In situ stress measurements during MOCVD growth of AlGaN on SiC

Jeremy D. Acord, Srinivasan Raghavan, David W. Snyder, Joan Marie Redwing

Research output: Contribution to journalArticle

27 Citations (Scopus)

Abstract

Deposition of AlxGa1-xN (x>0.3) for UV devices is challenging due to defect formation and film cracking that are commonly observed in thick layers. Cracking is generally attributed to lattice constant and thermal expansion mismatch between film and substrate, and also between AlGaN layers of different compositions. However, growth-related stresses due to developing film morphology also play a role. In situ stress measurements were used to investigate effects of growth conditions on stress evolution during MOCVD growth of AlGaN on SiC. An initial compressive stress was measured during AlGaN growth on thin AlN buffer layers, which evolved with film thickness into a tensile growth stress. The thickness at which the transition occurred was found to depend on the buffer layer growth conditions and on the AlGaN Al fraction. Increasing the AlN buffer layer V/III ratio from 750 to 10,600 increased the AlGaN initial compressive stress from 1.9 to 8.7 GPa, which reduced the film's final tensile stress. GaN was not observed to transition into tensile growth stress within the 3.8 μm thickness grown, while increasing Al fraction corresponded to a more rapid change into tensile growth. The observed stress evolution is explained in terms of an initial compressive growth stress that changes to a final tensile stress due to morphological evolution during growth.

Original languageEnglish (US)
Pages (from-to)65-71
Number of pages7
JournalJournal of Crystal Growth
Volume272
Issue number1-4 SPEC. ISS.
DOIs
StatePublished - Dec 10 2004

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stress measurement
Stress measurement
Metallorganic chemical vapor deposition
metalorganic chemical vapor deposition
Buffer layers
buffers
tensile stress
Compressive stress
Tensile stress
Ultraviolet devices
aluminum gallium nitride
Lattice constants
Thermal expansion
Film thickness
thermal expansion
film thickness
Defects
expansion

All Science Journal Classification (ASJC) codes

  • Condensed Matter Physics

Cite this

Acord, Jeremy D. ; Raghavan, Srinivasan ; Snyder, David W. ; Redwing, Joan Marie. / In situ stress measurements during MOCVD growth of AlGaN on SiC. In: Journal of Crystal Growth. 2004 ; Vol. 272, No. 1-4 SPEC. ISS. pp. 65-71.
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In situ stress measurements during MOCVD growth of AlGaN on SiC. / Acord, Jeremy D.; Raghavan, Srinivasan; Snyder, David W.; Redwing, Joan Marie.

In: Journal of Crystal Growth, Vol. 272, No. 1-4 SPEC. ISS., 10.12.2004, p. 65-71.

Research output: Contribution to journalArticle

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