/In2O3 Interfaces
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DOI：
10.1021/acsnano.7b01964
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发表时间：
2017-06-01
期刊：
影响因子：
17.1
通讯作者：
Seo, Hyungtak
中科院分区：
文献类型：
--
作者：
Lee, Sang Yeon;Kim, Jinseo;Seo, Hyungtak
通过表面和界面二维电子气(2DEG)通道来调节氧化物中的电学性质是非常有意义的，因为它们揭示了空间受限电子的弹道输运实现了从绝缘或半导体特性到金属导电或超导的非凡转变。然而，将这一奇异现象的实际方面应用于短距离有序和空气稳定的2DEG通道仍然是一个巨大的挑战。在纳米In_2O_3层上沉积Al_2O_3层后形成的异质界面上，载流子导电性得到了相当于金属导电性的显著改善。电导率提高了10(13)倍，方阻为850Omega/cm(2)，室温霍尔迁移率为20.5 cm(2)V~(-2)S(-2)，这是单独调谐各层所不能达到的。金属导电性的物理化学起源主要归因于在ALD过程中由In_2O_3向Al_2O_3相的团簇自掺杂效应导致的二维界面受限O-空位和半金属纳米晶InOx(x<；2)相。与其他亚金属氧化物不同的是，这种2D沟道是空气稳定的，通过完全的氧化铝钝化，从而保证了在器件中实施的适用性。
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 Al2O3 layer on a nanocrystalline In2O3 layer, a dramatic improvement in carrier conduction equivalent to metallic conduction is obtained. A conductivity increase by a factor of 10(13) times that in raw In2O3, a sheet resistance of 850 Omega/cm(2), and a room temperature Hall mobility of 20.5 cm(2) V-2 s(-2) 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 InOx (x < 2) phases by the clustered self-doping effect caused by O-extraction from In2O3 to the Al2O3 phase during ALD. Unlike other submetallic oxides, this 2D channel is air-stable by complete Al2O3 passivation and thereby promises applicability for implementation in devices.