[1Hp01-06] Semiconductor/Magnetic, Electronic, and Photonic devices/Electronic Material Processing (SE/TF/EMP/MI/MS)

[1Hp02] Effect of interface between neodymium fluoride thin film and oxide or fluoride substrate on vacuum ultraviolet photoconductivity

*Gakuto Ozawa¹, Yusuke Horiuchi¹, Tomoki Kato¹, Marilou Cadatal-Raduban^2,3, Shingo ONO¹ (1. Department of Physical Science and Engineering, Nagoya Institute of Technology, 2. Centre for Theoretical Chemistry and Physics, School of Natural Sciences, Massey University, 3. Institute of Laser Engineering, Osaka University)

We investigated the effect of annealing on the characteristics of neodymium trifluoride (NdF₃) thin film/quartz (SiO₂) substrate interface and NdF₃ photoconductivity within the VUV. Thin films are deposited on unheated and heated (600^oC) substrates with post deposition annealing. Dark current of films on unheated substrates decreases by as much as 1/10 as resistance increases from 1 TW-12 TW after annealing. Dark current of films on heated substrates increases even after annealing, resulting to similar photo and dark currents of ~303.7 nA and poor detectors. Fluorine diffuses from the film to the substrate during deposition, exacerbated by substrate heating but not by annealing. Fluorine diffusion degrades crystallinity near the interface, increasing the dark current. Fluorine diffusion is absent when MgF₂ is used as the heated substrate. Considering the film/substrate interface and annealing is crucial when developing VUV photodetectors.