Fabrication and Evaluation of Organic Field-Effect Transistors (OFETs) : Pentacene

Fabrication and evaluation of vacuum-deposited Pentacene [P2524]-based OFETs

< Substrate >

• Bare Si/SiO₂ (thickness of SiO₂ : 200 nm)
• OTS-treated Si/SiO₂ (thickness of SiO₂：200 nm)

< Self-Assembly Monolayer (SAM) Treatment >

• n-Octyltrichlorosilane (OTS) [O0168 ]
  1. Piranha etching (H₂SO₄:H₂O₂=4:1, 80ºC, 2h)
  2. Ultrasonication (Deionized water, Acetone, IPA, 10 min each)
  3. Exposure to vapor (IPA, 3min)
  4. UV/O₃ treatment (1h)
  5. Immersion in OTS solution (0.01 M toluene, 16h, N₂)
  6. Ultrasonication (Toluene, Acetone, IPA, 10 min each)

< Vacuum Deposition >

• Deposition rate of Pentacene [P2524 ]: 0.1 Å/s (under a pressure of∼10⁻⁵ Pa)
• Substrate temperature during deposition: RT
• Deposition rate of Au: 0.3 Å/s, (under a pressure of ∼10⁻⁴ Pa)

< Device Configuration >

• [n⁺-Si/SiO₂ (200 nm) / Pentacene [P2524 ] (60 nm) / Au (60 nm)]
• Top-Contact Bottom-Gate Type (TCBG)
• Channel Length: 50 μm
• Channel width: 1.5 mm: 1.5 mm

< Evaluation Condition >

• Under N₂
• Field-effect mobilities (μ) were determined from the transfer curves in the saturation regime using the following equation: I_D = (W/2L) μ Ci (V_G − V_th)²