Optical, electrical, structural and magnetic properties of BiSe thin films produced by CBD on different substrates for optoelectronics applications

Abstract

BiSe thin films have been grown on substrates as PMMA, ITO, glass and Si wafer by using chemical bath deposition (CBD) method. Deposition temperature and time and pH are kept to be constant during the production of the thin films. The thickness of BiSe thin films, which are produced on ITO, glass, PMMA and Si wafer substrate are 513, 468, 1039 and 260 nm, respectively. According to GAXRD results, the films, which are grown on glass and PMMA substrate, have amorphous structure, but, the films, which are grown on ITO and Si wafer substrate, have peaks of Bi2Se3 crystal. Grain sizes, crystallization number per unit area and dislocation density for ITO and Si wafer substrate are calculated as 112.40 nm and 43.04 nm; 2.25 × 10−5 and 7.91 × 10−5 (1/nm2); 40.11 × 10−5 (1/nm2) and 53.96 × 10−5 (1/nm2), respectively. The contact angles and critical surface tension of distilled water, ethylene glycol, formamide and diiodamethane liquids for thin films grown on glass, ITO, PMMA and Si wafers were obtained by the Zisman method. The % transmittance and % reflectance values of thin films grown on glass, ITO, PMMA are calculated as % T: 79.90, 92.76 and 67.37; % R: 6.18, 2.07 and 10.59, respectively. Eg values of thin films grown on glass, ITO, PMMA are calculated as Eg = 1.92; 2.18; 1.60 eV. The extinction coefficients, refractive indexes and relative dielectric constants of thin films grown on glass, ITO, PMMA are calculated as k = 0.007; 0.002 and 0.012; n = 1.65; 1.34 and 1.96; e 1 = 0.271; 0.083 and 0.528 respectively. Sheet resistance, hall mobility, sheet carrier densities, bulk carrier densities and conductivity types for glass, ITO, PMMA and Si are 6.52 × 107, 6.65 × 101, 1.09 × 108 and 6.45 × 102 (Ω/cm2); 2.38, 1.21 × 10−1, 5.34 and 1.52 (cm2/V.s); 4.01 × 1010, 7.71 × 1017, 1.06 × 1010 and 6.34 × 1015 (cm−2); 4.58 × 1014, 1.50 × 1022, 1.02 × 1014 and 2.89 × 1020 (cm−3); p, n, p and p, respectively. In addition, I–V characteristics and changes of magnetoresistance values versus magnetic field of the thin films are obtained by Van der Pauw method and HEMS.