Optoelectronics applications of electrodeposited p- and n-type Al₂Se₃ thin films

In this paper, energy band gaps and electrical conductivity based on aluminum selenide (Al₂Se₃) thin films are synthesized electrochemically using cathodic deposition technique, with graphite and carbon as cathode and anode, respectively. Synthesis is done at 353 K from an aqueous solution of analytical grade selenium dioxide (SeO₂), and aluminum chloride (AlCl₂·7H₂O). Junctions-based Al₂Se₃ thin films from a controlled medium of pH 2.0 are deposited on fluorine-doped tin oxide (FTO) substrate using potential voltages varying from 1,000 mV to 1,400 mV and 3 minutes −15 minutes respectively. The films were characterized for optical properties and electrical conductivity using UV-vis and photoelectrochemical cells (PEC) spectroscopy. The PEC reveals a transition in the conduction of the films from p-type to n-type as the potential voltage varies. The energy band gap reduces from 3.2 eV to 2.9 eV with an increase in voltage and 3.3 eV to 2.7 eV with increase in time. These variations indicate successful fabrication of junction-based Al₂Se₃ thin films with noticeable transition in the conductivity type and energy band gap of the materials. Consequently, the fabricated Al₂Se₃ can find useful applications in optoelectronic devices.