Dr Chee Hing Tan

Reader

email : c.h.tan@sheffield.ac.uk

tel: +44 (0) 114 222 5144

Qualifications

• BEng in Electronic Engineering (Communications), 1^st class, awarded in July 1998 by The University Of Sheffield.

• Awarded Peter Hopkinson Prize for the best final year dissertation in the Department of Electronic and Electrical Engineering.
• Awarded Malaysian Alumni Prize: awarded for excellent overall performance in the Engineering Faculty.

• PhD in Electronic Engineering, awarded in April 2002 by The University Of Sheffield.

Membership of Learned Societies

• Member, Institute of Electrical and Electronics Engineers (IEEE)
• Member, The International Society for Optical Engineering (SPIE)

Current Appointment

• Senior Lecturer in EEE since Jan. 2008

Previous Appointments

• Research Associate in EEE from Oct. 2001 to Oct. 2003.
• Lecturer in EEE from Oct. 2003 to present.

Teaching

Current Undergraduate Teaching

• (Sept. 2003 - present) Signals and Systems, EEE201. This is a 10 credit module providing 3 contact hours per week.

• (Sept. 2003 – present) Signal Analysis (MATLAB based) coursework, which is part of 2nd year coursework, EEE260. This coursework provides 6 contact hours per week.

• (Sept.2003 – June 2006) Supervised 3rd year Design/Research project students (3-4 students per year) and second marked project students (3-4 students per year).

Current Postgraduate Teaching

• (Sept. 2004 – present) Designed the fabrication of semiconductor device coursework, which is part of the module Semiconductor Processing and Integrated Circuit, EEE6391. This 5 credit coursework provides 12 contact hours per semester.

• (Sept. 2005 – present) Introduced a new module, Reliability and Failure, EEE6008. This was a new 10 credit module introduced in 2005 for the MSc in Electronic Engineering course, which was also introduced in 2005.

• (Sept. 2005 – present) Supervised MSc Research project students (2 per year) and second marked project students (2-3 per year).

Teaching Innovation & Development

• In EEE201, Signals and Systems, I have revised the contents of the module to introduce examples of signal analysis using MATLAB and an experimental demonstration to enhance students´ understanding. An experiment using stroboscope was used to demonstrate the effect of signal sampling at different frequencies.

• In the Signal Analysis coursework, practical examples of signal analysis such as signal recovery in radar range measurement and analysis of 1st and 2nd order circuits were introduced. A new assessment technique introduced was to use the random number generator in MATLAB to generate different parameter values in the problems presented to students. In this way each student was expected to produce different answers in their solutions. This was found to minimise plagiarism in their reports.

• EEE6008, Reliability and Failure in electronic engineering is a specialised subject. Only one suitable textbook was found from various publishers. Therefore a significant amount of the contents for this module has to be extracted from research journals such as Thin Solid Films, IEEE Transactions on Device and Materials Reliability and Microelectronics Reliability. This approach enables me to link the progress in research to this module and to provide the examples of the latest practice in the field of electronic engineering reliability.

Leadership, Management & Administration

Current Activities

• (Sept. 2005 – present) Course director for MSc in Electronic Engineering
• (Sept. 2005 – present) Admission tutor for MSc in Electronic Engineering
• (July 2005 – present) Departmental Learning and Teaching Advocate
• (Sept. 2004 – present) Departmental Ethical Reviewer

Innovations

• During my period as the course director I have managed to run the course smoothly with an average number of students of 30-40 since 2006 As the course director of the MSc in Electronic Engineering, I have been responsible for all aspects of the course including

• Planning/designing module syllabus of new modules
• Coordinating research projects for the students
• Designing personal tutorial programmes as well as organizing a plagiarism seminar to improve students’ learning experience
• Planning and conducting examiners’ board meeting
• Designing the contents of webpage for the course and poster and flyers to promote the course
• Distributing course information to potential MSc students to encourage them to come to Sheffield.
• Advising students on module choice, examination regulations and all relevant matters in the course.

• As the admission tutor, I regularly interviewed applicants to the MSc course to ensure that their English and technical abilities meet our course requirements. This is particularly important for students from China. Some of them have good technical abilities but weaker English communicating and listening skills. It is therefore crucial to interview these students prior to making decisions on their applications. To encourage students graduating from Sheffield to enrol in the MSc course, a promotional poster was designed and displayed to our undergraduates. Important information such as eligibility for discount schemes from the University was disseminated. The poster was also sent to the Sheffield University South East Asia Office to promote the course.

• As the Learning and Teaching Advocate, my main role is to facilitate teaching innovation and dissemination of best practice in teaching and learning. In addition I serve as the contact person between the university support such as learning, development and media unit, and learning and teaching support unit, and the department to promote good teaching practices. I am also engaged in discussions with advocates from other engineering departments to discuss ways of improving learning and teaching in the engineering faculties.

• As an Ethic Reviewer I am involved in review the ethical aspect of the research projects in the department.

Professional & External Development Activities

• I have refereed manuscripts for a number leading international journals such as IEEE Journal of Lightwave Technology, IEEE Transactions on Electron Devices, Applied Physics Letters, Journal of Applied Physics, Electronic Letters and Optics Express (The Optical Society of America).

• I have been invited to present my research activities in various companies such as Bookham Technology (UK), Selex Sensors and Airborne Systems (UK), Alcatel-Thales (France), Mitsubishi (Japan) and Hitachi (Japan).

• I have established strong industrial research links with Bookham Technology (UK), Centre for Integrated Photonics (UK), Rolls-Royce (UK), Thales (UK) and Selex Sensors and Airborne Systems (UK).

• I have strong research collaborations with Prof. Majeed Hayat (University of New Mexico, USA, on modelling of carrier statistics), Prof. Sanjay Krishna (University of New Mexico, USA, on infrared detectors), Prof. Joe Campbell (University of Virginia, USA, on avalanche photodiodes), Prof. Erik Janzen (Linkoping University, Sweden, on development of SiC UV detector), Prof. Gerald Buller (Heriott-Watt University, on single photon detector), Dr John Lees (Leicester University, on x-ray detector) and Prof. Alf Adams and Prof. Jeremy Allam (Surrey University, on novel material for avalanche photodiodes).

Research & Publications

Research Areas

• Mid Infrared avalanche photodiodes: I have developed InAs as a material for avalanche photodiodes (APDs) for light detection up to 3.6 µm. The InAs APDs, unlike other compound semiconductor APDs, showed negligible excess noise and hence are able to provide very large internal gain, leading to orders of magnitude improvement in sensitivity over current near to mid infrared photodiodes. The InAs APD is the subject of an ongoing patent application. I envisage that this invention will revolutionise applications such as eye-safe free space communication, active 3D ranging applications and photon counting systems. I have initiated dialogue with Selex Sensors and Airborne Systems (formerly BAE) and Thales to discuss commercial exploitation plans for InAs APDs. To date a total of £451.6k has been awarded by the Electro Magnetic Remote Sensing – Defence Technology Centre (EMRS-DTC) to develop these InAs APDs.
  
  
• High speed optoelectronics: In this are, I have set up the first frequency response characterisation up to 40 GHz in EEE, based on optical heterodyne. I have achieved photodiodes with 3 dB bandwidth of 12 GHz. New designs for avalanche photodiodes, waveguide detectors and electro-absorption modulators have been identified and will be fabricated over the next year to expand my research in high speed optoelectronics. I envisage photodiodes and modulators working beyond 40 GHz in 2 years’ time. These components will be used in 40 Gb/s optical fibre systems and radio over fibre. I am currently working very closely with Bookham Technology to develop 40 GHz photodiodes. Funding has been secured from Bookham Technology, Nuffield Foundation and the Engineering and Physical Sciences Research Council (EPSRC) to develop these high speed photodiodes.
  
  
• Low excess noise and high temperature APDs: I am currently designing and characterising InAlAs APDs to achieve low excess noise and high temperature stability. My research has shown that InAlAs produces lower excess noise and better temperature stability than InP, which is currently used in commercial APDs for optical communication systems. This work is currently funded by the Department of Trade and Industry (DTI) and part funded by the EPSRC. These InAlAs APDs are expected to be developed into high performance avalanche diodes for photon counting applications such as LIDAR and quantum cryptography in the next 2 years.
  
  
• Far infrared detectors: In this area I have set up the first infrared characterisation system upto 28µm in EEE. The main objective of the work is to develop infrared photodiodes operating at the atmospheric transmission windows 3-5µm and 8-12µm. I have characterised a series of Quantum Dot Infrared Photodiodes (QDIPs) to show that the noise of QDIPs is strongly dependent on the ratio of electron doping density and the quantum dot density. To date, we have achieve very high responsivity comparable to the best published in the world. I believe the study of noise is the main key to achieve high performance QDIPs. Strained Layer Superlattice Type II photodiodes have also been investigated as high performance infrared photodiodes. Research grants from the EMRS-DTC and from the Ministry Of Defence (MOD) have been obtained to develop these photodiodes. Together with my colleagues, we are the main research group in the UK developing these technologies and aim to be the leading group in the world in a few years time.
  
  
• Power electronics: I have recently diversified my research into power electronic devices. My strong background in semiconductor devices has provided me the knowledge to investigate and optimise the performance of semiconductor power electronics. I am currently optimising and characterising SiC diodes for power electronics. I am also modelling the performance of power electronic devices when cooled to temperature as low as 20K. This low temperature power electronic research is currently funded by the DTI with industrial support from Rolls-Royce (UK).
  

Recent Research Advances

InAs with electron only multiplication

Over the last few years we have been developing InAs avalanche photodiodes (APDs) and demonstrated avalanche gain with negligible excess noise. For the gain range measured under pure electron injection the excess noise factor is always below 2, which is lower than Si APDs and comparable to high performance CdHgTe APDs. The unique avalanche properties in InAs can be exploited for extremely high performance active range finding and a number of gas sensing application in the wavelengths range of 1 to 3µm. Since the multiplication process is only dependent on electron impact ionisation, the multiplication process will terminate by two carrier transit time. This could be exploited for high bit rate transmission since the intersymbol interference will be reduced significantly compare to conventional InGaAs/InP APDs for optical communications. Furthermore a choice of free space transmission either at 1.55µm or longer wavelengths is available with InAs APDs. Typical avalanche gain and excess noise factors measured are shown in Figure 1.

A versatile novel algorithmic infrared spectrometer

We have been developing quantum dot infrared photodiodes (QDIPs) that exhibit a large variation in the spectral response as a function of applied bias. Using an algorithm we have been able to demonstrate a novel algorithmic infrared spectrometer. This technique when fully developed will provide a compact, portable spectrometer since neither scanning optics nor filters is required. Our QDIPs have been designed to achieve low dark current and hence high detectivity ~ 10¹⁰cmHz^1/2/W. An example of our QDIP spectral response is shown in Figure 2. The voltage tenability enables our QDIPs to successfully capture the absorption feature of a polyethelyne sheet, even though the spectral responses have typical full width half maximum values > 0.5µm.

Research Grants & Contracts

My total research income from Oct 2003 to present is ~£2.42 million (£1.01 million as Principle Investigator and £1.41 million as Co-Investigator). The breakdown of the income is summarized in 5.2.1 and 5.2.2. These projects were awarded by Engineering and Physical Sciences Research Council (EPSRC), Department of Trade and Industry (DTI), by Electro Magnetic Remote Sensing- Defense Technology Centre (EMRS-DTC), Nuffield Foundation, Bookham Technology, Ministry of Defence-Competition of Ideas (MOD-COIs), Science and Technology Facilities Council (STFC), Technology Strategy Board and European Framework Progamme 7 (EU FP 7).

Principle Investigator

• EMRS-DTC (£155,800): Novel low voltage InAs avalanche photodiodes for affordable 2D IR photodetectors, 3^rd year funding. Duration: April 2008-March 2009.
• MOD COIs (£106,516): 2 Band Quantum Dot Infrared Photodiodes for Mid- and Long-Wave Infrared Scene Sensing. Duration: Nov. 2007 – Oct. 2008.
• DTI (£206,213): Superconducting Systems. Partners in this project are Rolls-Royce, University. Duration May 2007 – April 2010.
• EMRS-DTC (£81,800): Novel low voltage InAs avalanche photodiodes for affordable 2D IR photodetectors, 2^nd year funding. Duration: April 2007-March 2008.
• EMRS-DTC (£50,000): Multicolour InAs photodiodes for IR 2D array. Duration: Jan 2007-March 2007.
• EMRS-DTC (£51,000): Novel low voltage InAs avalanche photodiodes for affordable 2D IR photodetectors, optmisation of fabrication procedures. Duration: Oct. 2006-March 2007.
• EPSRC (£170,000): Novel InGaAs/InAlAs travelling-wave avalanche photodiode for ultra high speed photonic applications. Duration: Jul 2006-June 2009.
• EMRS-DTC (£98,000): Novel low voltage InAs avalanche photodiodes for affordable 2D IR photodetectors. Duration: April 2006-March 2007.
• EMRS-DTC (£15,000): InAs avalanche photodiode for IR 2D array. Duration: Sept 2005-Dec 2006.
• Nuffield Foundation (£5,000): Travelling-wave avalanche photodiode for ultra high speed applications. Duration: March 2005-May 2007.
• Sheffield University studentship (~£45,000) to investigate GaAs based IR photodetector. Duration: Oct. 2004-Sept. 2007.
• Case studentship from Bookham (£15,750) from Oct. 2004-Sept. 2007.

Co-Investigator

• EU FP7 ICT (€433,543): Materials for avalanche receiver for ultimate sensitivity. Duration: May 2008-April 2011.
• EMRS-DTC (£115,000): Infrared photodiodes based on Type II Superlattices, 2^nd year funding. Duration: April 2008-March 2009.
• Technology Strategy Board (£184.553): Extended Temperature Optoelectronics II. Duration: Oct. 2008-July 2011.
• MOD COIs (£95,912): Detectors for UV non line-of-sight communication. Duration: Nov. 2007 – Oct. 2008.
• STFC (£88,270): Avalanche photodiode array for eye-safe imaging. Duration: Nov. 2007 – Oct.2009.
• EPSRC (£178,686): New high-performance avalanche photodiodes based on unique properties of dilute nitrides. Duration: Oct 2007 – Sept 2009.
• EMRS-DTC (£128,000): Infrared photodiodes based on Type II Superlattices. Duration: April 2007-March 2008.
• DTI (£120,000): Extended Temperature Optoelectronics. I am the project manager as well as the steering committee member for Sheffield. Partners in this project are Centre of Integrated Photonics, Bookham Technology, Epichem, Loughborough Surface Science and University of Surrey. Duration: Sept. 2005-April 2008.
• EMRS-DTC project (£162,000): Quantum Dot Infrared Photodiode. Duration: Apr. 2005- March 2007.

Research Supervision

2 post doctoral research associates

6 PhD students, 3 students expected to complete within the next 6-9 months and 2 new students expected to start in Sept. 2008

1 student funded by an EPSRC DTA and CASE studentship, 1 student funded by Sheffield University studentship, 1 student funded by an EPSRC studentship and fee waiver, 2 students funded by research grants.

Publications

A list of publications is available in the links to the right.

International Refereed Journals

• 27 in print
  
• 2 in press

Refereed International Conference Papers – 19

Other Conference Papers - 13