國立清華大學演講公告
物理學系
光電研究中心
前瞻物質基礎與應用科學中心
Time﹕04/12 (Thur.) 13:30-14:30
Place﹕Physics Building 208R
Speaker﹕Dr. Chee-Hing Tan
( Electronic and Electrical Engineering, The University Of Sheffield)
Title﹕Towards solid state photomultiplier (& low noise avalanche photodiodes)
Abstract﹕
Photomultiplier is well known for providing high amplification without incurring excessive
amplification noise, although the quantum efficiency is governed by the efficiency of the photocathode
used. Solid state avalanche photodiodes (APDs) on the other hand offer significantly higher quantum
efficiency and high amplification. The amplification generates excess noise and research in APDs has
been focused on making semiconductor APDs performing as solid state photomultiplier by removing the
excess noise.
In this talk, development of InAs APDs, towards a true solid state photomultiplier, will be presented.
High gain with excess noise factor of ~1.5, below the conventional noise theory was demonstrated
confirming the unique “electron only ionization behaviour in InAs”. Effort in reducing the surface
leakage current and increasing the avalanche gain generated at a given voltage will be discussed.
Gain-bandwidth product up to 580GHz was also obtained as expected for electron only ionization APDs.
An alternative approach in reducing the noise using nm scale structure will also be discussed. Results
from a range of potential compound III-V semiconductors will be presented. This approach offers the
advantage of material combinations to achieve high performance room temperature APDs at infrared
wavelengths upto 2.5m.
Finally some discussion of the potential of APDs for high speed telecommunications will be provided.
Results from conventional InGaAs/InAlAs APDs fabricated into travelling wave APDs, as well as novel
APDs fabricated from InGaAsN/AlGaAs, InGaAs/AlAsSb and InAs quantum dots on Si will also be
presented.
Dr Chee-Hing Tan completed his BEng and PhD degrees in Electronic Engineering in July 1998
and Apr. 2002 respectively, at the Department of Electronic and Electrical Engineering (EEE), The
University Of Sheffield (TUOS). From Oct.2001 to Sept. 2003 he was a research associate and was
appointed to an academic position in October 2003 at EEE TUOS. He became a Senior Lecturer in
Jan 2009 from Jan 2011 he has been a Reader in Optoelectronic Sensors. Dr Tan’s specialist
research is in high performance semiconductor-based sensors, encompassing a broad
electromagnetic spectrum from X-ray to far infrared. Over the years he has developed several
numerical models for studying hot carrier transport in semiconductors, specialising in modeling the
stochastic processes of impact ionization and breakdown mechanisms, avalanche multiplication,
noise and bandwidth of APDs. The solid understanding of the physics of semiconductor devices is
complemented by a range of skills in noise and optical measurements (particularly in
semiconductors with narrow bandgaps) as well as design, fabrication and characterisation of a wide
range of semiconductor sensors including high speed (>30 GHz) optical sensors, travelling wave devices, phototransistors,
SPADs, X-ray detector and nanostructure-based, quantum dots and superlattices, IR sensors. To date his research has led to 61
highly rated international journals and >60 conference papers. He is a regular reviewers for several journals and since Dec.
2010 he is an Associate Editor for Optic Express.
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