Abstract
Abstract
We propose a simple approach to locally modify the conductance of molybdenum oxide thin films with thermal annealing in oxygen atmosphere at relatively low temperature for constructing a visible-blind ultraviolet photoconductor. The amorphous MoO
x
is grown by remote plasma enhanced atomic layer deposition (RPALD), and then crystallized into α-MoO
x
at 500 °C in argon atmosphere, which exhibits good conductance with resistivity of 3.9 × 10−3 Ω cm due to the formation of oxygen vacancies. Good ohmic contact between Ti and the crystallized MoO
x
is demonstrated with specific contact resistance of 9.74 × 10−4 Ω cm2. The lateral Au/Ti-MoO
x
-Ti/Au structures are defined and the conductance of the exposed MoO
x
channel is significantly modified by thermal annealing in oxygen atmosphere to form a photodetector, which shows obvious photoresponse at the wavelength of less than 372 nm with low dark current of 0.9 pA at 5 V, and the remarkable responsivity of 0.75 mA W−1 at 280 nm is achieved with a high ultravoilet/visible rejection ratio. The low dark current and incredible responsivity can be attributed to the good ohmic contacts of untreated MoO
x
and the reduction of number of oxygen vacancies in the MoO
x
channel. The key role of oxygen vacancy on the conductance of MoO
x
has been demonstrated. Those results suggest that the MoO
x
thin films are promising candidate for visible-blind ultraviolet photodetectors in a simple complementary metal oxide semiconductor (CMOS)-compatible process.
Funder
National Natural Science Foundation of China
National Key Research Program of China
Subject
Surfaces, Coatings and Films,Acoustics and Ultrasonics,Condensed Matter Physics,Electronic, Optical and Magnetic Materials