Ultrafast Infrared Photoresponse from Heavily Hydrogen-Doped VO₂ Single Crystalline Nanoparticles

Infrared photodetectors are sought for diverse applications and their performance relies on photoactive materials and photocurrent generation mechanisms. Here, we fabricate IR photodetectors with heavily hydrogen-doped VO₂ (i.e., HVO₂) single-crystalline nanoparticles which show two orders greater resistivities than pure VO₂. The I-V plots obtained under IR light irradiation are expressed by space charge limited current mechanism and the increase in photocurrent occurs due to the increase in the number of photoinduced trap sites. This phenomenon remarkably improves the key parameters at λ = 780 nm of high responsivity of 35280 A/W, high detectivity of 1.12 × 10¹³ Jones, and strikingly fast response times of 0.6-2.5 ns, that is, 3 orders of magnitude faster than the best records of two-dimensional structures and heterostructures. Density functional theory calculations illustrate that the generation of photoinduced trap sites is attributed to the movement of hydrogen atoms to less stable interstitial sites in VO₂ under light exposure.