Deep UV light sensitive Zn1−x−yMgxAlyO films with fast photoelectric response for SAW photodetectors

Optical, structural and photo-electric properties of Zn1−x−yMgxAlyO films on piezoelectric LiNbO3 substrates prepared by PLD method at varied temperatures are studied. The ZnO band gap is enlarged to ∼5 eV by Mg atoms dosing. The reduced growth temperature of 400 °C results in lower conductivity of the film. The films grown at 400 °C-500 °C show deep UV photoelectrical response of 0.1-0.2 ms which is 50-100 times faster compared to devices based on films produced at 600 °C with higher crystallinity. By moderate Al doping and varying the temperature of Zn(Mg, Al)O film growth one may tune the initial sheet conductivity, i.e. the 'working point' of UV SAW detector, to the abrupt slopes of Γ( ) characteristics, thus, optimizing the sensor sensitivity and response time. The UV 'light on/off' sheet conductivity change Δ / dark, defining the sensitivity of UV SAW photodetector is tuned between ∼22% and ∼0.4%.