Controlling surface adatom kinetics for improved structural and optical properties of high indium content aluminum indium nitride

• Published in: Journal of applied physics Vol. 127; no. 12
• Main Authors: Engel, Zachary, Clinton, Evan A., Matthews, Christopher M., Doolittle, W. Alan
• Format: Journal Article
• Language: English
• Published: Melville American Institute of Physics 31.03.2020
• Subjects: Adatoms; Aluminum; Applied physics; Atomic force microscopy; Diffusion effects; Emission spectra; Indium; Indium nitride; Kinetics; Low temperature; Optical properties; Phase separation; Photoluminescence; Quantum wires; Spectrum analysis; Surface diffusion; X-ray diffraction
• ISSN: 0021-8979; 1089-7550
• DOI: 10.1063/1.5142295

A non-traditional, for AlInN, method of controlling adatom kinetics and a low temperature growth condition were employed to improve the quality of high indium content aluminum indium nitride films. Metal-rich surfaces were used to enhance adatom mobility and compensate for the low growth temperature (Tsub ≤ 400 °C) effect of reducing surface diffusion lengths. The metal-rich approach resulted in 12 times lower x-ray diffraction full-width at half-maximum rocking curve figures of merit when compared to literature. In addition to promising photoluminescence emission, these results indicate improved structural quality over other reported approaches. AlInN films with ∼70% indium content were characterized via x-ray diffraction, atomic force microscopy, and photoluminescence spectroscopy with each technique indicating an optimal growth temperature of 350 °C. Al0.3In0.7N grown above 400 °C exhibited phase separation and a reduction in quality, while samples grown colder were predominantly single-phase and displayed improved photoluminescence at ∼1.45 eV. The photoluminescence spectra suggest emission from quantum wire-like structures with dimensions ranging from 15 to 18 nm. These low-temperature, metal-rich findings for high indium content AlInN are promising for future long-wavelength III-nitride optical devices.