Enhancement in the Microelectronic Properties of a PFB–CdSe Quantum Dots Nanocomposite Based Schottky Barrier Diode

Abstract

This paper reports on the electronic and interfacial properties of a Schottky barrier diode (SBD) prepared from a blend consisting of a matrix semiconductor, poly(9,9-fluorufluorene) (PFB), and a dopant, cadmium selenide (CdSe) quantum dots (QDs) having size less than 5 nm. A uniform blend of PFB and CdSe QDs is prepared in chloroform 1:1 by volume and from a 0.5 wt.% of CdSe QDs and 20 mg/mL of PFB. The Schottky device ITO/PEDOT:PSS/PFB–CdSe/LiF/Ag is fabricated by spin coating the PFB–CdSe QDs blend on a pre-deposited PEDOT:PSS/ITO layer. Lithium fluoride (LiF) and silver (Ag) are thermally deposited via vacuum thermal evaporator as buffer layer and ohmic contact, respectively. The fabricated SBD is studied by current–voltage (I–V) characteristics under dark conditions at 300 K. The device exhibits rectifying behavior with rectification ratio of 301.28 at ± 2.5 V. The interface properties of the device such as series resistance (Rs), barrier height (ϕB), ideality factor (n) and reverse saturation current (I0) are measured to be 58.6 kΩ, 0.99 eV, 1.7 and 2.01 × 10−11 A, respectively. Charge carrier conduction mechanisms across the device such as Richardson–Schottky and Poole–Frenkel effects are studied where Schottky emission was identified at lower voltages while at higher voltages Poole–Frenkel effects were observed.