Electrical Characterization Of KCu₇S₄ Quasi 1D Nanostructures And Nanodecives Based On Them

Low-dimensional nanomaterials have many applications in the field of nanodevices due to their unique optical,electrical,magnetic and mechanical properties.K-Cu-S system materials can be obtained by doping K ion into ternary copper-chalcogenide?K-Cu-S?.KCu₇S₄ is an important one.Its lattice consists of a three-dimensional Cu-S framework with pseudo-one-dimensional channels,so the KCu₇S₄ provides both a large aspect ratio and a direct path for charge transport.Herein,KCu₇S₄ quasi 1D nanostructures were synthesized through a solution-based method.Electrical characterization and nanodevices based on them were researched.The specific research results are as follows:1.KCu₇S₄ nanobelts with width 100-300 nm and length up to hundreds of microns were synthesized in a strong alkaline solution,using KOH as K source,CuCl₂·2H₂O as Cu source,and Na₂S·9H₂O as S source.XRD and XPS analysis verified the product to be body-centered tetragonal KCu₇S₄ with pure phase and good crystalline.UV-Vis-NIR absorption spectra showed a significant absorption peak in the NIR region,indicating that KCu₇S₄ has the potential application in the field of NIR photodetectors.2.Ordered monolayer KCu₇S₄ thin films were assembled using the Langmuir-Blodgett technology and a KCu₇S₄/Si heterojunction was constructed.The device demonstrated splendid self-driving characteristics when illuminated by the incident light(980 nm,295.3?W cm^-2),showing a responsivity of 15 mA W^-1 and a detectivity of 2.15×10¹² cm Hz^1/2 W^-1.Significantly,the device works well under high pulsed light irradiation up to 50 kHz with a high-speed response?response time?_r 7.4?s and recovery time?_f 8.6?s?,which can be used as the high performance NIR photodetectors.3.Through the spontaneous oxidation of Cu during evaporation,KCu₇S₄/Cu_xO/Au heterojunctions with different thickness Cu_xO layer were fabricated by using UV lithography and e-beam evaporation technology.Electrical characterization showes that the thickness of the Cu_xO layer has a remarkable effect on the resistance switch behavior of the device.The device with 16 nm Cu_xO layer exhibits a typical bipolar resistance switching behavior after a“forming”process,while the device with 32 nm Cu_xO layer can only show the unipolar resistance switch behavior in the range of positive voltage.The results may also provide guidance for the improvement of the performance and stability of Cu-based nonvolatile memory devices.