Insulator-to-metal transition of vanadium oxide-based metal-oxide-semiconductor devices at discrete measuring temperatures

In this article, crystallinity and phase dependent insulator-to-metal transition (IMT) of vanadium oxide (VO)-based metal-oxide-semiconductor (MOS) devices is studied at higher measuring temperatures where the sputtered VOs are deposited in different Ar:O₂ ratios at room temparture. The VO phases were identified by differential scanning calorimetry and synchrotron-based grazing incidence x-ray diffraction techniques. A change in the crystalline to amorphous nature of the as-deposited films is observed with increasing O₂ partial pressure (pO ₂) at elevated substrate temperatures. The I-V trends reveal an electrically-triggered insulator-to-metal transition phenomena at higher temperatures. The IMT has been ascribed to both the increase in carrier concentration in the gate dielectric due to electric-field induced carrier injection and structural phase transition (SPT). The effect of Joule heating also plays a role in the IMT. It is further observed that IMT is absent at certain intermediate temperatures. The temperature dependent quantized IMT suggests a trade-off between various crystalline and amorphous phases of VO. (paper)