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2 Prace Naukowe Politechniki Warszawskiej. Elektronika

2 1999

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Structural and optical properties of GaN/ESiC/Si heterostructures grown by MBE

Skibarko I., Milchanin O., Gaiduk P., Komarov F., Marks J., Pastuszka B., Iller A., Diduszko R.

Prace Naukowe Politechniki Warszawskiej. Elektronika

1999

z. 123

49-54

We have investigated structural and optical properties of cubic GaN (beta-GaN) layers grown on SiC/Si(001) substrates by electron cyclotron resonance assisted molecular beam epitaxy (ECR-MBE) using several methods (RHEED, TEM, AFM, XRD, PL). The about 50 nm thick beta-SiC layers were formed firstly by the thermal annealing of Si(OO1) wafers in vacuum at initial pressure 1x10(-5) mbar. Then the GaN layers have been grown on SiC/Si structures with the growth ratę of 50-60 nm/h. It is established that GaN growth takes place in the three-dimensional mode and the final GaN layers are preferably of cubic orientation. The fraction of included hexagonal GaN phase is found to be negligible. The PL spectra of 250 mn thick beta-GaN exhibit emission in both blue and yellow ranges.

Effect of cavities in Si-substrate on heteroepitaxial growth of Si(sub 0.85)Ge(sub 0.15) alloys

Gaiduk P., Nylandsted A., Lundsgaard H., Komarov F.

Prace Naukowe Politechniki Warszawskiej. Elektronika

1999

z. 123

55-59

A method of Si quasi-membrane formation for MBE growth of dislocation-free relaxed Si(0.85)Ge(0.15) alloy layers on Si substrate is presented. The Si quasi-membrane is formed by hydrogen im-plantation followed by thermal treatment which result in the formation of void-containing buffer layer that makes Si-Si bonds weaker. The effects of voids on the MBE growth of Si(0.85) Ge(0.15) alloy layers and the formation of misfit dislocations and their glissile arms - threading dislocations arę investigated and documented. It is found that the relaxation of strains in SiGe/Si layers is more enhanced in the case of the growth at void-containing substrate. A good share of threading arms run into the substrate and in this way the reduction of threading dislocations in the surface layer can be explained.