Study On Fabrication And Electric And Optical Properties Of VO_x Thin Films

Vanadium Oxide thin films have excellent thermal-induced and photo-induced phase transition, and its metal-semiconductor phase transition could occur under thermal excitation or optical excitation. In this paper, the same vanadium oxide thin films with Si substrate were fabricated by facing Target Magnetron Sputter, and then some different Rapid Thermal Annealing(RTA) process conditions were employed to treat the samples. In order to study the influence of different RTA conditions on the surface geography, crystallization, electrical and optical functions of the films, Atomic Force Microscope(AFM), X-Ray diffraction(XRD), Four Probe Meter and THz time domain spectroscopy(THz-TDS) were used to detect all kinds of variations.The results indicated that particles of the samples grow up but crystal grains almost have no change as the RTA temperature increases(RTA time fixed); both particles and crystal grains grow up as the RTA time delays(RTA temperature fixed). In the temperature cycles 20-80℃, Sample(450℃/15s) has no electrical and optical phase transition, the resistivity and THz transmission of Sample(500℃/15s) , sample(550℃/15s), Sample(500℃/10s) and Sample(500℃/20s)have huge change around the phase transition point. But the phase transition point of sample(550℃/15s) is lower than other samples; the transition amplitude of Sample(500℃/10s) is larger than others. Moreover, the transitions of electrics and optics are not synchronous, namely not at the same temperature.At the excitation of 532nm laser, the sample untreated and the Sample(450℃/15s) have good modulation to THz wave. But the samples don't exhibit good modulation to THz wave as well, which have large transitions excited by heat.