Effect of pH variation on the optoelectronic properties of electrodeposited Al2GaSe3 ternary compound semiconductor

The growth of aluminum gallium selenide (Al2GaSe3) ternary compound semiconductors has been achieved in this work using electrodeposition technique at different electrolytic bath pH values of 2.00, 3.00 and 4.00. The deposition was carried out using a microcontroller – based potentiostat with two-electrode electrochemical cell with the goal of attaining a semiconductor with improved electrical and optical properties. The aqueous electrolytic baths were prepared using 0.1 M aluminum chloride hexahydrate (AlCl₃.6H₂O) as Al³⁺ source, 0.1 M gallium chloride (GaCl₃) as Ga³⁺ source and 0.01 M SeO₂ as Se^2- source in 800 mL of deionised water. The bath temperature was maintained at 70⁰C and a cathodic potential of 1200 mV was used for the thin films deposition. The electrical and optical properties of the electrodeposited Al2GaSe3 thin films were characterized using photo-electro-chemical (PEC) cell measurement and ultraviolet-visible spectrophotometer respectively. It was observed that the optical band gaps of the Al2GaSe3 thin films films were pH dependent. The electrical conductivity types obtained were mainly p – type in electrical conduction with the highest PEC signal obtainable at pH of 3.00. Both optical and electrical results revealed pH of 3.00 as an optimum pH to electroplate Al₂GaSe₃ thin films.