Improvement of the Electrical Performance of Ag/MEH-PPV/SiNWs Schottky Diode by the Insertion of a Thin Layer of MEH-PPV Polymer and Study of the Annealing Effect

Abstract

Poly[2-methoxy-5-(2′-ethylhexyloxy)-1,4-phenylene vinylene] (MEH-PPV) thin layer was deposited on silicon nanowires (SiNWs) by electroless dipping method. SiNWs were obtained using Ag-assisted chemical etching process. Scanning Electron Microscopy (SEM) images reveal a vertical alignment of the SiNWs as well as the formation of MEH-PPV layer on their surfaces. The presence of MEH-PPV polymer on the SiNWs surface was confirmed by Energy-dispersive X-ray (EDX). Current–Voltage (I–V) measurements were performed for the electrical characterization of Ag/MEH-PPV/SiNWs diodes before and after annealing. The ideality factor (n), the barrier height (φb) and the series resistance (RS) are determined using the Cheung method. The diode parameters are strongly affected by the immersion duration in MEH-PPV solution as well as the annealing temperature. The rectification rate of the diodes was increased by MEH-PPV deposition. The annealing temperature has a great influence on the diode parameters by the thermal activation of carriers at Ag/MEH-PPV and MEH-PPV/SiNWs interfaces. I–V characteristics show an ohmic character for temperatures above 250 °C. The electrical parameters such as equivalent carrier concentration (ND) and built-in voltage (Vb) and other values of φb are calculated from Capacitance–Voltage (C–V) measurements.