Effect of illumination on the hump phenomenon in I -V characteristics of amorphous InGaZnO TFTs under positive gate-bias stress

We measured the current–voltage ( I – V ) characteristics of amorphous Indium‐Gallium‐Zinc‐Oxide (a‐IGZO) thin film transistors (TFTs) to investigate the mechanism that causes the hump in their I – V characteristics under positive bias illumination temperature stress (PBITS) and under positive bias temperature stress (PBTS). Hump phenomenon in subthreshold region in I – V characteristics occurred under PBITS and PBTS. The hump threshold voltage ( V H ) shifted more negatively under PBITS than under PBTS; amount of shift of V H was 6.06 V under PBITS and 3.28 V under PBTS during same stress time, from 2000 to 10,000 s. It is because additional ionized oxygen vacancies ( or ) provided by illumination contributed to induce hump phenomenon than in darkness.