The challenge of growing GaN and its alloys, In1-xGaxN and Al1-xGaxN, is still formidable because of the lack of close
lattice match, stacking order match, and similar thermal expansion coefficient substrates, the same as GaN-based
optoelectronic materials. ZnO is the most promising optoelectronic materials in the next generation, with wide band gap
of 3.3eV and exciton binding energy of 60meV. In addition, ZnO also has been considered as a substrate for epitaxial
growth of III-Nitrides due to its close lattice and stacking order match. Our works cover the growth of n-type InGaN and
GaN epitaxial layers on lattice-matched ZnO substrates by metal-organic chemical vapor deposition (MOCVD). Since
MOCVD is the dominant growth technology for GaN-based materials and devices, there is a need to more fully explore
this technique for ZnO substrates. However, the thermal stability of the ZnO substrate, out-diffusion of Zn from the ZnO
into the GaN, and H2 back etching into the substrate can cause growth of poor quality GaN. We use a GaN buffer layer
of about 40nm to avoid Zn/O diffusion. We can investigate the Zn/O diffusion in the InGaN epilayers by means of
second ion mass spectroscopy (SIMS) depth profiles, and analyze the surface bonding of different elements by x-ray
photoelectron spectroscopy (XPS), and investigate optical and structural characterization of InGaN epilayers on ZnO
substrates by various angles spectroscopic ellipsometry (VASE). Finally, from the Raman scattering, Photoluminescence
(PL) and Photoluminescence excitation (PLE) spectra, we can determine the qualities easily and prove that we have
grown the InGaN on ZnO with a GaN buffer layer successfully.
With the power of light emitting diodes (LEDs) getting higher and higher, the issue of thermal management is getting
much more important. In this paper, we discussed a new idea to get white light without using traditional phosphor and to
enhance its extraction efficiency. Microlens is used for increasing external efficiency and shaping light pattern. The
location of micro-lens is designed carefully by considering cup reflection. We also revealed that it is important to
consider the angle of exit light from LEDs. The result shows our design is suitable for high color rendering index (CRI)
application. At the same time, the uniform white light is approached as the light has been strongly diffused. Furthermore,
we try to decrease the junction temperature as low as possible so as to increase stability and lifetime of LEDs. In order to
maintain color mixing and dissipate heat, multi-chip or four pairs of electrodes which are electroplated with copper after
bulk micromachining process within a silicon-based package are used. This novel packaging technique needs just a few
processing steps and could be mass produced for nowadays high brightness light emitting diodes (HBLEDs).
Access to the requested content is limited to institutions that have purchased or subscribe to SPIE eBooks.
You are receiving this notice because your organization may not have SPIE eBooks access.*
*Shibboleth/Open Athens users─please
sign in
to access your institution's subscriptions.
To obtain this item, you may purchase the complete book in print or electronic format on
SPIE.org.
INSTITUTIONAL Select your institution to access the SPIE Digital Library.
PERSONAL Sign in with your SPIE account to access your personal subscriptions or to use specific features such as save to my library, sign up for alerts, save searches, etc.