Defect Reduction in MBE-Grown AlN by Multicycle Rapid Thermal Annealing

Defect Reduction in MBE-Grown AlN by Multicycle Rapid Thermal Annealing

Multicycle rapid thermal annealing (MRTA) is shown to reduce thedefect density of molecular beam epitaxially grown AlN films. Nodamage to the AlN surface occurred after performing the MRTA processat 1520°C. However, the individual grain structure was altered, with theemergence of step edges. This change in grain structure and diffusion ofAlN resulted in an improvement in the crystalline structure. The RamanE2 linewidth decreased, confirming an improvement in crystal quality. The optical band edge of the AlN maintained the expected value of6.2 eV throughout MRTA annealing, and the band edge sharpened afterMRTA annealing at increased temperatures, providing further evidence ofcrystalline improvement. X-ray diffraction shows a substantial improvementin the (002) and (102) rocking curve FWHM for both the 1400 and1520°C MRTA annealing conditions compared to the as-grown films,indicating that the screw and edge type dislocation densities decreased. Overall, the MRTA post-growth annealing of AlN lowers defect density,and thus will be a key step to improving optoelectronic and powerelectronic devices.

Multicycle rapid thermal annealing (MRTA) is shown to reduce thedefect density of molecular beam epitaxially grown AlN films. Nodamage to the AlN surface occurred after performing the MRTA processat 1520°C. However, the individual grain structure was altered, with theemergence of step edges. This change in grain structure and diffusion ofAlN resulted in an improvement in the crystalline structure. The RamanE2 linewidth decreased, confirming an improvement in crystal quality. The optical band edge of the AlN maintained the expected value of6.2 eV throughout MRTA annealing, and the band edge sharpened afterMRTA annealing at increased temperatures, providing further evidence ofcrystalline improvement. X-ray diffraction shows a substantial improvementin the (002) and (102) rocking curve FWHM for both the 1400 and1520°C MRTA annealing conditions compared to the as-grown films,indicating that the screw and edge type dislocation densities decreased. Overall, the MRTA post-growth annealing of AlN lowers defect density,and thus will be a key step to improving optoelectronic and powerelectronic devices.