Solution-processed Ta doped heterojunction structure ITO/ZTO thin film and application for high electrical and stable TFTs

Abstract

Here, the solution-processed heterojunction structure Ta doped ZnSnO/InSnO (TaZTO/ITO) semiconductor thin film and TFTs have been fabricated on atomic layer deposition deposited Al2O3. The effects of Ta doping on the structure, thickness, thermal decomposition, contact angle, surface morphology, transmittance, chemical bond states and electrical characteristics of ZTO back-channel layer have been investigated by glancing angle incidence X-ray diffraction (GIXRD), cross sectional transmission electron microscopy (TEM), thermogravimetric analysis (TGA), contact angle meter, atomic force microscopy spectrometer (AFM), spectrometer, X-ray photoelectron spectroscopy (XPS) and semiconductor characterization system, respectively. Moreover, the influence of Ta doping in the electrical property and stability of heterojunction structure TaZTO/ITO TFTs has been also analyzed. A proper Ta concentration in the TaZTO back-channel layer can realize stable, dense film and good electrical and stable heterojunction structure TFTs due to inhibiting the generation of defects originated from oxygen vacancies. The heterojunction structure TaZTO/ITO TFTs with 1%mol Ta doping shows the best electrical property with the mobility (μ) of 4.72 cm2/Vs and the best stability with the threshold voltage shift of 0.95 V under positive bias stress. The strategy has coordinated the relationship between μ and stability effectively, and provide a new way for the development of oxide TFTs technology in the future.