Crystal growth of wide bandgap semiconductors

Selected results

• Development of an alternative vapour phase growth process    

To solve the limitations related to the usual seeded sublimation process, we have proposed the Continuous Feed Physical Vapor Transport (CF-PVT) technique. It combines the advantages of both the PVT process for the growth of single crystals and HTCVD process for the in-situ formation and continuous feeding of the high purity polycrystalline source. (Cryst. Growth & Design 5 (2005) p.1539, Chem. Vap. Dep. 12 (2006) p.541-548).

• The growth of twin free 3C-SiC thick epilayers                 
  

Heteroepitaxial growth of 3C-SiC layers on (0001) 6H-SiC nominal substrates is systematically facing twin formation. Based on a thorough investigation of the 3C nucleation and growth on 6H-SiC, we have proposed a mechanism for twin elimination that has allowed growing for the first time a twin free 3C-SiC thick layer on a 6H-SiC substrate. (J. Cryst. Growth 275 (2005) p.e609, Cryst. Growth & Design 6 (2006) p.2788).

• Demonstration of 3C-SiC bulk crystal growth (European RTN Project # MRTN- CT-2006-035735)

We have demonstrated for the first time the possibility to growth 3C-SiC crystals under real bulk growth conditions (2100°C, with a rate about 0.8 mm/h) and with outstanding structural quality. Our results call into question again most of the existing literature about the 3C-SiC stability and synthesis conditions (J. Cryst. Growth 310 (2008) p. 976-981, Appl. Phys. Let. 94 (2009) p.201904).

Few millimetres size unseeded 3C-SiC crystals exhibiting perfectly faceted shapes

• Demonstration of high-T SiC solution growth (ANR Contract Nb ANR-05-JCJC-0207-01)

By a coupled approach involving experiments and full process modelling, we have demonstrated the viability of solution growth for SiC single crystal synthesis. This way could be an alternative to sublimation, particularly for the growth of low-temperature polytypes like 3C-SiC and for high-quality crystals. (Mat. Sci. Forum Vols. 615-617 (2009) p. 41). 

Simulation of melt flow and temperature distribution in a tipped crucible. Left side of crucibles: Streamlines of convective flow. Right side of crucibles: Arrows are proportional to modulus of velocity flow

• Quantitative use of birefringence for the study of extended defects

The dislocation-induced birefringence of Silicon Carbide (SiC) is analytically and quantitatively modelled. The birefringence microscopy technique is thus revealed as an interesting tool for probing the nature of the dislocations associated, e.g., to micropipes, also faster than and complementary to the more involved TEM technique or X-ray topography. (Mat. Sci. Forum Vols. 615-617 (2009) p. 271). 

            

 Birefringence images (measured and simulated) on a dislocation lying in a prismatic glide plane of 6H-SiC.