Skip to main content Accessibility help
×
Home

Layer Thickness Dependence of Strain in GaN grown by HVPE

  • Gyu Gwang Sim (a1), P. W. Yu (a1), D. C. Reynolds (a2), D. C. Look (a2), Sang Soo Kim (a3) and D.Y. Noh (a3)...

Abstract

Wurzite GaN epilayers on sapphire substrates usually suffer from biaxial compressive strain due to the mismatches of the thermal expansion coefficients and the lattice constants between GaN layers and sapphire substrates. We have investigated the layer thickness effects on strain and transition energies by photoluminescence (PL), photoreflectance (PR) and X-ray diffraction (XRD). Samples used in this study are grown by hydride vapor phase epitaxy (HVPE) and have the layer thickness of 0.76, 2.6, 5.3 and 48 m. The PL and PR spectra showed the redshift of the transition energies with increasing layer thickness. This is attributed to strain-induced energy shift. The layer thickness dependence of strains is directly observed by XRD. The strain along the c -axis (εzz) decreased with increasing layer thickness. This indicates the strain is relaxed with layer thickness. From strain variation with layer thickness, we suggest that strain relaxation process is rapid at the initial stage of growth and becomes slower as the layer grows. The full width at half maximum (FWHM) of PL spectra and theta rocking curves decrease with increasing layer thickness. This indicates the crystal quality improves as the strain is reduced. Since the strain effect is very small at the layer thickness of 48 μm, we expect zero strain for thicker layers that can potentially be used as substrates for homoepitaxy.

Copyright

References

Hide All
1. Shikanai, Amane, Azuhata, Takashi, Sota, Takayuki, Chichibu, Shigefusa, Kuramata, Akito, Horino, Kazuhiko and Nakamura, Shuji, J. Appl. Phys. 81, 417 (1997).
2. Jayapalan, J., Skromme, B. J., Vaudo, R. P. and Phanse, V. M., Appl. Phys. Lett. 73, 1188 (1998).
3. Reynolds, D. C., Look, D. C., Jogai, B., Hoelscher, J. E., Sherriff, R. E. and Molnar, R. J., J. Appl. Phys. 88, 1460 (2000).
4. Aspnes, D. E., Surf. Sci. 37, 418 (1973).
5. Leszczynski, M., Teisseyre, H., Suski, T., Grzegory, I., Bockowski, M., Jun, J., Porowski, S., Pakula, K., Baranowski, J. M., Foxon, C. T. and Cheng, T. S., Appl. Phys. Lett. 69, 73 (1996).

Related content

Powered by UNSILO

Layer Thickness Dependence of Strain in GaN grown by HVPE

  • Gyu Gwang Sim (a1), P. W. Yu (a1), D. C. Reynolds (a2), D. C. Look (a2), Sang Soo Kim (a3) and D.Y. Noh (a3)...

Metrics

Full text views

Total number of HTML views: 0
Total number of PDF views: 0 *
Loading metrics...

Abstract views

Total abstract views: 0 *
Loading metrics...

* Views captured on Cambridge Core between <date>. This data will be updated every 24 hours.

Usage data cannot currently be displayed.