Research Profile - Department of Materials Science and Metallurgy ...

Colin Humphreys CBE FREng
Emeritus Goldsmiths’ Professor of Materials Science
BSc Imperial College
PhD University of Cambridge
MA University of Oxford
Hon DSc University of Leicester
+44 (0)1223 334457
colin.humphreys@msm.cam.ac.uk
www.msm.cam.ac.uk/GaN
Gallium Nitride, Electron Microscopy and Aerospace
My research is broad and covers three main areas: gallium nitride
materials and devices; advanced electron microscopy; and hightemperature
aerospace materials.
Gallium-nitride materials and devices
Gallium nitride (GaN) is probably the most important
semiconductor material since silicon. It emits brilliant light as
well as being a key material for next-generation transistors.
The Cambridge Centre for Gallium Nitride in the Department
has world-class growth and characterization facilities. On the
same site we have a six-wafer MOCVD growth system, plus
a range of world-class characterization equipment, including
advanced electron microscopy and analysis, high-resolution
X-ray diffraction, atomic-force microscopy, photoluminescence
mapping, etc. My group of about 20 works at the cutting edge of
GaN research worldwide. Our research goes from fundamental
studies through to applications in LEDs and lasers, including
next-generation solid-state lighting and UV LEDs for purifying
water in the developing world.
Advanced electron microscopy and analysis
We are developing and applying a range of advanced electron
microscopy techniques. For example, we have pioneered energyfiltered
secondary-electron imaging in scanning electron microscopy
for the mapping of dopants in silicon and other semiconductor
devices. We are applying high-resolution electron microscopy,
electron-energy-loss spectroscopy and electron holography to
gallium nitride based structures in particular. An aberration-corrected
and monochromated electron microscope will shortly be delivered,
which together with a new dual-beam focused-ion-beam instrument
will keep electron microscopy at Cambridge as a world-class centre
(see www.msm.cam.ac.uk/hrem).
High-temperature aerospace materials
The Department contains the Rolls-Royce University Technology
Partnership in Advanced Materials. We are designing and
developing higher-temperature advanced alloys that will improve
the efficiency of gas-turbine engines, resulting in reduced fuel
consumption and reduced emissions.
P Kazemian, SAM Mentink, C Rodenburg & CJ Humphreys, “High
resolution quantitative two-dimensional dopant mapping using energyfiltered
secondary electron imaging” J. Appl. Phys. 100, 054901 (2006).
MJ Galtrey, RA Oliver, MJ Kappers, CJ Humphreys, DJ Stokes, PH Clifton
& A Cerezo, “Three-dimensional atom probe studies of an In x
Ga 1–x
N/GaN
multiple quantum well structure: Assessment of possible indium clustering”
Appl. Phys. Lett. 90, 061903 (2007).
DM Graham, P Dawson, GR Chabrol, NP Hylton, D Zhu, MJ Kappers, C
McAleese & CJ Humphreys, “High photoluminescence quantum efficiency
InGaN multiple quantum well structures emitting at 380 nm” J. Appl. Phys.
101, 033516 (2007).
3-D atom-probe image of InGaN/GaN quantum wells. Each dot
represents a single atom: light blue is gallium and orange is indium
Research Profile 23