Toward deeper ultraviolet detection: Atomic layer deposited amorphous AlGaOx thin film detector with its tunable optical properties and opto-electronic responses

• Published in: Ceramics international 2024-06, Vol.50 (11), p.19856-19863
• Main Authors: Liu, Weiming, Zhu, Xudan, Ding, Yifan, Tang, Hongyu, Xu, Peiran, Huang, Tiantian, Zheng, Yuxiang, Chen, Xin, Zhang, Rongjun
• Format: Article
• Language: English
• Subjects: AlGaOx; Atomic layer deposition; Optical properties; Solar-blind UV detection
• ISSN: 0272-8842; 1873-3956
• DOI: 10.1016/j.ceramint.2024.03.110

Employing atomic layer deposition, AlGaOx films with varying Al concentrations (highest to 44% at.) were meticulously synthesized. Comprehensive characterization encompassing chemical composition, elemental depth distribution, structural clarity, and interface delineation unequivocally attested to the superior quality of the films. Optical properties were rigorously assessed using transmittance spectra and spectroscopic ellipsometry (SE), and optical constants across a broad spectral range (200–1000 nm) were determined through SE fitting. A consistent blue-shift in the absorption edge, observed in both the transmittance spectra and extinction coefficient, is attributed to the incorporation of aluminum. Detailed exploration via X-ray photoelectron spectroscopy fine scans of O 1s energy loss spectra and valence band analysis revealed that the evolution of the conduction band is instrumental in modulating the bandgap. To ascertain the viability for deep ultraviolet light detection, photodetectors based on AlGaOx were fabricated. Blue shifts in both photocurrent and response peak wavelength correlated with increasing Al content. In specific occasions, the AlGaOx-based detector has a responsibility of 0.05 A/W and 7×1013 detectivity of Jones. Remarkably, the detector demonstrates commendable on/off capability, characterized by fast rise and decay times of 0.26 s and 0.17 s, respectively. This study extensively examined the chemical, structural, and optical properties of amorphous AlGaOx films, alongside the optoelectronic capabilities of AlGaOx-based devices. Our research presented a viable strategy for enhanced deep ultraviolet detection, showcasing a successful implementation of amorphous bandgap engineering. This endeavor holds promise for future advancements in UV-detector development. AGO films with varying aluminum concentrations were synthesized via atomic layer deposition. Notably, with increasing aluminum concentration, the responsivity peak displayed a blue shift tendency, corresponding to the movement of the absorption edge. The substantial variation in AGO film bandgap values primarily stemmed from the upward shift in conduction band minimum. [Display omitted] •AlGaOx films were prepared through atomic layer deposition with Al content up to 44% at.•The optical properties were studied by spectroscopic ellipsometry and transmission spectrum.•With higher Al concentration, the bandgap of AlGaOx films increases.•AlGaOx-based detectors were fabricated wit