Annealing studies of AlN capped, MOCVD grown GaN films

• Published in: Solid-state electronics Vol. 101; pp. 23 - 28
• Main Authors: Derenge, Michael A., Kirchner, Kevin W., Jones, Kenneth A., Suvarna, Puneet, Shahedipour-Sandvik, Shadi
• Format: Journal Article Conference Proceeding
• Language: English
• Published: Kidlington Elsevier Ltd 01.11.2014; Elsevier
• Subjects: AlN; Anneal cap; Applied sciences; Chemical vapor deposition (including plasma-enhanced cvd, mocvd, etc.); Cross-disciplinary physics: materials science; rheology; Electronics; Exact sciences and technology; GaN; Materials science; Methods of deposition of films and coatings; film growth and epitaxy; Microelectronic fabrication (materials and surfaces technology); Physics; Semiconductor electronics. Microelectronics. Optoelectronics. Solid state devices; GaN; Anneal cap; AlN; Aluminium oxide; Binary compound; Annealing; Vacancy; Charge carrier density; Point defect; Aluminium nitride; Chemical vapor deposition; MOCVD; Gallium nitride; III-V compound; Microelectronic fabrication; Etch pit; III-VI compound; Rocking curve; Electron mobility; Computer aid
• ISSN: 0038-1101; 1879-2405
• DOI: 10.1016/j.sse.2014.06.027

•We developed an AlN capping process to anneal C-plane GaN up to 1300°C for 30min.•AFM roughness increases in GaN when annealed at 1200–1300°C for 30min.•XRD rocking curves showed decrease in FWHM of GaN after annealing.•Changes in XRD FWHM and film bow suggest that film became more relaxed during anneal. An AlN annealing cap has been developed for GaN films grown on sapphire substrates that enables them to be annealed at temperatures as high as 1300°C for times as long as 30min or times as long as 120min at a temperature of 1150°C without creating a significant number of electrically active N vacancies or new thermal etch pits due to the preferential evaporation of N. However, the pits in the as-grown sample became larger and their sidewalls became steeper, and the flat areas of the film became a little rougher when the annealing time and/or temperature was larger. The films became more relaxed as indicated by a >10% reduction in the X-ray rocking curve peak widths and the creation of a more uniform convex bow. Both the net carrier concentration and electron mobility were reduced by the anneal suggesting that compensating point defects had been created. One possible explanation is that more C in these metal organic chemical vapor deposition (MOCVD) grown films occupied N sites where it is believed to be a deep acceptor.