Ultrafast and Broadband Self‐Biased Photodetector Using CdSe/CdS Stacked Nanolayered Heterostructure

ABSTRACT The performance scaling to self‐biased and broadband response of photodetectors has been investigated using CVD grown cadmium selenide (CdSe)/cadmium sulfide (CdS) stacked nanolayered heterostructures. Scanning electron microscopic studies revealed an average nanolayer thickness of 20 nm, with overall stacked layer thickness reaching 375 nm for CdSe and 385 nm for CdS, highlighting the formation of phenomenal layered heterostructures. Raman scattering, X‐ray diffraction patterns, and X‐ray photoelectron studies verified the crystallinity and chemical purity of the samples. The optical absorption and luminescence measurements corroborate the presence of promising electronic transitions originating from CdSe, CdS, and interfacial CdSe x S 1−x SNLs spanning the near‐UV to near‐IR regime. The performance of the double Schottky junctions‐based photodetector designed utilizing SNLH demonstrates a distinct photoresponse (e.g., ultrafast rise time, decay time, responsivity, and detectivity as 800 ps, 5.89 ns, 0.73 A/W, and 1.31 × 10 11 Jones, at −10 V bias, respectively) with broad excitation wavelength and maintaining reproducibility over a period of 2660 cycles. The observed low dark current, high detectivity (1.07 × 10 11 Jones), ultrafast rise time of 1.24 ns, and decay time of 10.85 ns at 0 V bias endorses the realization of a self‐biased photodetector for fast communication and sensor applications.