Self-driven, stable broadband photodetector based on GaAs:CdS heterojunction with ultrahigh on/off ratio and detectivity

Abstract

In this study, a CdS film was successfully coated on GaAs wafer by the facile and easy method of close-spaced sublimation and a high performance visible-UV-IR, self-driven GaAs:CdS photodetector was obtained. Morphological and elemental analysis of the CdS film was performed by SEM, XRD and EDAX, respectively. The fabricated device exhibited an excellent rectification ratio of 4.90×107 in the dark, at ± 2 Vs. Furthermore, GaAs:CdS photodetector showed a superior photoresponse at zero bias, both in visible and in the UV and IR regions, due to the built-in electrical potential. The maximum photodetector parameters of the fabricated heterojunction in visible light were R = 16.91 mA/W (150 mW, V= -2.0 V), D*=8.99×1012 (150 mW, V = 0.0 V) Jones and on/off ratio = 4.27×105 (V = 0.0 V). Furthermore, R = 0.107 A/W (365 nm), R = 0.083 A/W (395 nm), R = 0.104 A/W (850 nm) were obtained at V= -2.0 Volts, while D* values ​​ of 1.972×1013 Jones (365 nm), 1.566×1013 Jones (395 nm), and 1.972×1013 Jones (850 nm) were determined for V = 0.0 Volts. Furthermore, the on/off ratios determined for 365 nm, 395 nm and 850 nm, were 1.79×105, 1.43×105 and 1.54×105, respectively at V = 0.0 V. In addition, after about 40 days, almost no significant degradation of the GaAs:CdS photodetector performance was observed.