Derivation of density of states in amorphous AlZnSnO thin film transistors by changing oxygen contents

The fabrication and the characterization of bottom-gate thin-film transistors (TFTs) utilizing aluminum-zinc-tin-oxygen (AZTO) as a channel material has been studied. The AZTO channel was deposited by radio frequency (RF) magnetron sputtering at room temperature, with varying oxygen and argon ratios. Comprehensive measurements, including transfer curve, temperature stress (TS), negative bias temperature stress (NBTS), activation energy, and density of states (DOS), were conducted to assess the electrical properties of the TFTs. The results indicated that higher oxygen concentrations during deposition led to enhanced stability of the TFTs, primarily by reducing oxygen vacancies. The study highlights the potential of oxide semiconductors, specifically AZTO, in display applications, offering high performance and efficiency. Comparative analysis revealed that AZTO exhibits properties similar to indium-gallium-zinc oxide, making it a viable alternative. The investigation into the effects of varying argon-to-oxygen ratios provides valuable insights into the fundamental processes governing the electrical behavior of AZTO-based TFTs. The calculated activation energy and DOS further elucidate the underlying mechanisms, reinforcing the material’s suitability for advanced electronics and display technologies.