Control of two-dimensional growth of AlN and high Al-content AlGaN-based MQWs for deep-UV LEDs

Abstract

Dense and atomically flat AlN film with root-mean-square roughness value of 0.32 nm was grown on sapphire substrate at a relatively lower temperature by using a three-step epitaxy technique. On the basis of this AlN template, AlGaN-based multiple quantum wells (MQWs) with atomically flat hetero-interfaces were epitaxially grown to suppress nonradiative recombination by introducing In as a surfactant during simultaneous source supply. As a result, single intense- and narrow-peaked photoluminescence was obtained from the MQWs. Finally, the deep ultraviolet light emitting diodes with well-behaved I-V characteristic and strong electroluminescence in the range of 256–312 nm were fabricated successfully

Effect of fluctuation in Al incorporation on the microstructure, bond lengths, and surface properties of an Al x Ga1−x N epitaxial layer

“…So far, the crystal quality and optical properties of AlGaN epilayers and their relationship with growth parameters, such as substrate temperature, precursor flow rates, and dopants employed, have been studied by many researchers using photoluminescence (PL) spectroscopy, atomic force microscopy (AFM), and scanning electron microscopy (SEM). [7][8][9] However, many fundamental issues, such as lattice deformation, local electronic structure, and coordination number (CN) as well as the Ga-N, Ga-Ga, and Ga-Al bond lengths of AlGaN epilayers, especially those with Al contents greater than 50%, remain unknown. [10,11] In this study, the lattice deformation, surface chemical properties, and local electronic structures of AlGaN epilayers with various Al contents are systematically investigated using X-ray diffraction (XRD), Raman, X-ray photoelectron (XPS), and extended X-ray absorption fine structure (EXAFS) spectroscopy.…”

Growth Temperature Dependency of High Al Content AlGaN Epilayers on AlN/Al2O3 Templates

“…TMAl, trimethylgallium (TMGa) and NH 3 were used as precursors of Al, Ga, and N sources, respectively. Trimethylindium (TMIn) was used as a surfactant to increase the surface mobility of aluminum adatoms as studied previously [12][13]. Before start the growth, sapphire substrates were thermally desorbed at 1150 °C for 10 minutes under H 2 ambient to remove surface contamination and adsorbed water.…”

Effect of Al Addition on Crystal Structure of AlGaN/GaN on GaAs (001) Substrate Grown by Metalorganic Vapor Phase Epitaxy

“…In the literature, there are a considerable number of studies on bandgap engineering and structural modifications of materials with Al substitution [4][5][6]. For group III-Nitride semiconductors, the Al element is contained in the ternary or quaternary alloys, e.g., AlGaN, AlGaInN, for making the quantum well structure with a desirable bandgap [7] or tailoring bandgap for designing high-efficiency and high-brightness white light-emitting diodes (LEDs) [8]. In carbon-based materials, Aldoping provides superior improvement of adsorption capacity for drug delivery function due to its lowest binding energy, as well as enhance the non-linear optical properties, e.g., dipole moment, mean static polarizability and anisotropic polarizability.…”