Planar hybrid UV-C photodetectors based on aerosol-jet printed PEDOT:PSS on different Ga2O3 thin films

Abstract

Ultra-wide bandgap semiconductors like Ga₂O₃, presenting intrinsic spectral selectivity in the UV-C region of the electromagnetic spectrum, are especially well suited for application as solar-blind photodetectors. In this work, photodiodes based on a planar hybrid heterojunction between Ga₂O₃ and an organic semiconductor are fabricated.

Specifically, the photodetectors consist of layers of nominally undoped β-Ga₂O₃, κ-Ga₂O₃, amorphous Ga₂O₃ or Si-doped κ-Ga₂O₃ over which an ink based on heavily doped PEDOT:PSS is directly deposited by aerosol-jet printing. Optimization of the latter process is pursued, ensuring the minimization of overspray and ill-defined features over all the tested layers, especially on the amorphous one, which was found to be the most compatible with this deposition technique.

After characterization of the fabricated devices electrical and optoelectronic properties, β-Ga₂O₃ presents the best lower-bound estimate values of peak responsivity, external quantum efficiency, and a specific detectivity of 4.5⋅10⁻² A/W, 23 % and 3.2⋅10¹² Jones respectively, at a wavelength (λ) of 240 nm, along with a UV-C/visible (λ = 240/400 nm) rejection ratio of 1.6·10³. However, as the sputtering deposition process is scalable and inexpensive compared to epitaxial crystal growth, amorphous Ga₂O₃ emerges as a cost-effective alternative to β-Ga₂O₃ for solar-blind photodetection.