High-quality AlN grown on a thermally decomposed sapphire surface

UVA and UVB light emitting diodes with Al y Ga1−y N quantum dot active regions covering the 305–335 nm range

“…In fact, compared to the GaN/(In,Ga)N system, a much stronger impact of dislocations on the quantum well (QW) RE in the (Al,Ga)N/(Al)GaN system is found and attributed, at least partly, to a weaker in-plane spatial localization of excitons than is typically observed in (In,Ga)N QWs [6]. To reduce the DDs in Al x Ga 1-x N layers, epitaxial processes such as the lateral overgrowth method [7], patterned or thermally decomposed sapphire surface [8,9], high temperature annealing [10,11] are being developed, leading to important reduction of DDs down to the 10 8 cm -2 range. Another possibility is to increase the spatial localization of excitons by fabricating three dimensional (3D) confining potentials, i.e.…”

The stability of graphene and boron nitride for III-nitride epitaxy and post-growth exfoliation

“…The voids were commonly observed on Al 2 O 3 and AlN from 1200 and 1300 C, respectively, and the void size increased along with the annealing temperature, which implies that voids were generated by substrate decomposition. 32,35,36 Moreover, as shown in Fig. S7, † the depth of the voids was also increased with elevated annealing temperature aer the onset of AlN decomposition.…”

The Impact of AlN Templates on Strain Relaxation Mechanisms during the MOVPE Growth of UVB‐LED Structures

“…The near‐surface region of the AlN template, the homoepitaxial AlN, the AlN/GaN SL, and the bottom of the Al 0.75 Ga 0.25 N buffer layer are visible. This ADF STEM image was obtained in the [11–20] AlN viewing direction and shows all dislocation types formed in the sample.…”

“…Exemplary cross‐sectional images of lower part of UVB‐LED structure on AlN template with TDD of (4 ± 0.2) × 10 9 cm −2 : a) ADF STEM showing formation of horizontal dislocation lines in AlN/GaN superlattice and strong TD inclination in subsequently grown AlGaN (viewed in [11‐20]AlN projection). b,c) Dark‐field diffraction contrast images of the same specimen area visualizing different types of defects (white arrows indicate the same specimen positions).…”

“…Templates with 1500 nm thick AlN were grown at elevated temperature [ 14,15 ] in a multiwafer reactor on a 430 µm thick sapphire substrate off‐oriented by 0.2° and a 0.5° to sapphire m‐plane. [ 16 ] These AlN base layers show typical full width at half maximum of X‐ray rocking curves (XRC‐FWHM) of ≈ (60 ± 5) arcsec for the (00.2) reflection for both off‐cut angles.…”