Dislocation mechanisms in the GaN lateral overgrowth by hydride vapor phase epitaxy

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

OSTI ID:20104525

Kuan, T S; Inoki, C K; Hsu, Y; Harris, D L; Zhang, R; Gu, S; Kuech, T F

The authors have carried out a series of lateral epitaxial overgrowths (LEO) of GaN through thin oxide windows by the hydride vapor phase epitaxy (HVPE) technique at different growth temperatures. High lateral growth rate at 1,100 C allows coalescing of neighboring islands into a continuous and flat film, while the lower lateral growth rate at 1,050 C produces triangular-shaped ridges over the growth windows. In either case, threading dislocations bend into laterally grown regions to relax the shear stress developed in the film during growth. In regions close to the mask edge, where the shear stress is highest, dislocations interact and multiply into arrays of edge dislocations lying parallel to the growth window. This multiplication and pileup of dislocations cause a large-angle tilting of the laterally grown regions. The tilt angle is high ({approximately}8 degrees) when the growth is at 1,050 C and becomes smaller (3--5 degrees) at 1,100 C. At the coalescence of growth facets, a tilt-type grain boundary is formed. During the high-temperature lateral growth, the tensile stress in the GaN seed layer and the thermal stress from the mask layer both contribute to a high shear stress at the growth facets. Finite element stress simulations suggest that this shear stress may be sufficient to cause the observed excessive dislocation activities and tilting of LEO regions at high growth temperatures.

• Research Organization: State Univ. of New York, Albany, NY (US)
• OSTI ID: 20104525
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
DATA
DISLOCATIONS
GALLIUM NITRIDES
MICROSTRUCTURE
STRESSES
TEMPERATURE DEPENDENCE
THIN FILMS
VAPOR PHASE EPITAXY