Selected Energy Epitaxial Deposition and Low Energy Electron Microscopy of AlN, GaN and SiC Thin Films
Abstract
In situ real-time low energy electron microscopy of GaN homoepitaxial growth using supersonic jets was conducted. Non-faceted basal-plane GaN(0001) layers were successfully grown when the GaN/NH3 flux ratios exceeded two in the temperature range of 660-710 deg C. Very smooth layers with atomic steps were obtained when growth occurred on regions of the substrate surface previously covered by Ga liquid droplets. This effect is believed to be due to the etching of the GaN substrate surface by the excess Ga, exposing screw dislocations of nucleation and producing an impurity-free surface for growth. Growth of smooth GaN films in the Ga-stable growth regime using an NH3-seeded supersonic molecular beam was also accomplished. A GaN film grown at 700 deg C using 0.6eV NH3 exhibited a RMS roughness of 3.9 nm, as evidenced by atomic force microscopy. Plots of GaN growth rate versus NH3 flow and Ga flux were used to determine the Ga/N ratio needed for non-faceted growth. Increasing the NH3 kinetic energy from 0.25 to 0.41 eV had no effect on growth rate or film morphology for films grown under N-stable conditions. Preliminary results indicate that increasing the NH3 kinetic energy from 0.45 to 0.73 eV did not change the growth rate under Ga-stable conditions, but the surface morphology was improved. Initial cleaning results using a 1.1 eV Kr beam and Ga flux cleaning at 700 deg C are presented. Future work will include testing of a supersonic N atom source and SEED of AlN on 6H-SiC.
Document Details
- Document Type
- Technical Report
- Publication Date
- Dec 01, 1998
- Accession Number
- ADA359150
Entities
People
- H. Henry Lamb
- I. S. Tsong
- Robert F Davis
Organizations
- North Carolina State University