Channel length specific broadspectral photosensitivity of robust chemically grown CdS photodetector

Abstract

CdS grown by chemical bath deposition (CBD) technique is very simple, robust, economical method and has potential large scale applications in solar cells, photovoltaic, photodetectors, sensors and optoelectronic devices. Here we report channel lengths (CLs) specific broadspectral photoresponse properties of commonly grown robust CdS films by CBD. The broadspectral dependent current flow has been observed in all CLs and the rise and decay times have been measured in milliseconds for visible wavelengths (400-700nm). The rise time curves showed linear dependency when measured for CLs 300, 500 and 700nm and non-linearity was observed for CLs 7μm, 45μm and 350μm. We have noticed that decrease in channel lengths down to nanometers (300 nm) increases the response time. Three steps decay time has been noticed for all CLs. The shorter channels (nm) showed two trends in decay time, small increase for wavelengths 550nm. Finally, CLs specific broadspectral photosensitivity has been investigated which indicates the device geometry and fabrication method play an important role for defining the CdS based photodetectors or simulating the characteristics of a photodetector.