CdSe0.4Te0.6 Quantum Well Based Photodetector Toward Imaging Vision Sensors

CCD and CMOS sensors used in imaging vision have a sensitivity range for wavelengths from approximately 0.4 to $0.9~\mu \text{m}$ when silicon (Si) technology is used. Imaging in adverse weather conditions such as fog, rain, and snow is related to imaging density variations in media where the sensed image is better detected in infra-red wavelengths or at even longer wavelengths. Near-wave infra-red (NIR) and short-wave infra-red (SWIR) technologies based on arrays of indium gallium arsenide (InGaAs) photodiodes are typically defined as light sensing in the $0.75~\mu \text{m}$ - $0.9~\mu \text{m}$ and $0.9~\mu \text{m}$ – $1.7~\mu \text{m}$ wavelength ranges, respectively and are used as alternatives for this purpose. Although infra-red and higher spectra can be sensed using NIR and SWIR technologies, there is strong market demand for more efficient, cheaper, faster, and smaller camera sensors. Because of their wide bandgap and easy and relatively inexpensive deposition techniques, II–VI compound semiconductors are at the forefront of materials that are being studied for developing imaging sensors. In this paper, a CdSeTe based photodiode is proposed as an alternative for imaging sensor under adverse conditions. A thermal evaporation technique was used to fabricate a Glass/ITO/CdS/CdSe/CdSe0.4Te0.6/CdSe/Ag photodetector. A comprehensive analysis of the structural and electrical properties of the device confirmed a quantum well (QW) heterostructure with an 18 nm CdSe0.4Te0.6 active layer. Practical measurements demonstrated responsivity and specific detectivity for wavelengths between 0.5 and $1.1~\mu \text{m}$ with power conversion efficiency ( PCE ) of 10.4%.