Using 2.3T electromagnet, it possible to carry out Hall effect measurements at temperature range from 10-320K. The system is used to determine carrier concentration and mobility as a function of temperature.
I-V (a.c. and d.c)
We have several oscilloscopes and high voltage sources for a.c. I-V measurements, as well as dc power supplies, electrometers for d.c electrical characterization.
Spectral Photoconductivity
PC spectrum gives information about bandgap energy and the presence of defect/trap levels.
In the PC set-up, sample is placed onto cold finger of a closed-cycle refrigerator, and the temperature is kept at any desired value to within 0.1 K, in the range of 30-300K. The light from a quartz halogen lamp is focused on a 0.5 m grating monochromator, through a variable speed optical chopper, and light intensity controlled by a constant current source. The modulated photocurrent at the frequency of the chopped light, the a.c excitation intensity are simultaneously measured as a function of the photon energy..
Temperature range : 30 – 300K (with close cycle refrigerator) | 2 – 300K (with LHe bath cryostat)
Wavelength range : 200nm – 10 um
Acoustofluidic
Acoustofluidic systems utilize RF (Radio Frequency) signals to control and manipulate the movement of particles at the microscale. These systems allow precise manipulation of fluids and particles at the microscale through small-scale channels on microchips. RF signals are applied via electrodes placed on piezoelectric materials, generating acoustic waves to manipulate or mobilize particles within the fluid. These waves guide the flow of liquids through microchannels and can transport, mix, or separate micro-sized particles. Combined with the rapid response times and high precision of microfluidic systems, RF signals enable the execution of complex processes at the microscale in various fields such as biotechnology, medicine, chemical analysis, and many others.
Photoluminescence
Temperature range : 1.6 K– 300K
This method is used to determine bandgap energy of the semiconductors. At the system, high power (up to 5W) Argon-ion laser is utilized as excitation source.
Temperature range : 1.6 K– 300K
Wavelength range : 200nm – 10 um.
Reflectance | Photo- and Electromodulated Reflectance
Modulation spectroscop techniques such as photo, electroreflectance and contacless electroreflectance gives very useful information about energies of bandgap and subband transitions even at rooom temperature.
Photomodulated reflectance measurement is based on modulation spectroscopy. The PR spectrum shows derivative characteristics. This method gives very useful information about band gap transition energies even at room temperature owing to sharp derivative spectrum at transition energies. In PR measurements, a halogen lamp and a single grating monochromator is used in order to illuminate a spot on the sample. Meanwhile sample is modulated by a chopped laser. The modulated reflectance is measured with a diode. The output of the detector contains both dc R and ac R signals. These components are monitored by using digital voltmeter for dc R and lock-in amplifier for ac R. Photomodulated reflectance signal equals to dR/R. This system is computer controlled like PC,PV and R. The outputs of lock-in amplifiers and digital voltmeter are connected to the computer. Obtained data is plotted versus wavelength.
Spectral Photovoltage
In-plane PV spectrum gives information about the defect levels in investigated structures. On the other hand PV enables to measure open circuit voltage under illuminations.
n the PV set-up, sample is placed onto cold finger of a closed-cycle refrigerator, and the temperature is kept at any desired value to within 0.1 K, in the range of 30-300K. The light from a quartz halogen lamp is focused on a 0.5 m grating monochromator. Open circuit PV signal and excitation intensity measured by a conventional lock-in amplifier.
Temperature range : 30 – 300K (with close cycle refrigerataor) | 2 – 300K (with LHe bath cryostat).
Wavelength range : 200nm – 10 um
10, 100 and 1000 Classes Cleanrooms in a 100 m2 Area
2-twin 2 m long wet benches located in 30m2 yellow room (Class 100) with hot plates, spin coaters, ultrasonic cleaners. The class in the wet benches is 10.
Photolitography componenets, Mask Aligner, Profilometer, are installed in the yellow room
Class 1000 room includes drys etching instruments (Focused Ion Beam/E-beam lithography), SEM with EDS detector, Wire Bonder, Thermal Evaporator.
Focused Ion Beam | Electron Beam (Versa 3D FIB-SEM/EDS Dual Beam and Raith Electron Beam)
The high-current Focused Ion Beam (FIB) enables fast material removal and low voltage clean-up for low-damage surface finishing in high vacuum mode. Gas chemistries are available for depositing materials or enhancing FIB milling rate or selectivity. Nonconductive samples are easily milled with the automated Drift Suppression milling mode. With Versa 3D the choice is yours to optimize the system for conductive samples in high vacuum; non-conductive samples with low vacuum.
Typical Applications of Dual Beam Microscopes;
Site Specific Cross Section Analyses: This technique is typically suited for volumes up to 100 × 100 µm cross section areas. .
Micro and Nanostructuring: dual beam microscopes (DBM) are often equipped with Gas Injection Systems (GIS) to introduce different functional precursors which allows then for the fabrication of (functional) micro- and nanostructures. Basically, one can divide this maskless direct write methods in two main classes.
Versa 3D FIB-SEM (Dual-Beam™) system is also equipped with Raith E-Beam Lithography for making complex patterns and structures at nano scale.
Versa 3D FIB-SEM (Dual-Beam™) system is also equipped with Raith E-Beam Lithography for making complex patterns and structures at nano scale.
Twin Chamber Thermal Evaporator (VAKSIS)
The evaporator has twin chamber for enabling metallization process seperately for n- and p-tyep semicondcutors. Every chamber has 3 electrodes.
Magnetron Sputtering System
Magnetron Sputtering is a physical vapor deposition (PVD) method used in various fields such as semiconductor devices, optical coatings, decorative coatings, and hard coatings. This technique involves ejecting atoms from the surface of a target material in a vacuum environment using plasma, which then deposit onto a substrate. Magnetron Sputtering produces high-purity and homogeneous coatings with nanometer-level thickness control. It allows for the coating of both conductive and insulating materials, offering a wide range of applications. The device properties are ;
A gas flow and control unit with three mass flow controllers for Ar, N2, and O2 gases,
A sample holder that rotates on the Y-axis and moves on the Z-axis, with an adjustable rotation speed of 3-30 rpm, heats up to 500℃, and is suitable for samples of 4” or smaller,
A PID control unit for sample temperature with a temperature uniformity of 50-500℃ ±1℃,
One 2” DC and two 2” RF "Flex Head" magnetron sputtering sources,
A "cold finger" setup that can be filled with LN2 for high-level vacuum cleanliness.
Wire Bonder
Wire bonder is a ball bonder with 0.19, 0.25 and 0.5 micron gold wires.
Wet Benches
Twin wetbenches, 2 meter long each, includes ultrasonic cleaner, spin coater, hot plates.
AFM (Park System)
AFM has Non-Contact ve Tapping Mod Atomic Force
Lateral Force ve Force Distance Spectroscopy
Electric Force Microscopy
Nanolithography
Nanoindentation
Scanning Tunneling
Microscopy ve Phase Imaging modes
Magnetotransport Measurements
Magnetotransport measurements are carried out using 18/20T and 7T superconductive magnets at temperature range between 10mK-300K.
Magnetotransport measurements are useful to obtain information about electronic transport properties, power loss mechanisms of hot electrons, investigate the scattering mechanisms of carriers, determine the carrier density, effective mass, transport mobility, quantum mobility and Fermi energy of two-dimensional (2D) electrons in each subband, and subband separation in heterojunctions..
Cryogenic Generator Plants
LN2 generator plant has a production capacity of 40liter/day.
LHe Recovery / Helium Liquefier System,
LHe Recovery system is used to collect the helium gas from the superconductrive magnet systems. The components of the system are a 21m3 helium bollon and helium compressor, gas bottles.
Helium Liquefier system produces 18liter helium a day.
Modular Micro Spectroscopy
Modular Micro Spectroscopy is a home-build setup equipped with a spectrometer (Shamrock 500i, Andor) and a thermoelectric cooled Si CCD (Newton BEX2-DD, Andor) and PylonIR InGaAs CCD. The spectral range of the system is 200 nm to 1750 nm. It is equipped with a 532 nm CW laser (Gem532, Novanta Photonics) as an excitation laser with 0.7 beam diameter (with 100X, NIR, 0.7 NA objective) and a XYZ piezo sample stage (20 nm step resolution). With 1800 g/mm grating the spectral resolution is 0.6 cm-1, and Raman wave numbers range is about 90 - 10000 cm -1
In this experimental setup many different spectroscopic techniques can be employed light to interact with matter and thus probe certain features of a sample to learn about its structures and optical properties.
Micro-Raman spectroscopy
Micro-Photolominecance spectroscopy
Fluorescence spectroscopy
Reflectance and Transmittance spectroscopy
Spectral mapping options with high spatial resolution
Viscoelastic Transfer System
Viscoelastic transfer using polydimethylsiloxane (PDMS) stamps is a widely used technique for the precise placement of 2D materials and the fabrication of van der Waals heterostructures. The PDMS-based transfer allows fast and convenient, enabling the deterministic transfer of 2D materials via micro-manipulator on virtually any substrate without requiring wet chemistry. This technique is best suited for fabricating individual monolayers and integrating them into existing structures, such as pre-patterned contacts and photonic and plasmonic devices.
Our system features a custom-built microscope equipped with a digital camera, a sample holder with a PID-controlled heater, and piezo XYZ stage nano-manipulators for precise remote control, enabling the transfer of 2D materials onto different substrates and materials.
