Freestanding Oxide-Based UV Photodetectors with Mechanically Tunable Performance

Area of Science:

• Materials Science
• Nanotechnology
• Optoelectronics

Background:

• Schottky junction ultraviolet (UV) detectors offer high detectivity and low noise.
• Enhancing Schottky barrier height (SBH) is crucial for improving UV detector performance by reducing dark current.
• Flexoelectricity is a promising strategy for SBH modulation, but its application in oxide devices is hindered by substrate constraints.

Purpose of the Study:

• To demonstrate a freestanding ZnO Schottky photodetector for enhanced UV detection.
• To investigate the modulation of SBH using electromechanical coupling (piezoelectric and flexoelectric effects).
• To explore strain engineering in freestanding oxide semiconductors for mechanically tunable UV photodetectors.

Main Methods:

• Fabrication of a freestanding ZnO Schottky photodetector.
• Application of mechanical force to modulate the Schottky barrier height (SBH).
• Characterization of UV detection performance, including responsivity and detectivity, under varying strain conditions.

Main Results:

• The Schottky barrier height (SBH) was successfully elevated from 0.48 to 0.57 V with increasing applied force.
• Device responsivity significantly increased from 10 mA·W^-1 to 678 mA·W^-1.
• Detectivity showed a substantial enhancement, rising from 3.7 × 10⁹ Jones to 7.9 × 10¹¹ Jones.

Conclusions:

• Freestanding ZnO Schottky photodetectors enable mechanical tuning of SBH via electromechanical coupling.
• Strain engineering in freestanding oxide semiconductors is a viable approach for high-performance UV detection.
• This work highlights the potential for developing mechanically tunable, high-performance UV photodetectors.