Iancu Andrei T, Logar Manca, Park Joonsuk, Prinz Fritz B
Department of Mechanical Engineering, Stanford University , Stanford, California 94305, United States.
ACS Appl Mater Interfaces. 2015 Mar 11;7(9):5134-40. doi: 10.1021/am5072223. Epub 2015 Jan 25.
With prominent photocatalytic applications and widespread use in semiconductor devices, TiO2 is one of the most popular metal oxides. However, despite its popularity, it has yet to achieve its full potential due to a lack of effective methods for achieving p-type conductivity. Here, we show that undoped p-type TiO2 films can be fabricated by atomic layer deposition (ALD) and that their electrical properties can be controlled across a wide range using proper postprocessing anneals in various ambient environments. Hole mobilities larger than 400 cm(2)/(V·s) are accessible superseding the use of extrinsic doping, which generally produces orders of magnitude smaller values. Through a combination of analyses and experiments, we provide evidence that this behavior is primarily due to an excess of oxygen in the films. This discovery enables entirely new categories of TiO2 devices and applications, and unlocks the potential to improve existing ones. TiO2 homojunction diodes fabricated completely by ALD are developed as a demonstration of the utility of these techniques and shown to exhibit useful rectifying characteristics even with minimal processing refinement.
由于在光催化应用方面表现突出且在半导体器件中广泛使用，二氧化钛（TiO₂）是最受欢迎的金属氧化物之一。然而，尽管它很受欢迎，但由于缺乏实现p型导电性的有效方法，它尚未充分发挥其潜力。在此，我们表明未掺杂的p型TiO₂薄膜可以通过原子层沉积（ALD）制备，并且通过在各种环境中进行适当的后处理退火，可以在很宽的范围内控制其电学性能。无需使用通常会产生小几个数量级值的非本征掺杂，就能获得大于400 cm²/(V·s) 的空穴迁移率。通过分析与实验相结合，我们提供证据表明这种行为主要是由于薄膜中存在过量的氧。这一发现开启了全新类别的TiO₂器件和应用，并为改进现有器件和应用释放了潜力。通过ALD完全制备的TiO₂同质结二极管被开发出来，以证明这些技术的实用性，并且即使经过最少的工艺优化，也显示出有用的整流特性。
