Influence of oxygen and post deposition annealing on the electrical properties of MnPc and MnPcCl Schottky barrier devices

Abstract

Sandwich structures of manganese phthalocyanine (MnPc) and manganese phthalocyanine chloride (MnPcCl) thin films using aluminium (Al) and gold (Au) electrodes have been prepared by thermal evaporation. Device characteristics of Al/MnPc/Au and Al/MnPcCl/Au are performed and found to show rectification properties. The electrical conductivity has been measured both after exposure to oxygen for 20 days and after annealing at temperature up to 473 K. Current density-voltage characteristics under forward bias (aluminium electrode negative) are found to be due to ohmic conduction at lower voltage regions. At higher voltage regions there is space charge limited conductivity (SCLC) controlled by a discrete trapping level above the valance edge. The electrical parameters of oxygen doped and annealed samples in the ohmic and SCLC region are determined. The reverse bias curves are interpreted in terms of a transition from electrode-limited Schottky emission to the bulk-limited the Poole-Frenkel effect. The Schottky barrier parameters of oxygen doped and annealed structures of MnPc and MnPcCl are determined from the C2-V characteristics.