Growth Mode and Characterization of Si/SiC Heterostructure of Large Lattice-Mismatch

The Si/6H-SiC heterostructure of large lattice mismatch follows domain epitaxy mode, which release most of the lattice-mismatch strain, and the coherent Si epilayers can be grown on 6H-SiC. An interfacial misfit dislocation array is present at the interface that determines the domain’s size. In this chapter, transmission electron microscopy (TEM) and high resolution X-ray diffraction (HRXRD) were employed to reveal in-plane orientation, interface structure and growth mode of the Si/SiC heterostructure. Based on the characterizations, residual lattice mismatch and edge misfit dislocation density at the hetero-interface can be precisely controlled. And these characterization methods are applicable for the heterostructures of large-lattice mismatch, except for the heterostructures with different crystal symmetry on the film and the substrate

Si doping superlattice structure on 6H-SiC(0001)

Si-DSL structures multilayers are prepared on 6H-SiC(0001) successfully. The energy offsets of the n-Si/n-6H-SiC heterojunction in the conduction band and valance band are 0.21eV and 1.65eV, respectively. TEM characterizations of the p/n-Si DSL confirms the epitaxial growth of the Si films with [1-11] preferred orientation and the misfit dislocations with a Burgers vector of 1/3 at the p-Si/n-Si interface. J-V measurements indicate that the heterostructure has apparent rectifying behavior. Under visible illumination with light intensity of 0.6W/cm2, the heterostructure demonstrates significant photoelectric response, and the photocurrent density is 2.1mA/cm2. Non-UV operation of the SiC-based photoelectric device is realized

Effect of impurities on the Raman scattering of 6H-SiC crystals

Raman spectroscopy was applied to different-impurities-doped 6H-SiC crystals. It had been found that the first-order Raman spectra of N-, Al- and B-doped 6H-SiC were shifted to higher frequency when comparing with undoped samples. However, the first-order Raman spectra of V-doped sample was shifted to lower frequency, revealing that there existed low free carrier concentration, which might be induced by the deep energy level effect of V impurity. Meanwhile, the second-order Raman spectra are independent of polytype and impurity type

Photoluminescence in SiCGe thin films grown on 6H-SiC

Intense visible luminescence is observed at room temperature from SiCGe films on 6H-SiC (0 0 0 1) substrate. The PL intensity increases rapidly under the UV laser excitation during the first 2 h. This phenomenon may be explained by an effect similar to the Steabler-Wronski effect in hydrogenated amorphous Silicon. High density of defects such as double phase boundaries and stacking faults are observed by TEM characterization, which produce the quasidefects and accelerate the effect. (C) 2009 Elsevier B.V. All rights reserved

TEM Investigation of Asymmetric Deposition-Driven Crystalline-to-Amorphous Transition in Silicon Nanowires

Controlling the shape and internal strain of nanowires (NWs) is critical for their safe and reliable use and for the exploration of novel functionalities of nanodevices. In this work, transmission electron microscopy was employed to examine bent Si NWs prepared by asymmetric electron-beam evaporation. The asymmetric deposition of Cr caused the formation of nanosized amorphous-Si domains; the non-crystallinity of the Si NWs was controlled by the bending radius. No other intermediate crystalline phase was present during the crystalline-to-amorphous transition, indicating a direct phase transition from the original crystalline phase to the amorphous phase. Moreover, amorphous microstructures caused by compressive stress, such as amorphous Cr domains and boxes, were also observed in the asymmetric Cr layer used to induce bending, and the local non-crystallinity of Cr was lower than that of Si under the same bending radius

First-Principles Calculations on Atomic and Electronic Properties of Ge/4H-SiC Heterojunction

First-principles calculation is employed to investigate atomic and electronic properties of Ge/SiC heterojunction with different Ge orientations. Based on the density functional theory, the work of adhesion, relaxation energy, density of states, and total charge density are calculated. It is shown that Ge(110)/4H-SiC(0001) heterointerface possesses higher adhesion energy than that of Ge(111)/4H-SiC(0001) interface, and hence Ge/4H-SiC(0001) heterojunction with Ge[110] crystalline orientation exhibits more stable characteristics. The relaxation energy of Ge(110)/4H-SiC(0001) heterojunction interface is lower than that of Ge(111)/4H-SiC(0001) interface, indicating that Ge(110)/4H-SiC(0001) interface is easier to form at relative low temperature. The interfacial bonding is analysed using partial density of states and total charge density distribution, and the results show that the bonding is contributed by the Ge-Si bonding