<p><em>In this research thin films of Barium Strontium Titanate (BST) has been synthesis with different compositions Ba<sub>0,5</sub>Sr<sub>0,5</sub>TiO<sub>3</sub> and Ba<sub>0,25</sub>Sr<sub>0,75</sub>TiO<sub>3</sub> which doped by Nb<sub>2</sub>O<sub>5</sub> (Niobium) and Ta<sub>2</sub>O<sub>5</sub> (Tantalum) on Si (100) type-p substrate. Thin films were produced by chemical solution deposition technique (CSD) and spin coating technique with annealing temperature at 850<sup>o</sup>C, 900<sup>o</sup>C dan 950<sup>o</sup>C. Rotation velocity at 3000 rpm and time of rotation is 30 seconds. Characterization of Films is optic Characterization (absorbance ana reflectance). From the Characterizations were obtained BNST thin film with 5% doping and anneling temperature at 850<sup>0</sup>C as photodiode light sensor which applied in electronic circuit. </em></p>