Papers by Keyword: Czochralski

Abstract: 1 mol% of neodymium-doped lithium niobium borate (NdLNB) glass and crystal have been produced by using melt-quenching and Czochralski technique, respectively. The synthesis, growth and characterizations of the samples were reported. X-ray diffraction (XRD), Differential thermal analyzer (DTA), Ultraviolet-Visible-Near-Infrared (UV-Vis-NIR) and Photoluminescence (PL) spectroscopic characterizations were made to examine the influence of Nd³⁺ on the physical, structural and optical properties of the samples. Various physical properties such as density, molar volume, ion concentration, polaron radius, inter-nuclear distance and field strength were calculated. The as-quenched glass was amorphous whereas crystal was crystalline as established via XRD studies. UV-Vis-NIR spectra exhibited eight prominent bands centered at 353, 475, 524, 583, 681, 745, 803, 875 nm corresponding to the transitions from the ground state to ⁴D_3/2, ²G_9/2, ⁴G_7/2, ⁴G_5/2, ⁴F_9/2, ⁴F_7/2, ⁴F_5/2, ⁴F_3/2 excited states, respectively. Moreover, the emission spectra at 355 nm excitation displayed several peaks that contributed to the transition of (⁴F_3/2→⁴I_9/2) and (⁴F_3/2→⁴I_11/2), respectively. Fluorescence lifetime was recorded at 53.69 µs for the glass whereas the crystal was recorded at 43.62 µs. It was found that Nd³⁺ ions affected the physical, structural and optical properties of the glass and crystal samples.

Abstract: A successful growth of the titanium-doped lithium niobate (Ti: LiNbO₃) single crystal by Czochralski method is reported. By preserving an effective control of growth parameters such as maintaining accurate temperature gradient by controlling its output power and growth rate as well as wisely choosing the right pulling rate and speed rotation, the Ti:LiNbO₃ single crystal successfully produced using Automatic Diameter Control-Crystal Growth System (ADC-CGS). The structural and optical analyses have been done by using X-ray Diffractometer (XRD), Differential Thermal Analyzer (DTA) and Ultraviolet-Visible (UV-Vis) spectroscopy. The crystallinity of the sample has been confirmed using XRD and DTA has been used to determine the crystal nature of the sample. The position of fundamental absorption edge was recorded via transmission spectra in UV and visible region.

Abstract: Czochralski lifting device is the key equipment for crystal growth. Due to laser crystal growth mechanism could decide its slow growth speed, so Lifting device is required to operate under the ultra-low speed situation chronically. According to shock, shake, fraction and crawl of movement system affected speed stability, the paper carries out a nobel design to laser Czochralski lifting system through alternated servo technology and its precision is analyzed comprenshensively. The long-term experimental data showed by using changed plus PID control method that the system has high precision and better reliability and it is suitable to grow large-size laser crystal. Meanwhile, the design system makes use of common spare parts and can meet the requirements for large scale industrialization.

Abstract: Oxygen-rich crystalline silicon materials doped with boron are plagued by the presence of a well-known carrier-induced defect, usually triggered by illumination. Despite its importance in photovoltaic materials, the chemical make-up of the defect remains unclear. In this paper we examine whether the presence of excess silicon self-interstitials, introduced by ion-implantation, affects the formation of the defects under illumination. The results reveal that there is no discernible change in the carrier-induced defect concentration, although there is evidence for other defects caused by interactions between interstitials and oxygen. The insensitivity of the carrier-induced defect formation to the presence of silicon interstitials suggests that neither interstitials themselves, nor species heavily affected by their presence (such as interstitial boron), are likely to be involved in the defect structure, consistent with recent theoretical modelling.