In order for solar and visible blind III-nitride based photodetectors to effectively compete with the detective
performance of PMT there is a need to develop photodetectors that take advantage of low noise avalanche gain.
Furthermore, in certain applications, it is desirable to obtain UV photon counting performance. In this paper, we
review the characteristics of III-nitride visible-blind avalanche photodetectors (APDs), and present the state-of-the-art
results on photon counting based on the Geiger mode operation of GaN APDs. The devices are fabricated on
transparent AlN templates specifically for back-illumination in order to enhance hole-initiated multiplication. The
spectral response and Geiger-mode photon counting performance are analyzed under low photon fluxes, with single
photon detection capabilities being demonstrated in smaller devices. Other major technical issues associated with the
realization of high-quality visible-blind APDs and Geiger mode APDs are also discussed in detail and solutions to the
major problems are described where available. Finally, future prospects for improving upon the performance of these
devices are outlined.
Although ZnO has recently gained much interest as an alternative to the III-Nitride material system, the development of
ZnO based optoelectonic devices is still in its infancy. Significant material breakthroughs in p-type doping of ZnO thin
films and improvements in crystal growth techniques have recently been achieved, making the development of
optoelectonic devices possible. ZnO is known to be an efficient UV-emitting material (~380 nm) at room temperature,
optical UV lasing of ZnO has been achieved, and both homojunction and hybrid heterojunction LEDs have been
demonstrated.
In this paper, processing techniques are explored towards the achievement of a homo-junction ZnO LED. First, a
survey of current ZnO processing methods is presented, followed by the results of our processing research.
Specifically, we have examined etching through an n-ZnO layer to expose and make contact to a p-ZnO layer.
Wide bandgap III-Nitride semiconductors are a promising material system for the development of ultraviolet
avalanche photodiodes (APDs) that could be a viable alternative to photomultiplier tubes. In this paper, we report the
epitaxial growth and physical properties of device quality GaN layers on high quality AlN templates for the first backilluminated
GaN p-i-n APD structures on transparent sapphire substrates. The 25 μm x 25 μm device characteristics
were measured, and compared with the same devices grown on GaN templates, under low bias and linear mode
avalanche operation where they exhibited gains near 1500 after undergoing avalanche breakdown. The breakdown
electric field in GaN was determined to be 2.73 MV/cm. The hole impact ionization coefficients were shown to be
greater than those of electrons. These APDs were also successfully operated under Geiger mode.
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.