Synthesis, Crystal Growth, and Annealing of CdS_xSe_1–x and Cr:CdS_0.8Se_0.2 Single Crystals

Abstract

Mid-infrared laser in the 2–5 μm wavelength region is in the atmospheric transmission window range, and hence, it has important application prospects in the fields of optoelectronic countermeasures, space communication, environmental remote sensing, and molecular spectroscopy. One of the most promising technological approaches to achieve mid-infrared laser output is based on direct lasing of transition-metal (TM)-doped II–VI chalcogenide crystals. In this work, CdS x Se1‑x and Cr:CdS0.8Se0.2 polycrystals were synthesized by a chemical vapor synthesis method from a stoichiometric mixture of vacuum-sublimed CdS and CdSe. The structure of the synthesized products was analyzed by X-ray diffraction (XRD). Using these synthesized products, CdS x Se1–x and Cr:CdS0.8Se0.2 single crystals were grown by the physical vapor transport (PVT) method. After annealing, the band gap becomes smaller and the transmission range widens to 17 μm. The composition of the single crystals was determined by energy-dispersive spectrometry (EDS) mapping and XPS, and it was found to be uniform throughout the ingot. In addition, the absorption peak maximum for the Cr2+ ion in the Cr:CdS0.8Se0.2 crystal is at 1.84 μm.

Aerosol-assisted chemical vapor deposition of MSe and MSSe thin films using zinc(ii) and cadmium(ii) single source precursors containing hybrid Se,X-PNC ligands

“…On the other hand, Cd-containing spectra showed Cd-3d core level peaks assigned to Cd-3d 5/2 and Cd-3d 3/2 (D spin-orbit splitting = 6.8 eV) at 405.51 and 412.31 eV BEs for 5F and 405.31 and 411.11 eV BEs for 6F, suggesting the presence of Cd 2+ interacting with selenium. Both the binding energy and the FWHM (1.04 and 1.06 eV) were in good agreement with those reported for CdS x Se 1Àx 62,72,73 and CdSe films. 63,74 No significant changes were observed in FWHM between 5F and 6F.…”

Spectroelectrochemical Characterization of Energetics in Type I vs Quasi-Type II Heterojunctions in CdSe@CdS Nanorod Films

“…Further discussion of these XPS data are integrated into the presentation below and are summarized here: (a) All NRs that were prepared for spectroelectrochemical characterization demonstrate significant enrichment of Cd in the near-surface region, to an extent greater than seen for low-coverage CdSe and CdS tethered quantum dots that have been exposed to ambient atmosphere during processing. 28,39 Cd 3d peak shapes suggest predominantly one form of near-surface Cd, which we have previously posited is due to fully coordinated Cd atoms and less than 5% relative concentration of Cd in undercoordinated environments, 39,75 activation appears to have been degraded and oxidized, which, as we discuss below, is likely critical to electrochemical equilibration of a fraction of the NR film with the underlying ITO contact. (c) Li + is incorporated into the near-surface region of all NR films after they have been exposed to electrolyte, with Li:Cd ratios approaching 1:1, regardless of whether the NRs have been taken to potentials where electron injection and absorbance bleaching are seen or not.…”

“…The compositions of these NR films were evaluated using XPS, as we have shown before for CdSe QD films with and without capping ligands. , The full XPS spectra and relative atomic ratios are shown in the Supporting Information, Section 4. Further discussion of these XPS data are integrated into the presentation below and are summarized here: (a) All NRs that were prepared for spectroelectrochemical characterization demonstrate significant enrichment of Cd in the near-surface region, to an extent greater than seen for low-coverage CdSe and CdS tethered quantum dots that have been exposed to ambient atmosphere during processing. , Cd 3d peak shapes suggest predominantly one form of near-surface Cd, which we have previously posited is due to fully coordinated Cd atoms and less than 5% relative concentration of Cd in undercoordinated environments, , along with small concentrations (<5%) of a CdO-like near-surface species which disappears upon immersion in electrolyte. (b) The carbon present from the remaining capping ligands after UV-ozone activation appears to have been degraded and oxidized, which, as we discuss below, is likely critical to electrochemical equilibration of a fraction of the NR film with the underlying ITO contact.…”

Growth and Variable Temperature Hall Effect Study of SrPb3Br8 Crystal with Low Phonon Energy

“…In the present work, we successfully grew the SrPb 3 Br 8 single crystal via vertical Bridgman method, [23,24] and used X-ray diffraction and X-ray photo-electron spectroscopy tests to detect the phase composition of the single crystal and the element states of the surface of the processed wafers, respectively. Then, Raman and transmission tests were carried out to investigate the phonon energy and optical properties of the samples.…”