Nitrocellulose-based collodion gate insulator for amorphous indium zinc gallium oxide thin-film transistors

A novel organic material named ‘collodion’ was suggested as a gate insulator for amorphous indium gallium zinc oxide thin-film transistors (a-IGZO TFTs). To find the optimized condition of the collodion gate insulator (CGI), the following three parameters of collodion solution were controlled: (1) the concentration of collodion solution; (2) the number of stacked layers; and (3) the spin-coating speed. The single-layered diluted CGI (collodion:ethanol=1:1) that was fabricated with a 3 krpm spin-coating speed exhibited an acceptable dielectric strength (J < 10−10 A/cm2 in the range of 1.1 MV/cm) and a high-dielectric constant (∼6.57) for the gate insulator layer. As a result, a-IGZO TFTs with CGI showed high-field effect mobility (∼17.11 cm2/Vs).