Stress relaxation in GaN by transfer bonding on Si substrates

Abstract

The stress state of GaN epilayers transferred onto Si substrates through a Au–Si bonding process was studied by micro-Raman scattering and photoluminescence techniques. By increasing the Au bonding thickness from 1to40μm, the high compressive stress state in GaN layer was relieved. A 10μm Au bonding layer thickness is shown to possess the maximum compressive stress relief and also the deformation potential of the quantum well was found to be ∼85meV. A nonlinear parabolic relation between luminescent bandgap and the biaxial stress of the transferred GaN epilayer in the compressive region was observed.

InGaN-Based Light Emitting Diodes with an AlN Sacrificial Buffer Layer for Chemical Lift-Off Process

“…The peak wavelength bluehift phenomenon of the lift-off LED epitaxial layer on the adhesive tape could be caused by a compressed strain reduction in the InGaN active layers. A blueshift phenomenon and a broadened line-width of the µ-PL spectrum were measured for the lift-off LED epitaxial layer similar to the one reported by Hsu et al 15 The PL peak wavelengths are almost the same at 451.8nm for the laterally etched mesa region and the lift-off epitaxial layer, both without contact with the sapphire substrate. The PL intensity at the mesa edged region, with a 5µm-diameter laser spot size, was higher than at the lift-off epitaxial layer, because of the light reflected from the separated bottom sapphire substrate without the AlN buffer layer.…”

Phase reaction of Au/Sn solder bonding for GaN-based vertical structure light emitting diodes

“…It is known that large residual stress exists in the chips on the sapphire substrate for the lattice mismatch. If the bonding material is well selected, the VSLEDs will release a lot of residual stress, enhancing devices' properties [17]. Points from the center to the border were selected on the 375 μm×375 μm chips under different bonding conditions, and the stress were measured by Raman scattering.…”

Use of Aluminum-Doped Zinc-Oxide Film as a Strain-Relief and Schottky Blocking Layer for the Fabrication of Vertical Structure Metal Substrate GaN-Based Light-Emitting Diodes

“…I). Thus the intrinsic polarization states are altered, and in turn electroluminescence (EL) characteristics, and irradiative recombination efficiency are affected [5][6][7]. In this work, we managed to alleviate this situation by inserting a sputter-deposited aluminum-doped zinc-oxide (AZO) layer between p-side ohmic contacts (oxidized Ni/Au) and the underlying metal layers for its less mismatching CTE and good as-deposited optical properties [8][9][10].…”