Effects Of A Buffer Layer On The Hetero-epi-growth Of SiCGe On 6H-SiC

Silicon carbide (SiC) is a promising semiconductor with wide band-gap, high saturation electron drift velocity, high thermal conductivity and high breakdown electric field. However, its insensitivity to visible or near infrared light greatly limits its application in optoelectronics. By changing composition ratio of SiCGe ternary alloy can change its band gap to meet the needs in opto- electronic applications. Growth of SiCGe ternary alloy film on 6H-SiC in a conventional hot-wall CVD system is originally studied in our group. Quality of the alloy is greatly impacted by the lattice mismatch between the two materials. Howevere, 3C-SiC matches SiCGe with a proper composition ratio very well. Therefore, a 3C-SiC buffer layer technology is to be employed to improve the growth quality of SiCGe on 6H-SiC.We primarily do these work:1.In growth of SiC film, we studied some factors which effect the quality of buffer layer, these are temperatures of substrates, reaction gas flux, gas pressure when growing SiC film, process of temperature declining. we studied the buffer layer crystal structure by means of small angle X-ray diffraction(SAXRD). Optimized buffer layer preparation process .2.Observed surface morphologies of buffer layers grown under different time by means of SEM firstly . As growing time become longer than a certain time, the roughness of buffer layer gets bigger. Then, observed surface morphologies of SiCGe ternary alloy film grown on buffer layers. It has been shown that use of a buffer layer can improve the growth quality of the SiCGe ternary alloy to some extent. If buffer layer is too thin, it can not absorb the lattice mismatch tress greatly between the film and the substrate, that is it can not improve quality of the SiCGe ternary alloy effectively; If buffer layer is too thick, its surface gets rougher and makes growing SiCGe ternary alloy mono-crystalline film on buffer layers more difficult.