Facilities for Studying Design & Growth
- In-situ TEM (MERLION System)
- Metal Organic Chemical Vapour Deposition (MOCVD - Nitrides)
Facilities for Micro- and Nano-Fabrication
- Inductive-Coupled Plasma Etching System
- E-beam Lithography
- Class 100 (ISO Class 5) Cleanroom -
Facilities for Materials Characterisation - Mechanical Properties
- Nano-indenter with Atomic Force Microscope
- Ultra-high Precision Control Micro-force Tester
Facilities for Materials Characterisation - Microscopy & Microstructural Analysis
- Home-built Scanning Microprobes
- Scanning Electron Microscope (SEM)
- Transmission Electron Microscope (TEM)
- Ballistic Electron Emission Microscopy (BEEM)
- Monochromated scanning transmission electron microscopy (M-STEM)
Facilities for Materials Characterisation - Optical Characterisation
- Micro-Raman Systems
- Scanning Near Field Optical Microscopy
Facilities for Materials Characterisation - Spectroscopy & Chemical Analysis
- Time-of-Flight Secondary Ion Mass Spectroscopy (ToF-SIMS)
- Nuclear Magnetic Resonance (NMR)
- X-Ray Photoelectron Spectroscopy (XPS)
- High-resolution X-Ray Diffraction (HRXRD)
Facilities for Studying Design & Growth
In-situ TEM (MERLION System)
The system is a modified electron microscope for real-time in-situ observations at the nanoscale. It comprises a 200kV Transmission Electron Microscope (TEM) equipped with in-situ e-beam evaporation, gas injection and energy filtered TEM (EFTEM). The system permits real-time imaging of design & growth and reaction phenomena on a sub-nanometre length scale. The ability to directly observe design & growth and reaction phenomena in-situ enables the mechanisms of microstructural evolution to be elucidated more efficiently than conventional post-mortem examination. Using this system, IMRE is able to study nucleation, growth and coalescence/reaction pathways through diffraction patterns, bright-field, dark field, imaging at near atomic resolution. The system is also able to use the energy filter (EF) to conduct EF-TEM and electron energy loss spectroscopy analysis at nanometer resolution.
Metal Organic Chemical Vapour Deposition (MOCVD - Nitrides)
A Veeco D180 low pressure MOCVD system is used for the growth of III-Nitrides for the fabrication of ultra-violet, blue, green and white LEDs and semiconductor lasers emitting in the UV, violet, blue and green wavelengths. The system is capable of growing six 2-inch wafers with substrate rotation. The substrates used are sapphire, silicon and free standing GaN. Materials studies include growth of quantum dots, piezoelectric effects on the optical emission in quantum wells and microcavities. The system is equipped with an Epimetric monitor for in-situ reflectivity measurement. The n-type and p-type dopants are Si and Mg/Zn respectively.
Facilities for Micro- and Nano-Fabrication
Inductive-Coupled Plasma Etching System
The inductively coupled plasma (ICP) system is typified by a high density plasma discharge. The system is used to etch III-V semiconductor materials such as GaAs /GaN and to etch silicon materials in submicron depth during various device fabrication steps. The system consists of two chambers, namely, process and load lock, capable of evacuating to base pressures of 10-6 Torr. Chlorine/Fluorine based gases are introduced to etch the materials in a plasma, generated by an RF power operating at 13.56 MHz. An additional 2 MHz ICP RF source is superimposed to create high-density plasma with minimal damage on the sample. Anisotropic etch profiles and variation in etch rates can be achieved by optimizing various process parameters.
The electron beam direct-write lithography system is used to define fine patterns for research and industry application. The system is capable of writing sub-50 nm patterns with an acceleration voltage of 100kV. Various processes based on different kind of photoresists have been developed on different substrates such as Si, glass, III-V. It is capable of processing irregular shape sample to regular shape up to 200 mm diameter wafer.
Class 100 (ISO Class 5) Cleanroom
The Cleanroom facility in IMRE has capabilities in micro and nanofabrication for Si and non-silicon materials, with tools like photolithography, laser direct writing system, dry etching, thin film deposition (sputtering system, e-beam evaporator, PECVD & MOCVD), annealing, electroplating and nanoimprinting.
Facilities for Materials Characterisation
Nano-indenter with Atomic Force Microscope
The Nano-indentation/AFM system is a unique instrument for characterising the elastic, plastic, stress-strain, hardness, creep, fracture, residual stresses and other mechanical properties of coatings, thin films, interface, bulk materials and the near surface region of materials. The force resolution is 0.75 mN; displacement resolution is 0.05 nm.
Ultra-high Precision Control Micro-force Tester
The MicroTest systems are designed to meet the requirements of a broad variety of sub-miniature testing applications. It has high precision position control, displacement measurement resolution better than 50nm, high stiffness load frame, testing in environmental chamber, light weight pneumatic micro tensile grips, micro bend fixture, micro indentation tools, die shear fixture, ball shear fixture, variable angle micro peel fixture, constant 90 degree angle peel fixture, XY-Theta positioning stage, vacuum stage, vision system using microscope of video camera.
Microscopy & Microstructural Analysis
Home-built Scanning Microprobes
A range of both home built and commercial scanning probe microscopes is available in the Micro & Nano Systems Cluster. These include two molecular imaging systems for fine scale imaging, a Topometrix instrument for scanning large wafer size samples, a Digital Instruments STM electrochemical STM, an Omicron UHV AFM and a Nanofactory STM/TEM mount for insertion within a TEM. Homebuilt equipment includes a liquid AFM, a BEEM STM and a future cryogenic STM/AFM.
Scanning Electron Microscope (SEM)
A scanning electron microscope forms an image of the surface of materials by scanning a fine electron beam. Both secondary and backscattered electrons can be collected giving information about the surface topography and atomic weight of the sample. Our field emission SEM has a resolution of 1 nm at 15 kV and above accelerating voltages and 2.5 nm at 1 kV and our tungsten filament SEM has a resolution of 3.5 nm. Both SEMs have an X-ray spectrometer for elemental identification.
Transmission Electron Microscope (TEM)
A transmission electron microscope can be used to image thin (<100 nm) sections of materials at high resolution. Our 300 kV field-emission microscope is a high resolution instrument capable of resolving atom columns separated by only 0.17 nm. It can also be used to determine crystal structure using bright-field images, dark-field images and diffraction patterns. An X-ray spectrometer allows chemical composition to be determined at nanometre resolution.
Ballistic Electron Emission Microscopy (BEEM)
The ballistic electron emission microscopy (BEEM) technique is a variant of scanning tunnelling microscopy (STM). BEEM is used to determine, with nanometer resolution, the electronic properties of buried metal-semiconductor interfaces. It can work in spectroscopy mode or as an interface imaging tool. The technique can be applied to a wide variety of organic and inorganic semiconductors covered with metals. IMRE is the only institute in Singapore with dedicated facilities and extensive knowledge related to BEEM research.
Monochromated scanning transmission electron microscopy (M-STEM)
M-STEM provides sub-Angstrom resolution images and a wide range of analyses on the physical properties and chemical compositions of materials.
Contact:Dr Lin Ming
The JYT64000 system equipped with both micro- and macro-chamber is used for Raman scattering measurements. The system is capable of measuring spectra from both solid and liquid samples. Using this system, it is possible to investigate crystal structure, orientation, composition and stress in semiconductors. In-situ temperature dependent measurements in polymers and biomaterials can also be carried out. Simultaneous polarised uv-visible Raman excitation can be performed using a Spectra Physics Ar+ laser (Excitation wavelengths: 514.5 - 457.9 nm, 351.4 nm, 363.8 nm). Room temperature micro-Raman spectra can be recorded from samples with a spatial resolution of 1.0 mm. The spectral resolution of the set up is 0.2 cm-1. Temperature dependent measurements (77 - 500 K) with a lateral resolution of 2.0 mm can be explored using the OXFORD Microstat microscope cryostat.
Scanning Near Field Optical Microscopy
The scanning near-field optical microscope has been implemented for ultraviolet visible-near infrared imaging in the illumination mode. This technique is useful to study optical properties from materials with sub-wavelength spatial resolution and with AFM capability. The optical properties can be easily correlated to topographic information. The system is equipped with He-Cd (325 nm) and Ar+ (514.5 - 457.9 nm) laser sources. Al/Cr/Au coated optical fibre probe with aperture 50 nm serves as a nanosource through which photoluminescence can be excited from semiconductors and light emitting polymers. The microscope is equipped with various detectors (PMT, APD and InGaAs photodiode) to perform broadband photoluminescence intensity mapping.
Spectroscopy & Chemical Analysis
Time-of-Flight Secondary Ion Mass Spectroscopy (ToF-SIMS)
ToF-SIMS allows determination of chemical composition of materials and the distribution of chemical species through the depth of the sample. ToF-SIMS uses a pulsed primary ion beam to desorb and ionise atoms and molecules from the surface of a sample. The resulting secondary ions are accelerated into a mass spectrometer, which measures their “time-of-flight” from the sample surface to the detector to determine the mass of the ions. Because each element has its own mass, analysis of the mass spectrum allows us to determine what elements are in the sample. Depth profiles are obtained when the sample is gradually sputtered and mass spectra are measured from deeper and deeper layers.
Nuclear Magnetic Resonance (NMR)
This is an essential equipment in the study of molecular structure especially in polymer and protein structure elucidation. The NMR is equipped with both liquid and solid-state probes which enable the study of organic or inorganic materials either in liquid or solid state under a 400 MHz (9.4 Tesla of magnetic field strength) spectrometer.
X-Ray Photoelectron Spectroscopy (XPS)
The VG ESCALAB 220I-XL system is an extremely versatile XPS system. It is equipped with two types of X-ray sources: the twin-anode (Mg/Al) and the twin crystal monochromated Al source, producing spectra from areas ranging from 8 mm down to 20 mm in diameter. The use of the X-ray monochromator with small spot size allows selected area analysis. The lens and analyser combination can also be operated at maximum sensitivity. This instrument is also able to produce elemental mapping with a spatial resolution of 1 mm. Other capabilities of the system include depth profiles, line scans, angle-resolved XPS and ion scattering (1 keV He+).
High-resolution X-Ray Diffraction (HRXRD)
HRXRD provides information about crystallographic structures, textures and chemical compositions of unknown materials. Using a monochromatic beam, the internal stress can also be measured.