Optimizing the optoelectronic properties of broadband FeS2/Si photodetectors via deposition temperature tuning in chemical bath deposition

This study investigates the fabrication and characterization of n-FeS2/p-Si heterojunction photodetectors using chemical bath deposition (CBD) at deposition temperatures ranging from 50 °C to 80 °C. The impact of temperature on the structural, morphological, and optical properties of FeS2 thin films was evaluated. X-ray diffraction (XRD) revealed polycrystalline cubic FeS2 with improved crystallinity as the deposition temperature increased. The optical energy gaps of the films ranged from 2.41 eV to 1.6 eV, decreasing with higher temperatures. Scanning electron microscopy (FE-SEM) showed that grain size increased from 30 nm to 180 nm as the temperature rose. Hall effect measurements confirmed the n-type conductivity of the film, with mobility decreasing from 5 to 3.17 cm2 V-1 s-1 at higher temperatures. The heterojunctions exhibited rectifying behavior, with the best ideality factor of 1.7 observed at 60 °C. The photodetector fabricated at 60 °C showed superior performance, with a responsivity of 0.37 A W-1 at 520 nm and 0.7 A W-1 at 770 nm, an external quantum efficiency of 52%, and a detectivity of 8 × 1011 Jones at 520 nm, making it the optimal configuration for efficient broadband photodetection.

Inorganic Solar Cells Based on Electrospun ZnO Nanofibrous Networks and Electrodeposited Cu2O

The nanostructured ZnO/copper oxide (Cu2O) photovoltaic devices based on electrospun ZnO nanofibrous network and electrodeposited Cu2O layer have been fabricated. The effects of the pH value of electrodeposition solution and the Cu2O layer thickness on the photovoltaic performances have been investigated. It is revealed that the pH value influences the morphology and structure of the Cu2O layer and thus the device performances. The Cu2O layer with an appropriate thickness benefits to charge transfer and light absorption. The device prepared at the optimal conditions shows the lowest recombination rate and exhibits a power conversion efficiency of ~0.77 %.

Synthesis and modeling of uniform complex metal oxides by close-proximity atmospheric pressure chemical vapor deposition

A close-proximity atmospheric pressure chemical vapor deposition (AP-CVD) reactor is developed for synthesizing high quality multicomponent metal oxides for electronics. This combines the advantages of a mechanically controllable substrate-manifold spacing and vertical gas flows. As a result, our AP-CVD reactor can rapidly grow uniform crystalline films on a variety of substrate types at low temperatures without requiring plasma enhancements or low pressures. To demonstrate this, we take the zinc magnesium oxide (Zn(1-x)Mg(x)O) system as an example. By introducing the precursor gases vertically and uniformly to the substrate across the gas manifold, we show that films can be produced with only 3% variation in thickness over a 375 mm(2) deposition area. These thicknesses are significantly more uniform than for films from previous AP-CVD reactors. Our films are also compact, pinhole-free, and have a thickness that is linearly controllable by the number of oscillations of the substrate beneath the gas manifold. Using photoluminescence and X-ray diffraction measurements, we show that for Mg contents below 46 at. %, single phase Zn(1-x)Mg(x)O was produced. To further optimize the growth conditions, we developed a model relating the composition of a ternary oxide with the bubbling rates through the metal precursors. We fitted this model to the X-ray photoelectron spectroscopy measured compositions with an error of Δx = 0.0005. This model showed that the incorporation of Mg into ZnO can be maximized by using the maximum bubbling rate through the Mg precursor for each bubbling rate ratio. When applied to poly(3-hexylthiophene-2,5-diyl) hybrid solar cells, our films yielded an open-circuit voltage increase of over 100% by controlling the Mg content. Such films were deposited in short times (under 2 min over 4 cm(2)).