Spatially resolved cathodoluminescence of GaN nanostructures fabricated by photoelectrochemical etching

Abstract

The emission properties of GaN nanostructures created by photoelectrochemical etching have been investigated by cathodoluminescence (CL) in the scanning electron microscope. Columnar structures with diameters of 150–250 nm formed near the surface of the as-grown GaN layers branch into nanowires with diameters of 20–60 nm, while islands with coral-like relief were observed at the bottom of the etched areas. CL emission of the observed nanostructures is dominated by free electron to acceptor transitions. Local CL spectra provide direct evidence of the existence of either compressive or tensile stress in different nanostructures. No free exciton luminescence was observed in GaN nanowires, supporting their relation to threading dislocations.

Effect of threading defects on InGaN∕GaN multiple quantum well light emitting diodes

“…Measurement of dislocation density using PEC etching has previously been shown to be entirely consistent with the TD density measured by transmission electron microscopy, 5,6 cathodoluminescence, 7 and photoluminescence. The defect density was accurately determined by counting the number of whiskers within a known area within the mesa of the LED.…”

Microstructural properties and atomic arrangements of GaN nanorods grown on Si (111) substrates by using hydride vapor phase epitaxy

“…Even though some works concerning the formation and optical properties of 1-D GaN nanostructures using HVPE have been performed [17], relatively few studies on the microstructural properties and the atomic arrangements of the GaN nanostructures have been carried out. Because the microstructural properties of the GaN nanostructures significantly affect their electrical and the optical properties, which are necessary for fabricating high-efficiency devices [18,19], studies on the microstructural properties of GaN nanostructures are very important for enhancing nanodevices fabricated utilizing GaN nanostructures. Furthermore, GaN/Si heterostructures are of particular interest in the integration of optoelectronic devices due to the large exciton binding energy of the GaN semiconductors and the cheapness and the large size of Si substrates [20,21].…”

Photoelectrochemical etching measurement of defect density in GaN grown by nanoheteroepitaxy

“…9,10 Minsky et al 11 demonstrated photoelectrochemical ͑PEC͒ etching to characterize dislocations in GaN. Later, dislocation-selective PEC etching that was consistent with transmission electron microscopy 12,13 ͑TEM͒ and cathodoluminescence 14 was reported and correlation between the dislocation density determined by PEC etching and photoluminescence ͑PL͒ intensity were also found. 15,16 We report the application of PEC etching to the determination of dislocation density in Si-doped, NHE GaN coalesced films grown on 6H-SiC substrates by metalorganic chemical vapor deposition ͑MOCVD͒.…”

“…Figure 1 shows the PEC etched surface of the ͑a͒ planar and ͑b͒ NHE GaN samples after 1 m of GaN has been removed. Based on previous analysis, [12][13][14][15][16] the whiskers shown in this figure correspond to threading dislocations. The insets shown in Figs.…”