Effect of Various Crucibles for High Quality AIN Crystal Growth on SiC Seed by PVT Method

Silicon carbide (SiC) has important application prospects in power and radio frequency devices. Obtaining SiC crystals with large diameters and high quality is still a challenge. In this work, the temperature field during SiC crystal growth is investigated through the physical vapor transport (PVT) method. Based on the numerical simulated results, an improved growing system is designed and perfect SiC crystals without any edge defects are successfully obtained. Furthermore, the X‐ray rocking curve, electrical resistivity, and dislocation density of the obtaining SiC crystals are evaluated.

The surface morphologies and structural information of several slice crystals grown by the physical vapor transport (PVT) method were investigated using atomic force microscopy (AFM) and X-ray diffraction (XRD) analysis. Step-like structures were observed by AFM, corresponding with XRD results and the characteristics of layer-plus-island growth mode has been determined on the surface of a crystal grown from PVT, which is different from that of crystal thin film growth by molecular beam epitaxy (MBE) and physical vapor deposition (PVD) in that the driving force depends mainly on the velocity of evaporating source materials, the temperature of the substrate and interactions between molecules. However, the main driving force for the formation of a slice crystal hanging inside the growth tubes from PVT without the influence of substrate depends solely on the interactions between the molecules in the crystal.

Growth of SiC by PVT method with different sources for doping by a cerium impurity, CeO2 or CeSi2

Purification of Cd0.9Zn0.1Te by physical vapor transport method

A recent study reported the rapid growth of SiC single crystals of ~1.5 mm/h using high-purity SiC sources obtained by recycling CVD-SiC blocks used as materials in semiconductor processes. This method has gained attention as a way to improve the productivity of the physical vapor transport (PVT) method, widely used for manufacturing single crystal substrates for power semiconductors. When recycling CVD-SiC blocks by crushing them for use as sources for growing SiC single crystals, the properties and the particle size distribution of the material differ from those of conventional commercial SiC powders, making it necessary to study their effects. Therefore, in this study, SiC single crystals were grown using the PVT method with crushed CVD-SiC blocks of various sizes as the source material, and the growth behavior was analyzed. Simulation results of the temperature distribution in the PVT system confirmed that using large, crushed blocks as the SiC source material generates a greater temperature gradient within the source compared to conventional commercial SiC powder, making it advantageous for rapid growth processes. Additionally, when the large, crushed blocks were vertically aligned, good crystal quality was experimentally achieved at high growth rates, even under non-optimized growth conditions.

Control of powder recrystallization and crystallization interface shape for 8-inch SiC crystal growth by PVT method

Enhanced synthesis of Sn nanowires with aid of Se atom via physical vapor transport

Chromium-doped CdSe is one of the host materials being considered for solid-state tunable mid-infrared (IR) lasers. Alloying CdSe with CdS allows the increase of the thermal conductivity of the crystal (for CdS the thermal conductivity is a factor of 4 larger than CdSe), which is a favorable parameter as a laser host. In this study, we have grown CdSxSe1-x (x ≅ 0.8) single crystals by the physical vapor transport (PVT) method. Crystals with dimensions of 1.2 cm in diameter and 5 cm in length, free of precipitates and inclusions, have been grown. Chromium ions were diffused into the crystal by a postgrowth-diffusion technique at 900°C. Incorporation of Cr ion gives rise to a broad absorption peak at 1.87 µm.

Epitaxial SiC films were deposited on on-axis Si-face 4H-SiC(0001) substrates by the physical vapor transport (PVT) method from a SiC powder. Scanning electron microscopy (SEM) showed a surface morphology which did not have any observable growth defects or cracking. We observed hexagonal growth morphology, a typical characteristic of diffusional growth. River patterns, free from microbubbles and microvoids, were observed on the as-grown surface. Morphology observed at 45° tilt in SEM revealed growth steps and coarsening of grains. An X-ray diffraction (XRD) rocking curve measured the full-width at half-maximum (FWHM) as 51.0 arc seconds and a reciprocal space map showed a singular intense region that is attributed to the high-quality homoepitaxial SiC film.

In this study, the effect of different temperature field distributions on the growth of AlN crystal via spontaneous nucleation by physical vapor transport (PVT) method was investigated through simu...

Tin diselenide single crystals have been grown by the physical vapour transport (PVT) method. Optical absorption studies give an indirect allowed transition at 1.03 eV at room temperature. The electrical resistivity parallel and perpendicular to c‐axis, mobility and carrier concentration have been determined. Dependence of resistivity parallel to c‐axis on temperature gives an activation energy of 0.072 eV. Growth spirals observed for the first time on the as grown faces of these crystals are also presented here.

Based on the physical vapor transport (PVT) method, the growth of large-size CdS crystals inside a vertical semi-closed tube is studied. Firstly, in order to ensure 1D diffusion-advection transport, multi-thin tubes are used in the growth tube. The XRD spectra of the CdS crystal grown in this configuration indicates that the crystal quality has clearly been improved, where the FWHM is 58.5 arcsec. Secondly, theoretical and experimental growth rates under different total pressures are compared; the results show that the experiential growth rate equation is valid for our semi-tube growth, and it could be used to estimate the growth rate and maximum growth time under different total pressures.

Hexagonal aluminium nitride (AIN) microrods with high crystalline quality were grown by physical vapor transport (PVT) method at low growth temperature between 1700 and 1850 degrees C. The length of as-grown microrod is around 1 cm, and the width between 200-400 mu m. The microrod exhibits typical hexagonal geometrical shape with pale yellow color under optical microscopy. Scanning electron microscope (SEM) and atomic force microscope (AFM) images show each microrod with closely arranged step waviness, of which the step interval is 2-4 mu m and the height several nanometers. Raman spectrum characterization showed characteristic peaks of high crystalline AlN. The rod-like structure is attributed to slow growth velocity at lower crystalline temperature, enabling Al and N atoms having enough time to move to the lower energy site and to form heiagonal microrod along direction. High quality hexagonal AlN microrod is an enrichment to one-dimensional semiconductor materials. Data from this study suggest that, by further study on size and impurity control, high performance miniaturized opto-electronic device is hopeful to be achieved.

Silicon carbide (SiC) polycrystalline powder. As the raw material for SiC single-crystal growth through the physical vapor transport (PVT) method, its surface size and shape have a great influence on growth of crystal. The surface size and shape of the evaporation area filled with polycrystalline powder were investigated by numerical simulation in this study. Firstly, the temperature distribution and deposition rate distribution for the PVT system were calculated by global numerical simulation, and the optimal ratio of polycrystalline powder surface diameter to seed crystal diameter was determined to be 1.6. Secondly, the surface of the evaporation area filled with polycrystalline powder was covered by a graphite ring and a graphite disc, respectively, to change its surface shape. The results show that adjusting the surface size and shape of the evaporation area filled with polycrystalline powder is an effective method to control the growth rate, growth stability, and growth surface shape of the single crystal. Finally, the result obtained by selecting appropriate covered structures for actual growth indicates that this process can act as a reference for improving the quality of single crystals.

Basal plane slip is most frequently observed deformation mechanism in 4H type silicon carbon (4H-SiC) single crystals grown by physical vapor transport (PVT) method. It has recently been reported, however, dislocations in such crystals can also glide in the prismatic slip systems. In our study, we have observed non-uniform distributions of three sets of prismatic dislocations in a commercial 4H-SiC substrate wafer. The non-uniformity is likely a result of the distribution of resolved shear stress on each prismatic slip system caused by the radial thermal gradients in the growing crystal boule. A radial thermal model during PVT growth has been developed to estimate the thermal stress across the entire area of the crystal boule. The model makes an excellent agreement with the actual observation, confirming that radial thermal gradients play a key role in activating prismatic slip in 4H-SiC during bulk growth.