• Menzel, D.; Korte, L.: Evolution of Optical, Electrical, and Structural Properties of Indium Tungsten Oxide upon High Temperature Annealing. Physica Status Solidi A 218 (2020), p. 2000165/1-8

10.1002/pssa.202000165
Open Access Version (externer Anbieter)

Abstract:
Optical, structural and electrical properties of thermally co-evaporated indium tungsten oxide (IWOx) thin films with varied stoichiometry, from pure tungsten oxide to pure indium oxide (InOx) are investigated upon stepwise annealing, up to 700°C. The thin films are candidate materials for carrier selective contacts in different types of solar cells, such as silicon hetero junction and perovskite solar cells. We find three different phases for the thin films with different stoichiometry and crystallization temperatures of Tc>500°C for tungsten-rich layers and Tc approximately 200°C for indium-rich layers. The pronounced optical absorption of the as-deposited InOx-rich layers is strongly decreased after crystallization. Tungsten oxide rich layers show low optical absorption in the as-deposited state as well as for all applied annealing temperatures. The lateral conductivity of the pure indium oxide could be increased from 1.24*10^(-2) S/cm up to 0.83 S/cm after 700°C annealing. The conductivity of the pure tungsten oxide increased slightly after crystallization from 2.55*10^(-5) S/cm to 8.25*10^(-5) S/cm after annealing at 700°C. However, for mixed oxide layers with approximately 25% InOx-fraction in the mixture the highest conductivity of 4.0*10^(-6) S/cm could not be increased by the applied annealing process.