Details

Autor(en) / Beteiligte

• Takeda, Yujiro
• Takahashi, Takanori
• Miyanaga, Ryoko
• Bermundo, Juan Paolo S.
• Uraoka, Yukiharu

Titel

Degradation Due to Photo-Induced Electron in Top-Gate In-Ga-Zn-O Thin Film Transistors With n− Region Under Negative Bias Stress and Light Irradiation

Ist Teil von

• IEEE electron device letters, 2023-05, Vol.44 (5), p.765-768

Ort / Verlag

New York: IEEE

Erscheinungsjahr

2023

Link zum Volltext

• IEEE_Xplore

Quelle

IEEE Electronic Library (IEL)

Beschreibungen/Notizen

• We investigated the positive threshold voltage (<inline-formula> <tex-math notation="LaTeX">{V}_{\text {th}}{)} </tex-math></inline-formula> shift with hump and on-current (<inline-formula> <tex-math notation="LaTeX">{I}_{\text {on}}{)} </tex-math></inline-formula> reduction in top-gate In-Ga-Zn-O (IGZO) thin film transistors (TFTs) after negative gate bias of −20 V at 60°C and light irradiation stress (NBTIS). This degradation can be classified into three types of mechanism. 1. The hump at low gate voltage (<inline-formula> <tex-math notation="LaTeX">{V}_{\text {g}}{)} </tex-math></inline-formula> is a sub-transistor effect caused by hole trapping at the IGZO/top gate insulator (TGI) interface. 2. The positive shift of <inline-formula> <tex-math notation="LaTeX">{V}_{\text {th}} </tex-math></inline-formula> is caused by the trapped photo-induced electrons at the IGZO/bottom gate insulator (BGI) interface. 3. The <inline-formula> <tex-math notation="LaTeX">{I}_{\text {on}} </tex-math></inline-formula> reduction occurred due to trapped photo-induced electrons at interface between <inline-formula> <tex-math notation="LaTeX">\text{n}^{-} </tex-math></inline-formula> region of IGZO/BGI interface. The electric field induced by trapped electron promotes depletion of the channel region at the IGZO/BGI and IGZO/TGI interface and <inline-formula> <tex-math notation="LaTeX">\text{n}^{-} </tex-math></inline-formula> region of IGZO/BGI interface, which corresponds to a drop in effective gate and drain voltage, respectively. Thus, the positive <inline-formula> <tex-math notation="LaTeX">{V}_{\text {th}} </tex-math></inline-formula> shift and <inline-formula> <tex-math notation="LaTeX">{I}_{\text {on}} </tex-math></inline-formula> reduction occurred due to trapping of photo-induced electron under NBTIS. Based on our proposed mechanism, this degradation was suppressed by the dual-gate structure.