Optical parameters and work function of Zn–In–Sn–O films

• The work function behavior of sputtered ZITO films were studied using Drude parameters and UPS.
• The Fermi level position changes of ZITO films do not affect the work function.
• The work function and ionization potential of ZITO follow similar behavior to the work function.
• The work function of ZITO may be linked to changes in ionization potential, not carrier concentration.

The work function behavior of Zn–In–Sn–O (ZITO) films with various Zn and Sn contents were studied. The work function increased with addition of Zn content. With further increase of Zn contents, the work function gradually decreased. The work function behavior can be investigated by (1) Fermi level position relative the carrier concentration, (2) ionization potential by the surface dipole change. The Fermi level position related the carrier concentration was calculated by Drude parameters, and ionization potential measured by UPS. As results, we confirmed that the work function of ZITO may be linked to changes in ionization potential, not carrier concentration.