Fabrication of thin-film InGaN light-emitting diode membranes by laser lift-off

Abstract

Indium–gallium nitride (InGaN) multiple-quantum-well (MQW) light-emitting diode (LED) membranes, prefabricated on sapphire growth substrates, were created using pulsed-excimer laser processing. The thin-film InGaN MQW LED structures, grown on sapphire substrates, were first bonded onto a Si support substrate with an ethyl cyanoacrylate-based adhesive. A single 600 mJ/cm2, 38 ns KrF (248 nm) excimer laser pulse was directed through the transparent sapphire, followed by a low-temperature heat treatment to remove the substrate. Free-standing InGaN LED membranes were then fabricated by immersing the InGaN LED/adhesive/Si structure in acetone to release the device from the supporting Si substrate. The current–voltage characteristics and room-temperature emission spectrum of the LEDs before and after laser lift-off were unchanged.

Measurement of the direct energy gap of coherently strained SnxGe1−x/Ge(001) heterostructures

“…In this letter, we describe the properties of coherently strained Sn x Ge 1Ϫx alloys on Ge͑001͒ with 0.03ϽxϽ0.115 and film thickness ranging between 50 and 200 nm. Advances in substrate engineering using techniques such as wafer bonding and laser liftoff 4 may enable synthesis of dislocation-free Ge layers on Si that can serve as low cost substrates for pseudomorphic Sn x Ge 1Ϫx alloy growth.…”

Electrically Pumped III-N Microcavity Light Emitters Incorporating an Oxide Confinement Aperture

“…4c, d, the slopes of gain and FP modes jump from around 1 to 2 as the injection current reaching 5 mA (corresponds to 2.83 kA/cm 2 current density). There was no linewidth narrowing effect observed from the spectra, indicating that lasing action is still not achieved at 77 K. This superlinear emission (power factor of 2) and clear blue-shift characteristics should be related to the onset of exciton-exciton (X-X) scattering, which is usually observed in wide bandgap materials [20,21]. The wide bandwidth of X-X scattering emission can be attributed to the multi-localized-mode emission of InGaN MQW, in which indium atoms are localized and inhomogeneously distributed.…”

“…Next, a ring-shape p-contact consisting Cr/Pt/ Au alloy was deposited on the ITO layer. The sample was then bonded onto an In/Au capped Si wafer for the following laser lift-off (LLO) process [21]. After LLO, the rough u-GaN layer was removed by the polishing process.…”

Recent progress on GaN-based vertical cavity surface emitting lasers

“…The wafer was then mounted onto a silica substrate, which is nearly transparent to the wavelength of the excitation light and the VCSEL. A KrF excimer laser radiation at 248 nm was guided into the sample from back side of the sapphire to separate the sapphire from the epitaxial layers [6]. After the laser lift-off process, the sample was dipped into the H 2 SO 4 solution to remove the residual Ga on the exposed GaN buffer layers.…”