Capacitance-voltage characteristics of metal-polymer-silicon device with inkjet-printed Ag electrode

Capacitance-voltage (C-V) behaviors of metal-polymer-silicon capacitors having inkjet-printed silver (Ag) electrodes were characterized. Polymers of polyvinyl alcohol (PVA) and poly-4-vinylphenol (PVP) were spin-coated on heavily doped silicon for dielectric layer, on which Ag ink was directly patterned. The C-V characteristics of inkjet-printed Ag devices were compared with those of evaporated Al devices. Cross-linked PVA device (1000 s UV exposure) with inkjet-printed Ag electrode showed higher capacitance and dielectric constant (366 pF, k = 5.10) than the device with evaporated Al electrode (109 pF, k = 1.57, 1 mm radius). For the PVP dielectric layer, device with inkjet-printed Ag showed lower capacitance and dielectric constant than evaporated Al device. Interface states between the polymer dielectrics and metal electrodes were investigated by scanning electron microscopy. In addition, cross-linking of PVA with UV exposure, confirmed by Fourier transformed infrared spectroscopy, critically influenced the flat band voltage for both inkjet-printed and evaporated electrode's devices. Chemical composition of Ag electrode was analyzed by x-ray photoelectron spectroscopy. In summary, it was found that degree of cross-linking, interface states between polymer and electrode, and chemical composition of electrode could determine electrical performances, respectively.