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 (VH) shifted more negatively under PBITS than under PBTS; amount of shift of VH 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 (VO+ or VO+2) provided by illumination contributed to induce hump phenomenon than in darkness.