Figures

Figure 1a

Cross section SEM micrograph of a typical GaN LEO stripe on Si(111) after 60 minutes of growth: sample A, 60 nm-thick AlN.

Figure 1b

Cross section SEM micrograph of a typical GaN LEO stripe on Si(111) after 60 minutes of growth: sample B, 180 nm-thick AlN.

Figure 2a

Surface topography measured by tapping mode AFM: sample A, large-area scan.

Figure 2b

Surface topography measured by tapping mode AFM: sample A, height mode. The "S" arrow indicates an instance of step termination associated with a screw-character threading dislocation intersection the surface of the film. The "E" arrow indicates an instance of a smaller surface depression typically associated with pure edge threading dislocation.

Figure 2c

Surface topography measured by tapping mode AFM: sample B, height mode. "S" and "E" arrows as in Figure 2b.

Figure 3a

Cross section bright-field TEM micrographs of sample A. The left and right panels correspond to g = 110 and g = 0002, respectively. The irregular top and side surfaces are due to the ion milling process.

Figure 3b

Cross section bright-field TEM micrographs of sample B. The left and right panels correspond to g = 110 and g = 0002, respectively. The irregular top and side surfaces are due to the ion milling process.

Figure 4a

X-ray rocking curves of sample A. The dotted (solid) line corresponds to an -scan with the stripe direction parallel (perpendicular) to the diffraction plane.

Figure 4b

X-ray rocking curves of sample B. The dotted (solid) line corresponds to an -scan with the stripe direction parallel (perpendicular) to the diffraction plane.

Figure 5

Room temperature PL spectra of samples A and B. In this experiment the emission from both the LEO and the seed region was collected.

Figure 6

(a) Plan-view SEM micrograph of sample A; (b) monochromatic (=367 nm) CL images of the same region; (c) high magnification image of (b).

© 1999 The Materials Research Society