Organic-inorganic proximity effect in the magneto-conductance of vertical organic field effect transistors

Vertical organic field effect transistors having a patterned source electrode and an a-SiO₂ insulation layer show high performance as a switching element with high transfer characteristics. By measuring the low field magneto-conductance under ambient conditions at room temperature, we show here that the proximity of the inorganic a-SiO₂ insulation to the organic conducting channel affects considerably the magnetic response. We propose that in n-type devices, electrons in the organic conducting channel and spin bearing charged defects in the inorganic a-SiO₂ insulation layer (e.g., O₂ = Si^+·) form oppositely charged spin pairs whose singlet-triplet spin configurations are mixed through the relatively strong hyperfine field of ²⁹Si. By increasing the contact area between the insulation layer and the conducting channel, the ∼2% magneto-conductance response may be considerably enhanced.