Substrate reactivity as the origin of Fermi level pinning at the Cu2O/ALD-Al2O3 interface

作者：Deuermeier Jonas^*; Bayer Thorsten J M; Yanagi Hiroshi; Kiazadeh Asal; Martins Rodrigo; Klein Andreas; Fortunato Elvira

来源：Materials Research Express, 2016, 3(4): 046404.

DOI：10.1088/2053-1591/3/4/046404

• Cu2O
• Al2O3
• x-ray photoelectron spectroscopy (XPS)
• atomic layer deposition (ALD)
• magnetron sputtering
• Fermi level pinning
• Schottky barrier

The reduction of a Cu2O layer on copper by exposure to TMA during the atomic layer deposition of Al2O3 has recently been reported. (Gharachorlou et al 2015 ACS Appl. Mater. Interfaces 7 1642816439). The study presented here analyzes a similar process, leading to the reduction of a homogeneous Cu2O thin film, which allows for additional observations. Angle-resolved in situ x-ray photoelectron spectroscopy confirms the localization of metallic copper at the interface. The evaluation of binding energy shifts reveals the formation of aCu(2)O/Cu Schottky barrier, which gives rise to Fermi level pinning in Cu2O. An initial enhancement of the ALD growth per cycle (GPC) is only observed for bulk Cu2O samples and is thus related to lattice oxygen, originating from regions lying deeper than just the first few layers of the surface. The oxygen out-take from the substrate is limited to the first few cycles, which is found to be due to a saturated copper reduction, rather than the oxygen diffusion barrier of Al2O3.

• 出版日期2016-4