Near-zero IR transmission of VO2 thin films deposited on Si substrate

The Effect of Substrate Biasing during DC Magnetron Sputtering on the Quality of VO2 Thin Films and Their Insulator–Metal Transition Behavior

“…On the other hand, the transition temperature T t of VO 2 thin films deposited with bias increases significantly compared with those deposited without biasing. VO 2 thin films deposited without biasing show T t of 335 K as we reported previously [23], whereas T t of VO 2 thin films deposited with biasing reaches up to 349 K in this work. Usually the variation of the transition temperature has been associated with the stress and microstructure of the samples [28].…”

“…All the samples show a polycrystalline structure with a few small grains on top of large grains due to secondary nucleation. In our previous work [23], the average grain size of the VO 2 thin films deposited for 2 h (150 nm thick) without substrate biasing was 55.4 nm as shown in Figure 2e. However, the grain size of the VO 2 thin films deposited under the same conditions but with substrate biasing for 2 h (68 nm thick) was much higher and reached 88.6 nm, as shown in Table 1.…”

“…Figure 8 provides a summary of transmittance vs temperature curves under heating and cooling schedules for all the samples; the results are generally consistent with those in Figure 4 and Figure 5 and the implications in 6. The comparison of the hysteresis width (Δ H ) of 5 °C in VO 2 thin films deposited without any bias [23], shown in Figure 7e, indicates that the VO 2 thin films deposited with biasing exhibit quite wider hysteresis loops. The Δ H widening can be attributed to grain boundaries and defects induced by the bias, and the enlarged grain size.…”

“…SEM images of VO 2 thin films deposited on Si substrates for 2 h with bias voltage of: ( a ) 89 V; ( b ) 126 V; ( c ) 146 V; ( d ) 173 V; ( e ) no bias on a sample prepared as in [23]. …”

“…In previous works, it has been found that the substrate biasing during deposition can change both the microstructure and properties of VO 2 thin films [23,24,25]. In this work, the effects of substrate biasing are systematically investigated with the goal of increasing the transition temperature of VO 2 .…”