This paper reports the successful surface treatments of p-and n-ZnTe thin film semiconducting layers prepared by electrodeposition technique. The surface treatment was carried out by using a chlorine precursor which is CdCl2. The initial experiment carried out by applying CdCl2 treatment to ZnTe layers of approximately 1200 nm showed that the CdCl2 treatment did not introduce additional Cdrelated phase to the ZnTe layers as revealed by the X-ray diffraction (XRD) measurements carried out on glass/FTO/p-ZnTe and glass/FTO/n-ZnTe mono-layers. The electrical conductivity type as determined from photo-electro-chemical (PEC) cell measurement also showed that after applying CdCl2 aqueous solution for the treatment of p-and n-ZnTe layers grown on conducting glass substrates, the type remains unchanged.

The preparation of CdS thin films were actualised with electrodeposition technique using cathodic voltage of 1200 milli – Volts (mV). The optical and electrical properties of three different classes of CdS semiconductors namely as – deposited CdS layers (AD-CdS), CdS layers heat-treated in air without any chemical treatment (HT-CdS) and CdS layers treated with CdCl2 and annealed in air (CC-CdS) have been investigated in this work. Results from optical analysis showed that AD-CdS layers have the least absorption edge and highest energy bandgap. Annealing the CdS thin films without and with CdCl2 treatment brings the energy bandgap to same value of ~2.42 eV. The main distinction between the HT- and CC-CdS layers is that the absorption edge of CC-CdS films is sharper than the HT-CdS. Results from electrical analysis revealed that the magnitude of photo-electro-chemical (PEC) cell signals which give a clue about the doping concentration of the semiconductor material is greater in CC-CdS layers than in AD- and HT-CdS layers.Keywords: AD-CdS, HT-CdS, CC-CdS, Energy Bandgap, Absorption Edge, PEC Cell Signal.

The growth of aluminum gallium selenide (Al 2 GaSe 3 ) 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 (AlCl 3 .6H 2 O) as Al 3+ source, 0.1 M gallium chloride (GaCl 3 ) as Ga 3+ source and 0.01 M SeO 2 as Se 2source in 800 mL of deionised water. The bath temperature was maintained at 70 o C and a cathodic potential of 1200 mV was used for the thin films deposition. The electrical and optical properties of the electrodeposited Al 2 GaSe 3 thin films were characterized using photo-electro-chemical (PEC) cell measurement and ultravioletvisible spectrophotometer respectively. It was observed that the optical band gaps of the Al 2 GaSe 3 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 Al 2 GaSe 3 thin films.