Combined use of in-situ curvature and full- wafer ... - Laytec

Motivation
A potential low-cost manufacturing route for GaN based solid-state lighting
Advantages:
Issues:
� Availability of large size substrates at lower cost
� Much lower fabrication costs of the devices
� Compatibility with standard Si processing equipment
� Higher thermal conductivity than sapphire
� Possibility of vertical contact LEDs on conducting silicon
� Possibility of integrating electronics and optical devices
� Large thermal expansion mismatch (Si: 54% that of GaN)
� Large lattice mismatch (lattice constant Si: 17% less than GaN)
Resulting in:
� Tensile strain and high dislocation density in epitaxial GaN
� Wafer bowing and/or cracking, making processing difficult
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