SiC epitaxial films grown in an inverted chimney CVD reactor using silane-propane-hydrogen and dichlorosilane (DCS)-propane-hydrogen systems are compared for growth rates and doping concentrations at various growth pressures. Parasitic depositions in the gas injector tube using these precursor gases are also compared for precursor depletion. Virtual Reactor, a commercial software, is employed to predict growth rates and compare them to experimental results for the same growth conditions using DCS and silane gases.
Formation of particles and their effect on SiC epitaxial growth in the CVD reactor is investigated. Particle induced defects in the epilayer at different gas decomposition conditions are discussed. A higher number of pits with larger diameters are observed in the epilayer for conditions where gases decompose later in the gas injector tube (i.e. nearer to the substrate). On the other hand, the number and size of these pits reduce for the condition where gas decomposes earlier in the tube. To investigate the effect of particles during the growth, various particles with different size, shape and compositions are intentionally placed on the substrate surface before epitaxial films are grown. Samples are mapped and compared at similar locations in the pre-growth, post growth and post-etch (by molten KOH) conditions. It is found that the nature of particle induced defects depends primarily on size and shape of particles.
Room temperature photoluminescence was obtained by UV excitation of homoepitaxially grown 4H-SiC thin films. A broad band emission from boron deep levels centered at 517nm was observed along with the band-edge emission of 4H-SiC at 391 nm. The wavelength of the excitation was varied and the change in the relative intensity of the two emission peaks was observed. The variation of the relative intensity was correlated with the in-grown stacking fault density in the epilayer. A physical model was developed to explain the correlation in terms of carrier diffusion length. For epilayers with very high density of in-grown stacking faults, a sharp emission was observed at 480nm.
This paper presents one of the first comparative studies of distinctive results obtained using halogenated silicon precursors, dichlorosilane (SiH2Cl2, DCS) and tetrafluorosilane (SiF4, TFS) for SiC homo epitaxial growth. Both TFS and DCS possess very distinct properties that show specific influence on SiC growth. SiC epitaxial growth using TFS greatly suppresses parasitic deposition in the gas delivery system. Growth using TFS shows carbon mediated growth regime, and exhibits controlled doping concentration of the epilayer by an order of magnitude lower than that in the growth using DCS at the same C/Si ratio. Studies of epilayer surface morphology show that the epilayers from TFS growth have a specular surface in a wide C/Si range whereas in the growth using DCS, the epilayer surface roughness is strongly dependent on the C/Si ratio.
In-grown stacking faults (IGSFs) were studied in 4H-SiC homoepitaxial growth from a SiH2Cl2-C3H8-H2 system. Most of the IGSFs, start from the epilayer/substrate interface, and exhibit photoluminescence emission peak at 2.58 eV (480 nm) indicating of 8H polytype. The growth parameters, including growth temperature, growth pressure, growth rate, hydrogen etching, et al., varied around the regular growth condition do not show a significant effect on the IGSF generation. Reactor furniture is identified to be a major reason of IGSF formation, especially when the insulation part of the furnace is not completely isolated from the growth zone. Dusting of insulation material is crucial in the formation of IGSFs. When using graphite felt as the insulation material, the IGSF density in the epilayer can be as high at ~104 cm-2. Improvement of the insulation material by using graphite foil reduces the density to 30-100 cm-2. Further reduction of IGSF density to less than 10 cm-2 is achieved by mild pretreatment of the substrate in molten KOH-NaOH eutectic.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.