Xiao, T.; Erfurt, D.; Félix, R.; Liao, X.; Frisch, J.; Abou-Ras, D.; Mazzio, K.A.; Wilks, R.G.; Schlatmann, R.; Bär, M.: Annealing-Induced Chemical Interaction at the Ag/In2O3:H Interface as Revealed by In Situ Photoelectron Spectroscopy. Advanced Materials Interfaces 10 (2023), p. 2202347/1-8
10.1002/admi.202202347
Open Access Version
Abstract:
Hydrogen-doped In2O3 (In2O3:H) is highly conductive while maintaining extraordinary transparency, thus making it a very attractive material for applications in optoelectronic devices such as (multijunction) solar cells or light-emitting devices. However, the corresponding metal/In2O3:H contacts may exhibit undesirably high resistances, significantly deteriorating device performance. To gain insight into the underlying efficiency-limiting mechanism, hard X-ray photoelectron spectroscopy is employed to in-situ monitor annealing-induced changes in the chemical structure of the Ag/In2O3:H interface system that is further complemented by ex-situ electron microscopy analyses and contact resistance measurements. The observed evolution of the Ag- and In-related photoelectron line intensities can be explained by significant intermixing across the Ag/In2O3:H interface. The corresponding lineshape broadening of the Ag 3d spectra is attributed to the formation of Ag2O and AgO, which becomes significant at temperatures above approximately 160 °C. However, after annealing to 300 °C, instead of the formation of an insulating AgOx interfacial layer, it is found i) In to be rather homogeneously distributed in the complete Ag/In2O3:H stack, ii) Ag diffusing into the In2O3:H, and iii) an improvement of the contact resistance rather than its often-reported deterioration.