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Float-Zone (FZ) crystal growth process allows for producing higher purity silicon crystal with much lower concentrations of impurities, in particular low oxygen content. Nevertheless, the FZ process occasionally faces the problem of small contamination from oxidation. This can come in the form of a thin oxide layer that may form on un-melted polysilicon surface. The appearance of the oxide layer indicates degraded machine performance and the need for machine maintenance. Therefore, oxide investigation is important for improving both the FZ process and FZ machines, and the first step is oxide recognition. In this study, we characterized oxide into mainly three varieties, according to their surface texture characteristics, which are: (i) spot (ii) shadow and (iii) ghost curtain. We leveraged FZ images captured from the vision system integrated on the FZ machine to establish an oxide dataset. Targeted for data imbalance problem in our dataset, a method based on transfer learning and asymmetric loss for multi-label oxide classification is presented in this work. The results showed that the pre-trained model and the asymmetric loss used for training outperformed the baseline models and improved the classification performance. Furthermore, this study deeply investigated the effectiveness of the components of asymmetric loss. Finally, Gradient-weighted Class Activation Mapping (Grad-CAM) was employed to explain decision process of the models in order to adopt them in the industry.

The R3B collaboration aims to assemble an experimental setup with high resolution and efficiency to perform kinematically complete measurements of reactions with high-energy RIBs (radioactive ion beams). In the R3B experimental setup, the silicon tracker is positioned closest to the target region and can provide high-resolution position measurements of light-charged particles like protons. The three layers of the silicon tracker are constructed with a total of 30 Si double-sidedstrip detectors (DSSD). In this paper, as an option of 23 MeV proton irradiated n-type Float-Zone(Fz)Si double-sidedstrip detector (DSSD) havebeen considered, and by taking the two-trapproton irradiation damage model, the bulk damage effect and the macroscopic performance of the Sidouble-sidedstrip detector (DSSD) have been discussed. The detector is irradiated with three values of proton fluences (equivalent to 1Mev neutron fluence): 2×10 14 ,5×10 14 and 8×10 14 cm -2 . By using the Shockley-Read-Hall recombination (SRH) formulation, the full depletion voltage and leakage current have been measured as a function of the irradiation dose, finally the device and process parameters and specifications for the Si double-sidedstrip detector (DSSD) used in the R3B silicon tracker experimenthavebeen proposed.

Contactless minority carrier lifetime (lifetime) measurements by means of microwave detected photoconductivity are employed for oxidation process characterization and furnace profiling. Characterization is performed on oxidized float zone substrates with high resistivity and outstanding bulk quality, suggesting that the measured effective lifetime is strongly dominated by interface recombination and therefore reflects the oxide quality. The applied approach requires neither test structures nor time consuming measurements and is therefore of particular interest if high throughput is required. The method is used to investigate the impact of oxidation furnace leakage as well as to analyze the oxidation homogeneity across a horizontal oxidation furnace. For comparison, capacitance-voltage measurements are conducted to characterize the oxide properties. It is found that any type of furnace leakage, which induces fixed oxide charges as well as interface states, has a heavy impact on the measured effective lifetime, especially on the shape of generation rate dependent lifetime curves. Furthermore, a distinct lifetime decrease towards the tube door of the oxidation furnace could be observed. The latter is even detectable in an ideal oxidation process, generating high quality oxides. Besides plain equipment characterization, the presented approach is suitable to optimize the oxidation process itself regarding different parameters like temperature, gas flow, pressure, or process time.

We report on the design, simulation and test of Low Gain Avalanche Diodes (LGADs) which utilize a buried gain layer. The buried layer is formed by patterned implantation of a 50-micron thick float zone substrate wafer-bonded to a low resistivity carrier. This is then followed by epitaxial deposition of a ≈ 3 micron-thick high resistivity amplification region. The topside is then processed with junction edge termination and guard ring structures and incorporates an AC-coupled cathode implant. This design allows for independent adjustment of gain layer depth and density, increasing design flexibility. A higher gain layer dopant density can also be achieved by controlling the process thermal budget, improving radiation hardness. A first set of demonstration devices has been fabricated, including a variety of test structures. We report on TCAD design and simulation, fabrication process flow, and preliminary measurements of prototype devices.

Using the penetration and transientness of Terahertz pulses and the photoconductive delayed detection method, the tomographic imaging of the interior of the object based on the time of flight can be realized. By comparing the transmittance of several crystals and polymers in the Terahertz band, Polymethylpentene (TPX) was selected as the material of Terahertz lens, and High Resistivity Float Zone Silicon (HRFZ-Si) as the material of beam splitter; By comparing the focal depth of normal incidence and oblique incidence optics system, the normal incidence optical system was used to realize time-of-flight imaging; Using the idea of optical-mechanical integration, the corresponding optical camera is designed according to the normal incidence optical system, and the peak-to-valley map and thickness map of the Lithium cobaltate coating of aluminum foil were obtained by time-of-flight imaging, and the defects such as complete shedding of the coating and uneven thickness were observed. The results show that the normal incidence optical system can realize Terahertz time-of-flight imaging and is applicable in the industrial nondestructive testing field.

The continuous development of innovative optical materials with lanthanoid ions as activators has emerged as a modern sector of materials chemistry. The experience with the fabrication of single crystals with the optical float zone has motivated one to investigate the luminescence of Nd3+ and Ho3+ ions in the garnets (Gd3−xREx)In2Ga3O12 (RE = Nd and Ho, x = 0; 0.15–0.30). Upon usage of an Ar/O2 (80:20 ratio) atmosphere and application of an auxiliary pressure (6 bar) to suppress In2O3 evaporation, single‐crystalline domain sizes in the order of ≈6 × 6 × 1 mm3 are obtained. Structural analysis confirms the formation of a cubic garnet phase with space group Ia3¯d $I a \\bar{3} d$ , with the substituents incorporated in accordance with Vegard's law. Backscattered electron imaging and energy‐dispersive X‐ray spectroscopy are conducted, demonstrating a homogeneous elemental distribution within the crystals. Photoluminescence studies are carried out, revealing the characteristic narrow‐line 4f n → 4f n transitions of Nd3+ and Ho3+, with decay times in the submillisecond range, suggesting non‐negligible cross‐relaxation effects are present. Despite this, the large nearest‐neighbor Gd–Gd distance (3.88 Å) in Gd3In2Ga3O12 and the low phonon cutoff energy (≈700 cm−1) are found to limit cross‐relaxation pathways, preserving significant photoluminescence brightness. These results highlight the potential of Gd3In2Ga3O12:RE3+ single crystals as promising candidates for advanced optical applications. Nd3+‐ and Ho3+‐doped Gd3In2Ga3O12 single crystals have been successfully synthesized via the optical float zone method. Their structure and optical characterization demonstrate efficient narrow‐line 4f–4f emission, low cross‐relaxation, and bright photoluminescence, indicating their potential as advanced optical materials for photonic applications.

Two different analytic models, in which convection in the float zone is assumed, are developed to understand the solute redistributions during general seeding and quasi-seeding processes of TiAl alloys, respectively. The results suggest that the solute redistribution plays an important effect in the phase selection and microstructural development during the initial stage of seeding processes. In the initial stage of the quasi-seeding process, the interface concentration increases gradually and the solute diffusion boundary forms with the crystal growth of α phase. Correspondingly, a maximum constitutional undercooling with respect to β phase occurs ahead of the solidifying α interface and then decreases gradually. Simultaneously, the position where the maximum constitutional undercooling occurs also moves forward with regard to the interface. While in the initial stage of the general seeding process, the α phase can grow continuously as stable phase when the initial composition of the melt is higher than Al 48.9%. Under the influence of both the constitutional undercooling and Ti5Si3 particles, coarse dendrites form and then are transformed to cellular morphology. Nevertheless, the lamellar microstructure can still be aligned well during the entire seeding process. Besides, it is also found that the thickness of solute diffusion boundary decreases with the increase of convection intensity and thus, the growing interface become more stably correspondingly, which is beneficial to the lamellar alignment of TiAl alloys.

This experiment deals with the influence of co-doping with oxygen and hydrogen and also annealing parameters, temperature and excitation power on the Er related photoluminescence (PL) of silicon. The ultimate goal is to optimise the PL intensity of the Er 3+ internal transition to make at room-temperature luminescence possible. Silicon is a very inefficient light emitter, because of the low radiative recombination rate due to the indirect band gap. However, by adding optically active impurities such as erbium, Si can be made luminescent. Silicon is an ideal material for the fabrication of optical waveguides that are compatible with optical telecommunication technology at 1.54µm, because of its high transparency and high refractive index at this wavelength. Co-doping with oxygen and hydrogen can enhance the initial Er luminescence. To investigate the influence of oxygen and hydrogen on the diffusion process and the luminescence intensity, samples were doped with erbium, oxygen and hydrogen at different concentrations that were implanted both on Float Zone (FZ) and Czochralski (CZ) silicon wafers. In FZ silicon, the samples implanted with both oxygen and hydrogen showed the highest luminescence yield with a six times higher peak intensity as compared to samples implanted with only erbium and a two times higher peak intensity as compared to samples with erbium and oxygen, in accordance with previous results. However, identified by the line position and contrary to previous results on CZ-Si, the luminescence stems from an erbium-oxygen impurity complex and not from the so-called cubic centre. In CZ samples doped with erbium, oxygen and hydrogen show a 3 times higher intensity as compared to samples doped only with erbium and oxygen. Although the PL lines of the cubic centre are visible, they do not exhibit the strongest luminescence. In samples doped only with erbium and hydrogen and annealed at 900°C, we observe luminescence from only the cubic centre. Although the appearance of the cubic centre in these samples is most likely due to out-diffusion of erbium in the absence of oxygen, hydrogen again enhances the luminescence intensity by a factor 2.

We built and measured radio-frequency (RF) loss tangent, tan δ, evaluation structures using float-zone quality silicon-on-insulator (SOI) wafers with 5 μm thick device layers. Superconducting Nb components were fabricated on both sides of the SOI Si device layer. Our main goals were to develop a robust fabrication for using crystalline Si (c-Si) dielectric layers with superconducting Nb components in a wafer bonding process and to confirm that tan δ with c-Si dielectric layers was reduced at RF frequencies compared to devices fabricated with amorphous dielectrics, such as SiO2 and SixNy, where tan δ ∼ 10-3. Our primary test structure used a Nb coplanar waveguide (CPW) readout structure capacitively coupled to LC resonators, where the capacitors were defined as parallel-plate capacitors on both sides of a c-Si device layer using a wafer bonding process with benzocyclobutene (BCB) wafer bonding adhesive. Our control experiment, to determine the intrinsic tan δ in the SOI device layer without wafer bonding, also used Nb CPW readout coupled to LC resonators; however, the parallel-plate capacitors were fabricated on both sides of the Si device layer using a deep reactive ion etch (DRIE) to access the c-Si underside through the buried oxide and handle Si layers in the SOI wafers. We found that our wafer bonded devices demonstrated F· δ = (8 ± 2) × 10-5, where F is the filling fraction of two-level states (TLS). For the control experiment, F· δ = (2.0 ± 0.6) × 10-5, and we discuss what may be degrading the performance in the wafer bonded devices as compared to the control devices.

The development of large sized Si (Li) detectors (with a sensitive region diameter more than 110 mm), with high energy and positional resolutions, signal linearity over a wide energy range, for alpha, beta and gamma particles is still a rather difficult technological task. This work proposes a technology to improve manufacturing procedure of p-i-n structured Si(Li) detectors. We consider a method of additional “leveling” drift to already prepared Si (Li) detectors to reach a uniformly compensated sensitive region throughout the entire volume, and to smooth out local areas of uncompensated detector regions at a certain temperature and electric field. Experimentally obtained results show that conducting an additional “leveling” drift process ensures uniform distribution of lithium ions in silicon and is one of the main technological operations. The choice of the temperature-time regime of the “leveling” drift depends on the specific resistance of the initial material. Therefore, an additional “leveling” drift was carried out on detectors obtained by p-type monocrystalline silicon with high resistance (obtained by the float-zone method) and with low resistance (obtained by the Czochralski method), and their electrophysical responses were compared. Consequently, it was determined that for low-resistance materials, “leveling” drift is more effective.