Papers by Keyword: Dichlorosilane

Abstract: 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.

Abstract: Application of dichlorosilane (DCS) in 4H-SiC epitaxial growth on 4° off-cut substrates has been studied. The effect of C/Si ratio and N₂ gas flow rate on epilayer properties is investigated in detail. It is found that the C/Si ratio has a significant influence on the growth rate, epilayer surface roughness (step-bunching), conversion of basal plane dislocations (BPDs), and generation of morphological defects and in-grown stacking faults. A wide range of doping concentration from p- to n+ can be controlled in DCS growth. High quality 4° off-cut SiC epilayers are achieved for C/Si=1.3 – 1.8. Addition of N₂ has no obvious influence on growth rate and defect densities. The BPD conversion greater than 99.8% is achieved independent of N doping without any pretreatment.

Abstract: 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.

Abstract: 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.

Abstract: In this work we report the measurement of minority carrier lifetimes using the time resolved photoluminescence technique. It was found that 4H-SiC homo-epilayers grown using chlorine-based precursors have longer carrier lifetimes if used in conjunction with a tantalum carbide coated (TaC-coated) graphite susceptor rather than a SiC-coated graphite susceptor. Longer carrier lifetimes were obtained by optimal combinations of precursor gases and susceptor type. The controllable variation in lifetime from 250 ns to 9.9 s was demonstrated.

Abstract: SiO2 films were prepared by atomic layer deposition (ALD) technique, and their physical and electrical properties were characterized for being applied as a gate insulator of low-temperature polysilicon thin-film transistors. ALD SiO2 films were deposited at 350–400 oC using alternating exposures of SiH2Cl2 and O3/O2, and the characteristics of the deposited films were improved with increasing deposition temperature. The ALD films deposited at 400 oC exhibited integrity, surface roughness and leakage current better than those of the conventional plasma-enhanced chemical vapor deposition (PECVD) films.