In-Operando Optical Spectroscopy of Field-Effect-Gated Al-Doped ZnO.

Area of Science:

• Materials Science
• Condensed Matter Physics
• Photonics

Background:

• Transparent conductive oxides (TCOs) possess a unique combination of optical transparency and electrical conductivity.
• Their optical response is highly sensitive to doping levels, making them suitable for photonic applications.
• Aluminum-doped zinc oxide (AZO) is a TCO based on abundant elements.

Purpose of the Study:

• To investigate the active electrical manipulation of dielectric properties in aluminum-doped zinc oxide (AZO).
• To tune the optical and electrical performance of AZO films using an applied voltage.
• To understand the effect of charge injection and depletion on TCO behavior.

Main Methods:

• Fabrication of AZO films on SrTiO3 dielectric in a parallel-plate capacitor configuration.
• Applied voltage to electrically tune dielectric properties.
• In-operando spectroscopic ellipsometry to monitor changes in optical response.
• Optical response calculations to determine dielectric function variations and charge profiles.

Main Results:

• Successfully demonstrated active electrical tuning of optical and electric properties of AZO films.
• Observed significant sensitivity of the optical response to applied voltage, indicating modulation of dielectric properties.
• Extracted spatially resolved dielectric function variations and inferred charge injection/depletion profiles.

Conclusions:

• The study confirms the feasibility of electrical control over TCO dielectric properties.
• This electrical modulation of AZO offers a pathway for tunable photonic devices.
• The findings provide insights into charge dynamics at the TCO-dielectric interface.