In-situ measurements of the critical thickness for strain relaxation in AlGaN/GaN heterostructures.

Journal Article · Tue Jun 01 00:00:00 EDT 2004 · Proposed for publication in Applied Physics Letters.

OSTI ID:959105

Koleske, Daniel David; Mahajan, S ^[1]; Lee, Stephen Roger; Waldrip, Karen Elizabeth; Wise, A T ^[1]; Cross, Karen Charlene; Floro, Jerrold Anthony

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1. Arizona State University, Tempe, AZ

Using in situ wafer-curvature measurements of thin-film stress, we determine the critical thickness for strain relaxation in Al{sub x}Ga{sub 1-x}N/GaN heterostructures with 0.14 {le} x {le} 1. The surface morphology of selected films is examined by atomic force microscopy. Comparison of these measurements with critical-thickness models for brittle fracture and dislocation glide suggests that the onset of strain relaxation occurs by surface fracture for all compositions. Misfit-dislocations follow initial fracture, with slip-system selection occurring under the influence of composition-dependent changes in surface morphology.

• Research Organization: Sandia National Laboratories
• Sponsoring Organization: USDOE
• DOE Contract Number: AC04-94AL85000
• OSTI ID: 959105
• Report Number(s): SAND2004-2963J
• Journal Information: Proposed for publication in Applied Physics Letters., Journal Name: Proposed for publication in Applied Physics Letters.
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
ALUMINIUM NITRIDES
ATOMIC FORCE MICROSCOPY
DISLOCATIONS
FRACTURES
GALLIUM NITRIDES
MORPHOLOGY
STRESS RELAXATION
SURFACE PROPERTIES
THIN FILMS