Jiang Teng

Comparative Study of the Characteristics of the Basal Plane Stacking Faults of Nonpolar a −Plane and Semipolar (11<span style=

Nonpolar (112?0) and semipolar (112?2) GaN are grown on r-plane and m-plane sapphire by MOCVD to investigate the characteristics of basal plane stacking faults (BSFs). Transmission electron microscopy reveals that the density of BSFs for the semipolar (112?2) and nonpolar a-plane GaN template is 3?105 cm?1 and 8?105 cm?1, respectively. The semipolar (112?2) GaN shows an arrowhead-like structure, and the nonpolar a-plane GaN has a much smoother morphology with a streak along the c-axis. Both nonpolar (112?0) and semipolar (112?2) GaN have very strong BSF luminescence due to the optically active character of the BSFs.

Growth of a-Plane GaN Films on r-Plane Sapphire by Combining Metal Organic Vapor Phase Epitaxy with the Hydride Vapor Phase Epitaxy*

Hydride vapor phase epitaxy (HVPE) is utilized to grow nonpolar a-plane GaN layers on r-plane sapphire templates prepared by metal organic vapor phase epitaxy (MOVPE). The surface morphology and microstructures of the samples are characterized by atomic force microscopy. The full width at half maximum (FWHM) of the HVPE sample shows a W-shape and that of the MOVPE sample shows an M-shape plane with the degree of in the high-resolution x-ray diffraction (HRXRD) results. The surface morphology attributes to this significant anisotropic. HRXRD reveals that there is a significant reduction in the FWHM, both on-axis and off-axis for HVPE GaN are compared with the MOVPE template. The decrease of the FWHM of E2 (high) Raman scattering spectra further indicates the improvement of crystal quality after HVPE. By comparing the results of secondary-ion-mass spectroscope and photoluminescence spectrum of the samples grown by HVPE and MOVPE, we propose that C-involved defects are originally responsible for the yellow luminescence.

Morphological and Microstructural Evolution and Related Impurity Incorporation in Non-Polar a -Plane GaN Grown on r-Sapphire Substrates

Effects of the growth temperature on morphological and microstructural evolution of a-plane GaN films grown on r-plane sapphires by metal organic chemical vapor deposition are investigated by atomic force microscopy and secondary ion mass spectroscopy (SIMS). Surface morphology, structural quality and related impurity incorporation are very sensitive to the growth temperature. A significant difference of yellow luminescence is observed and attributed to the incorporation of carbon into GaN films, which is confirmed by SIMS analysis. Our results show that the sample with triangular-pit morphology has significantly higher concentrations of oxygen than the other sample with pentagon-like pit morphology, which is induced by the existence of an N-face in triangular pits.