Structural research of monocrystalline silicon carbide and epitaxial layers with special consideration of quantitative analysis of crystal defects

Aim of project
A factor which limits the use of SiC is relatively easy defect formation. Defects specific for SiC, which destroy the electronic structure if they are in the active area, are micropipes. Most of them are, according to Frank’s theory, thermally etched areas of elongated screw dislocations of high Burgers vectors. Moreover, micropipes in SiC wafer, used as a wafer of epitaxial layers, permeate to them during growth and are the cause of defects and even failures of devices. Therefore, elaboration of technology of obtaining monocrystals of silicon carbide of micropipe density below 100/cm2 is a condition of widespread use of SiC for electronic devices. Apart from micropipes in monocrystalline SiC, there are also defects like dislocation, disarrangements etc. The fi rst scientifi c aim (and application) of the project is to study the dependence between formation of structural defects in monocrystalline silicon carbide and parameters of PVT (Physical Vapor Transport).

A good quality thin layer can be obtained mostly in case of homoepitaxy, i.e. a system of small lattice unfi tting. Apart from this, the main quality factor is the degree of defect of the matrix from which the epitaxial layer “copies” structural defects. Changing growth parameters of layers of silicon carbide, such as C/ Si ratio, temperature, pressure, amount of additive, one can obtain 4H-SiC layers in terms of addition on n and p of conductivity 1014–1020. Another aim of the project is structural characterization of chosen epitaxial layers (CVD method) on monocrystalline silicon carbide with special consideration of quantitative characterization of structural defects.

Expected results D
etermination of correlation between defect formation of the mono-SiC (H-hexagonal type) structure and technological parameters of monocrystal formation, which is the key to obtaining structurally good epitaxial layers produced using the CVD method (Chemical Vapor Deposition).

Determination of the number and type of defects in epitaxial layers and an attempt at evaluating their influence on electrical parameters of devices built on the basis of SiC.