Annealing temperature induced variation on the electrical and photoelectrical characteristics of Al/Feq₃/p-Si/Al heterojunction diode

Iron tris(8-hydroxyquinoline) (Feq₃) is thermally stable up to 310 °C. Feq₃ thin films are used to fabricate Al/Feq₃/p-Si/Al heterojunction diode. Based on the thermal properties, the device is annealed at 210 and 280 °C. In order to understand the diode behavior, as-deposited and annealed films are characterized by X-ray diffraction, transmission electron microscope and spectrophotometric measurements of transmittance. Annealing is found to influence the optical band gap of the films. The current–voltage (I–V) characteristics were measured for as-fabricated and annealed temperatures in dark and under illumination. The dark electrical parameters of diode are investigated, from which the ideality factor (n), potential barrier height (ϕ) and series resistance (R_s) of the as-fabricated and annealed Al/Feq₃/p-Si/Al heterojunction are determined. These diode parameters are estimated and discussed in terms of both conventional I–V characteristics and Cheung–Cheung functions. The diode under illumination is found to be influenced by annealing and is found to have photoconduction characteristics in which the photoresponsivity (at − 1 V) of as-fabricated and annealed diode at 280 °C are estimated as 2.77 × 10^–4 and 2.55 × 10^–3 A/W, respectively.