Napari Mari, Huq Tahmida N, Meeth David J, Heikkilä Mikko J, Niang Kham M, Wang Han, Iivonen Tomi, Wang Haiyan, Leskelä Markku, Ritala Mikko, Flewitt Andrew J, Hoye Robert L Z, MacManus-Driscoll Judith L
Department of Materials Science and Metallurgy, University of Cambridge, Cambridge CB3 0FS, U.K.
Electrical Engineering Division, Department of Engineering, University of Cambridge, Cambridge CB3 0FA, U.K.
ACS Appl Mater Interfaces. 2021 Jan 27;13(3):4156-4164. doi: 10.1021/acsami.0c18915. Epub 2021 Jan 14.
High-performance p-type oxide thin film transistors (TFTs) have great potential for many semiconductor applications. However, these devices typically suffer from low hole mobility and high off-state currents. We fabricated p-type TFTs with a phase-pure polycrystalline CuO semiconductor channel grown by atomic layer deposition (ALD). The TFT switching characteristics were improved by applying a thin ALD AlO passivation layer on the CuO channel, followed by vacuum annealing at 300 °C. Detailed characterization by transmission electron microscopy-energy dispersive X-ray analysis and X-ray photoelectron spectroscopy shows that the surface of CuO is reduced following AlO deposition and indicates the formation of a 1-2 nm thick CuAlO interfacial layer. This, together with field-effect passivation caused by the high negative fixed charge of the ALD AlO, leads to an improvement in the TFT performance by reducing the density of deep trap states as well as by reducing the accumulation of electrons in the semiconducting layer in the device off-state.
高性能p型氧化物薄膜晶体管（TFT）在许多半导体应用中具有巨大潜力。然而，这些器件通常存在空穴迁移率低和关态电流高的问题。我们通过原子层沉积（ALD）生长了具有相纯多晶CuO半导体沟道的p型TFT。通过在CuO沟道上施加一层薄的ALD AlO钝化层，然后在300°C下进行真空退火，改善了TFT的开关特性。通过透射电子显微镜-能量色散X射线分析和X射线光电子能谱进行的详细表征表明，在AlO沉积后CuO表面被还原，并表明形成了1-2nm厚的CuAlO界面层。这与由ALD AlO的高负固定电荷引起的场效应钝化一起，通过降低深陷阱态密度以及减少器件关态下半导体层中电子的积累，导致TFT性能得到改善。
