Growth and characterization of PbSe microcrystals via the pulsed laser welding technique

Abstract

Herein lead selenide crystals are fabricated by the pulsed laser welding (PLW) technique within 2 min. The effect of the pulse width on the crystallinity, surface morphology, structural parameters, compositional stoichiometry, electric resistivity and dielectric constant is considered. It is observed that the PLW technique allowed the growth of the crystals in a short period of time. The grown PbSe crystals are mostly cubic containing tetragonal SeO2 as a minor phase. Selenium oxide presented due to the surface oxidation of PbSe after exposing the crystals to air. Remarkable decreases in the electrical resistivity and increase in the dielectric constant by more than two orders of magnitude are achieved as the pulse width increases from 10 to 50 ms. It is observed that the optimum pulse width revealing the highest dielectric constant value is 30 ms. For these samples, a negative capacitance effect is observed for ac signals of frequencies larger than 700 MHz. In addition, analyzing the microwave cut-off frequency spectra for an imposed signal of low amplitude displayed cut-off frequency values larger than 100 GHz at the point where negative capacitance dominates and ac conductance shows a maxima. The features of the PbSe crystals which are prepared in 2 min nominate them for use as negative capacitance sources and band filters suitable for 6G technologies