Raman scattering experiments were carried out on Si∕SiGe heterostructures. The strain in both the top Si layer, and Si1−xGex buffer layers with various Ge compositions was evaluated using several excitation sources, together x-ray diffraction secondary ion mass spectrometry. strain-shift coefficient, which is a necessary quantity to evaluate by spectroscopy, precisely determined. dependence of Si–Si band frequency composition SiGe alloy also examined. We found that strained top-Si thickness...

Recent development of device fabrication SiC is awaiting detailed study the machining surfaces. We scratched 4H-SiC surfaces with a sliding microindenter made chip, and characterized affected layers by micro-Raman spectroscopy. The results Raman measurement scratching grooves revealed that there were residual stress, defects, stacking faults. Furthermore, heavy load, we found clusters amorphous SiC, Si, carbon, graphite in grooves. Analysis spectra showed amorphization occurs first surface...

Micro-Raman imaging measurements of $n$-type $4H\text{\ensuremath{-}}\mathrm{Si}\mathrm{C}$ crystals with graded donor concentration were carried out, and spatial distributions the free carrier concentration, mobility, longitudinal optical (LO) phonon damping obtained from a line shape analysis LO phonon-plasmon coupled (LOPC) mode. The carriers optic phonons was determined as function density. We an empirical relationship between relative Raman shift LOPC mode, which is in close agreement...

Multiple energy phosphorous ions were implanted into 4H-SiC at room temperature and an elevated (500 °C) followed by annealing various temperatures. Deep ultraviolet Raman microscopy was used to analyze the effect of implantation dose postannealing on recovery surface layers damaged implantation. The analysis showed that rate crystallinity increased with increase in temperature. However, for highly dosed samples, not complete even temperatures up 1700 °C. With room-temperature implantation,...

For n-type 4H-SiC crystals with carrier concentrations between 2 × 1017 and 2.5 1020 cm−3, Fano interference of the folded transverse acoustic (FTA) doublet modes was observed. The line-shape parameters were shown to vary concentration. It is proposed that peak shifts in FTA resulting from an electronic continuum state can be used measure concentration for up cm−3. In addition, relative intensity varies markedly above 5 1018 This suggests mode coupling occurs components. variation ratio...

The formation of parasitic SiC inclusions was completely suppressed during solution growth using an liner crucible that provided conditions saturated only with SiC. In contrast, formed in a graphite as carbon source. For crucible, the frequency increased Cr content solvent, which ascribed to increasing C solubility. dissolution behavior crucibles containing Si–Cr solvents investigated; we found thickness Si–SiC–C composite layer on wall decreased solvent and disappeared for higher than 40...

Nanoscale understanding of high-temperature crystal growth dynamics in solution has been a challenge to be tackled by many researchers engaged investigating processes for bulk single growth. Here we propose new approach situ observation at buried solid/liquid interface using conventional confocal laser scanning microscope. In the 4H-SiC with Si–Ni based alloy flux as model system, show ability quantitatively analyze step motions growing SiC on nanoscale high temperatures up 1700 °C vacuum....

We have investigated growth rate and surface morphology of 4H-SiC single crystal grown from Si-C solution with various supersaturation levels at temperature in the range 1840 to 2140 °C. The depends linearly on amount supersaturated carbon, irrespective temperature. This indicates that is limited by transfer solute element onto crystallization front. adequate condition for stable are discussed respect high morphology.

We have investigated the solution growth under various Al-N co-doping conditions. Both p-type and n-type 4H-SiC were successfully grown conditions, while using effect of Al-addition to stabilize both surface polytype. The doping electrical properties systematically. Interaction between Al N in incorporation process property heavily co-doped conditions discussed.

Propagation of threading screw dislocations (TSDs) during hybrid growth, combined with TSD conversion by solution growth and bulk physical vapor transport, has been investigated for 4° off 15° C-face seeds. The converted defects on basal planes (BP-defects) are able to be eliminated continuing guide them a seed, while BP-defects revert TSDs seed. difference in the propagation is discussed based elastic energy balance between unit thickness higher off-angle

Cross-sectional CL measurements have been performed on the cleaved surface of Al-ion implanted 4H-SiC. The strong L1 luminescence that originates from DI defect has observed even in deep region (~10 μm) where ions do not penetrate. In layer, results show high-density non-radiative defects remain after activation annealing. Generation is presumably attributed to diffusion point layer.

We have investigated Raman spectra of p-type 4H-SiC crystals with hole concentration ranging from 3×10 16 to 1×10 21 cm -3 . For folded transverse acoustic (FTA) doublet modes, Fano interference profiles were analyzed, and the frequency shift due was obtained as a function concentration. demonstrated that FTA modes is quantitative measure for evaluating 4H-SiC. Spectral features optical (TO) longitudinal phonon-plasmon coupled (LOPC) also studied various carrier concentrations. The results...

We have developed the bulk growth technique to reduce threading screw dislocations (TSDs) by combining solution and PVT methods. More than 80 % of TSDs in original seed crystals were successfully converted Frank defects on basal planes 4° off C-face with Si-5at.% Ti solvent. After as-grown surface conversion layer, reduced. The presence micrometer-size macrosteps initial stage is important continue propagate during growth.

Abstract The Raman scattering spectra of CdGa 2 Se 4 under pressure were investigated at 300 K up to 20.9 GPa. TO as well LO modes observed. Two stages observed in the dependences bands. Such a behaviour was attributed ordedisorder phase transition cation sublattice. A first‐order 20.2 Using HarrisoKeating model lattice dynamics modified for crystals with tetragonal structure, bulk modulus B and mode‐Grüneisen parameters Γ i determined first time. It is shown that better agreement between...

We have reported depth and in-plane profiling of strain, Ge composition, defects in strained-Si∕Si1−xGex∕Si heterostructures using micro-Raman imaging. Raman the direction was carried out with a resolution ∼15nm small-angle beveled sample ultraviolet (UV) excitation. Depth profiles composition bandwidth clearly show that defect density depends strongly on Ge-grading rate compositionally graded Si1−xGex layer. The strain variation at given each layer has been evaluated. variations are closely...

We have investigated polishing-induced surface damage in nitrogen-doped {0001} 4H-SiC crystals with silicon and carbon faces through deep ultraviolet Raman microspectroscopy. The structural electrical properties of the damaged layers were characterized as a function abrasive particle size, using pure phonon modes longitudinal-optical-phonon plasmon coupled mode monitor bands. degree decreased size. Although polishing finer particles enables long-range order lattice to almost fully recover,...