Dislocation arrangement in a thick LEO GaN film on sapphire[Lateral Epitaxial Overgrowth]

Conference · Sat Jul 01 04:00:00 EDT 2000

OSTI ID:20104528

Dunn, K A; Babcock, S E; Stone, D S; Matyi, R J; Zhang, L; Kuech, T F

Diffraction-contrast TEM, focused probe electron diffraction, and high-resolution X-ray diffraction were used to characterize the dislocation arrangements in a 16{micro}m thick coalesced GaN film grown by MOVPE LEO. As is commonly observed, the threading dislocations that are duplicated from the template above the window bend toward (0001). At the coalescence plane they bend back to lie along [0001] and thread to the surface. In addition, three other sets of dislocations were observed. The first set consists of a wall of parallel dislocations lying in the coalescence plane and nearly parallel to the substrate, with Burgers vector (b) in the (0001) plane. The second set is comprised of rectangular loops with b = 1/3 [11 {bar 2}{bar 0}] (perpendicular to the coalescence boundary) which originate in the coalescence boundary and extend laterally into the film on the [1 {bar 1}00] bar axis with 1/3<11 {bar 2}0>-type Burgers vectors. These sets result in a dislocation density of {approximately}10{sup 9} cm{sup {minus}2}. High resolution X-ray reciprocal space maps indicate wing tilt of {approximately}0.5{degree}.

• Research Organization: Univ. of Wisconsin, Madison, WI (US)
• Sponsoring Organization: Office of Naval Research; National Science Foundation
• OSTI ID: 20104528
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
DIFFRACTION
DISLOCATIONS
ELECTRON MICROSCOPY
EXPERIMENTAL DATA
GALLIUM NITRIDES
MICROSTRUCTURE
THIN FILMS