n-Type KCu3S2 microbelts: optical, electrical, and optoelectronic properties

Abstract

KCu₃S₂ microbelts with lengths up to 80 μm and widths of 200–800 nm have been synthesized using a composite-hydroxide mediated (CHM) approach and their optical, electrical and optoelectronic properties were systematically characterized for the first time. As-synthesized KCu₃S₂ microbelts were characterized to be semiconductors with a bandgap of 1.64 eV by UV-vis absorption spectroscopy and room-temperature PL spectroscopy. Ultraviolet photoelectron spectroscopy (UPS) and the electrical transport properties of the bottom-gate field-effect transistor (FET) revealed the n-type conduction of the KCu₃S₂ microbelts with a conductivity as high as ∼1.85 × 10³ S cm⁻¹. A KCu₃S₂/Au Schottky diode was fabricated, which showed a turn-on voltage of ∼0.3 V, a rectification ratio of ∼10² to 10³, and an ideality factor of 2.1. The diode possessed a photoresponse ratio I_light/I_dark ∼ 50 and a rapid response time less than 0.5 s. The systematical electrical characterization of KCu₃S₂ microbelts sheds light on the potential application of KCu₃S₂ as a photovoltaic or optoelectronic material.