Control of positive and negative threshold voltage shifts using ultraviolet and ultraviolet-ozone irradiation

Influence of UV/Ozone Treatment on Threshold Voltage Modulation in Sol–Gel IGZO Thin‐Film Transistors

“…[12,50] As the number of oxygen-deficient sites (e.g., oxygen vacancies) decreased through the combination of the activated oxygen ions and free electrons in the channel layer, the electrons in the channel layer were reduced, and the threshold voltage (V th ) was modulated in the positive direction. [48] As the UVO treatment period increased, more electrons and oxygen ions generated by the UVO treatment combined and caused a decrease in the number of V o , so the values of V th were further modulated in the positive direction. [32,51] As a result, normally on IGZO TFTs in depletion mode due to high free-electron concentration in the channel layer were converted to enhancement mode by reducing the V o and the free electrons in the channel layer when the V gs was 0 V, as shown in Figure 1b.…”

“…All activated atomic oxygen species deeply affected the surface of the IGZO layer by combining the free electrons on the IGZO surface. [ 48,49 ] Moreover, the UV light had light energies of 647 and 472 kJ mol −1 , which assisted with the removal of organic compounds (e.g., hydrocarbons) and enhanced the formation of a metaloxygen lattice (MO) bonding network. [ 12,50 ] As the number of oxygen‐deficient sites (e.g., oxygen vacancies) decreased through the combination of the activated oxygen ions and free electrons in the channel layer, the electrons in the channel layer were reduced, and the threshold voltage ( V th ) was modulated in the positive direction.…”

Photo-assisted hysteresis of electronic transport for ZnO nanowire transistors

“…Therefore, the electron transport of ZnO nanowires is highly sensitive to their geometry, size, and measuring environments [18][19][20][21][22]. These properties have brought another important characteristic of the nanowires to the fore, which is the hysteretic behavior in conductance with gate bias [15,23,24].…”