Photodetectors of IR radiation on the basis of CdS 1-x Se x films deposited from solution

Abstract

In this work the results on the investigation of the photosensitivity near the IR region, of CdS 1-x Se x (0 less than or equal to x less than or equal to 0.4) films 8 divided by 9 micrometers thick prepared on glass-ceramic substrates by precipitation from aqueous solutions are presented. The temperature dependence of dark and light conductivity, spectrum and optical quenching of primary and impurity photoconductivity are investigated. The obtained results show that when controlling ionic composition and heat-treatment (HT) conditions, one can purposely control the properties of CdS 1-x Se x (0 less than or equal to x less than or equal to 0.4) films, achieve the appropriate degree of compensation of different recombination levels and traps attributed to intrinsic defects or impurities, which result in high level of photoelectrical parameters near the IR region. Just after deposition the photoconductivity spectrum maximum of CdS 1-x Se x (0 less than or equal to x less than or equal to 0.4) films is observed at (lambda) 1 =0.495 divided by 0.545 micrometers versus the film composition. Subsequent to HT, the photoconductivity spectrum considerably widens and appears the impurity maximums at (lambda) 2 =0.58 divided by 0.69 micrometers and (lambda) 3 =0.95 divided by 1.05 micrometers. At (lambda)=0.88 divided by 1.56 micrometers wavelength region, the primary photocurrent optical quenching (POQ) of the films takes place. The POQ spectrum in photosensitive CdS 1-x Se x films consists band with the maximum at (lambda) max -1.28 divided by 1.38 micrometers, versus the film composition and HT conditions. At optimum conditions, the degree of quenching attains to 12%. The quenching of the primary photoconductivity by infrared light, leads to the occupation of the r-centers by holes.