High performance UV photodetectors based on W doped δ -Ta2O5 single crystalline films

Abstract

Amorphous or polycrystalline tantalum pentoxide (Ta2O5) films with high resistance have been widely used in semiconductor devices as insulating dielectric layers. In this work, tungsten (W) doped δ-Ta2O5 (0001) monocrystal films were deposited on Y-stabilized ZrO2 (111) substrates using a pulsed laser deposition system. The lattice structure, heteroepitaxial relationship, and electrical properties of the films were analyzed in detail. The carrier concentration, Hall mobility, and resistivity of the 2% W doped δ-Ta2O5 film are 6.61 × 1015 cm−3, 65.2 cm2/V s and 14.5 Ω cm, respectively. High performance metal–semiconductors–metal ultraviolet (UV) detectors based on the W doped δ-Ta2O5 films were fabricated. The UV detector based on a 2% W doped δ-Ta2O5 film exhibits a high photo responsivity of 10.32 A/W and a photocurrent-to-darkcurrent ratio of 1.3 × 104. The performances of the UV detectors in this work are so high, which indicates that the W doped δ-Ta2O5 films can be applied in UV detectors as an active layer.