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

Fabrication and evaluation of spin-coated trans-DBPen [D5488]-based OFETs

< Substrate>

• Bare Si/SiO₂ (thickness of SiO_2: 200 nm)
• OTS-treated Si/SiO₂ (thickness of SiO_2: 200 nm)
• ODTS-treated Si/SiO₂ (thickness of SiO_2: 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, 3 min)
  4. UV/O₃ treatment (1 h)
  5. Immersion in OTS solution (0.01 M toluene, 16 h, N₂)
  6. Ultrasonication (Toluene, Acetone, IPA, 10 min each)
• n-Octyltrichlorosilane (ODTS) [T3815]
  1. Piranha etching (H₂SO₄:H₂O₂=4:1, 80ºC, 2h)
  2. Ultrasonication (Deionized water, Acetone, IPA, 10 min each)
  3. Exposure to vapor (IPA, 3 min)
  4. UV/O₃ treatment (1 h)
  5. Immersion in ODTS solution (0.01 M toluene, 16 h, N₂)
  6. Ultrasonication (Toluene, Acetone, IPA, 10 min each)

< Vacuum Deposition>

• Deposition rate of trans-DBPen [D5488] 0.3 Å/s (under a pressure of∼10⁻⁴ Pa)
• Substrate temperature during deposition: 60 °C
• Deposition rate of Au: 0.7 Å/s

< Post-Annealing Treatment>

• Annealing condition: 120 ºC, 5 min, N₂

< Device Configuration>

• [n⁺-Si/SiO₂ (200 nm) / trans-DBPen [D5488] (60 nm) / Au (40 nm)]
• Top-Contact Bottom-Gate Type (TCBG)
• Channel Length: 50 μm
• Channel width: 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 C_i (V_G − V_th)²