Electrical and optical characteristics of CdSe Quantum Dot based Schottky diode

Abstract

This article reports the synthesis, fabrication, and characterization of low-cost solution processed CdSe Quantum Dot (QD) based Schottky diode. The CdSe QDs are deposited on the ZnO QDs film over n-Si <100> substrate using solution processing technique. The ZnO QD deposited over the n-Si substrate acting as an Electron Transport Layer (ETL). Further, the Schottky junction is fabricated between CdSe QDs and Palladium (Pd) deposited using electron beam evaporation. The size of CdSe QDs is achieved to be ∼4.84nm less than the Bohr's radius (∼5.6nm) of CdSe. The responsivity and EQE of 0.075 A/W and 18.6% respectively are achieved at a wavelength of 500nm at 5V applied bias. The built-in potential, carrier density, and width of the depletion region at zero applied bias are calculated to be 0.52 V, ∼1.70×1017 cm−3, and ∼33.3 nm respectively. The barrier height is found to be 0.78eV with a reverse saturation current of 1.54×10−8A. Further, the time response characteristics of the device show very fast response with the visible light for a rise time and fall time of ∼20ms.