Material Growth Platform
Plasma-enhanced Chemical Vapor Deposition (PECVD)
The PECVD system is composed of a plasma generator and a tube furnace from Thermal Scientific, and a RV12 vacuum pump from Ewards, equipped with eight gas lines. Its working temperature can be tuned from RT to 1400K range.This equipment is mainly used to grow graphene and transition metal chalcogenides.
Tube furnace
We have seven OTF-1200X-II double temperature zone tube furnaces, in which the maximum temperature can reach 1200℃. The two temperature zones are controlled by two independent temperature control systems. Based on the PID algorithm, we can achieve 30-stage programmatic temperature control. By setting the temperature control program of the two temperature zones, a specified temperature gradient can be formed in the furnace tube. In addition, we have an OTF-1200X-III three-zone tube furnace, in which the three-stage independent temperature control can be realized, and the maximum temperature can reach 1200 ℃. Our tube furnaces can be used to grow atomically thin films or bulk single crystals by CVD or CVT methods.
Muffle furnace
We have a box furnace of model KSL-1400X-A3 with a maximum temperature of 1400 ⁰C. In the meanwhile, we have one LH30/13 muffle furnace made by Nabertherm, with 5-sided heating to ensure good temperature uniformity, and maximum temperature 1300 ℃. Our muffle furnaces can be used to grow bulk single crystal materials by flux method.
Clean Room Nanofabrication Platform
Scanning Electron Microscopes and Electron Beam Lithography System
Scanning Electron Microscopes (SEM) are used for inspecting topographies of materials with a magnification range that encompasses that of optical microscopy and extends it to the nanoscale. Electron-beam lithography (NPGS) is a method to fabricate semiconductor devices. It is the practice of scanning a focused beam of electrons to draw custom shapes on a surface covered with an electron-sensitive film called a resist. The primary advantage of electron-beam lithography is that it can draw custom patterns (direct-write) with sub-10 nm resolution.
Electron Beam Evaporation and Vapor Deposition Magnetron Sputtering
Electron beam evaporation is one of the most mature and important coating method in vacuum coating technology. Vapor Deposition Magnetron sputtering is a kind of the Physical vapor deposition (PVD) method, with the advantages of the simple equipment, easy controlling, large coating area and strong adhesion. The system integrates electron beam evaporation and magnetron sputtering together, equipped with oil pump, molecular pump and cold pump, thus the maximum vacuum degree can reach 1E-8Torr. The growth of thin films and the preparation of metal electrodes finished by this system are essential processes for the fabrication of various samples.
Atomic Layer Deposition System
Atomic layer deposition (ALD) technique can achieve atomic thickness material deposition in a ‘layer by layer’manner. On contrast to common chemical deposition, the chemical reaction of the new atomic layer is directly related to the previous layer, which results in the deposition of only a single layer of atoms in one cycle. During the deposition, the parameters such as thickness, composition and structure of the deposited material can be controlled, which guarantees the uniformity and compactness of deposited films. Currently, this system is used for growing transistor dielectric layers and memristor switching layers.
Chemical Operation Room
The chemical operation room provides a convenient and safer environment for nano-fabrication. This room is equipped with common instruments such as fume hood, spin-coater, hot plate, ultrasonic cleaner, agitator, refrigerator, etc.
Material and Device Characterization Platform
Optical Microscope
4 Nikon high-performance ECLIPSE Ci series upright microscopes are used for sample observation and processing. The high-brightness environment-friendly lighting provides sufficient light intensity for phase contrast and polarized light observation. With high-quality objectives, bright and high-contrast images can be obtained. The microscope is used in conjunction with Nikon Digital Sight series cameras to make specimen imaging easy and efficient.
Atomic Force Microscope
Bruke Multimode 8 Atomic Force Microscope with high resolution and very low noise level. With Peak and Force Tapping technology, you can get high quality images in a few minutes. Various models and accessories can help us get the surface morphology and study the physical properties of the samples.
Multi-functional Glove-Box System
Recent discoveries of various quantum materials enable fundamental experimental researches on the manipulation of the exotic degrees of freedom. However, many quantum materials are unstable in the air and sensitive to oxygen and water vapor, resulting in unwanted contamination during the nano-fabrication processes and finally reducing the device performance. So we combine four nitrogen glove-boxes, so that sample exfoliation, heterostructure assembly, spin-coating, photoresist developing, metal evaporation, wire-bonding and room temperature electronic characterization, can all be performed in an inert atmosphere.
Two-Dimensional Material Transfer set-up (Inert/atmospheric Environment)
Van der Waals interaction between two-dimensional material layers allows us to stack them on layer by layer to form artificial heterostructures without introducing defects or impurities. By tuning the interaction between organic thin films and different materials, we can accomplish the processes of peeling, laminating, twisting, folding, inverting and release of two-dimensional crystals. The transfer set-up is compatible with multiple transfer techniques and can be flexibly adjusted for different conditions. By integrating stepper motors, high-resolution control of the spatial position below 0.1μm can be achieved, avoiding the disturbance and uncertainty introduced in manual operation.
Inert Atmosphere E-beam Evaporator
Many quantum materials are extremely unstable and easily damaged by oxygen or water in the air, thereby affecting the structure of the materials and the performance of the devices. We have assembled a set of electron beam evaporator used in conjunction with a nitrogen glove box to evaporate high melting point metals such as Cr, Ti, Au, Pt, etc., so that electrodes of easily oxidized two-dimensional quantum material devices can be fabricated.
Inert Atmosphere Thermal Evaporator
Low melting point metals, such as indium have been shown the ability of greatly improving the contact between the electrodes and two-dimensional materials or some three-dimensional topological materials. We have currently purchased a set of thermal evaporator working in an inert atmosphere to fabricate indium electrodes for the high performance of electronic devices. In addition, indium can be used as the source/drain electrodes and top gate electrodes for flexible electrical devices because of its good flexibility.
Inert Atmosphere Device Testing System
A room-temperature probe station is placed in a nitrogen glove box to achieve simple electric testing directly after the device is fabricated in an inert environment with the whole fabrication process isolated from the air or water vapor. This is essential for the rapid characterization of oxidizable 2D/quantum material electronic devices.
Wire-Bonders (Inert/atmospheric Atmosphere)
Wire bonder is a machine to make interconnections between an integrated circuit (IC) or other semiconductor device and its packaging during semiconductor device fabrication. Although less common, wire bonding can be used to connect an IC to other electronics or to connect from one PCB to another. Wire bonding is generally considered the most cost-effective and flexible interconnect technology, and is used to assemble the vast majority of semiconductor packages. In our lab，we usually use wire bonding to connect the electronic devices based on two dimensional materials to chip carriers. And the chip carriers are the base of the devices measurements.
Photoelectric Test Platform
Raman spectrometer
Raman spectroscopy is independent with the frequency of incident light, and only related to the structure of the scattering samples. The spectral information reflects the differences between molecular vibrational energy levels. Different chemical bonds or groups have characteristic molecular vibration modes, which lead to the corresponding characteristic Raman spectra. Therefore, Raman spectroscopy is capable of qualitative analyzing the molecular or lattice structures.
Mid-, Far-infrared Laser
The mid-infrared lasers serve as the light sources for photoelectric devices for mid-infrared detecting. There are four bands with wavelengths centered at 4, 5, 8, and 10um in our setup.
Optic Cryostat
The cryostat system of Oxford Instruments cooled by liquid nitrogen has the minimum temperature of 77K. An optical window on the top of the instrument serves for photoelectric testing. Meanwhile, it also felicitates Raman spectroscopy, photoluminescence (PL) spectroscopy and other utilities at variable temperatures.
7T Magneto-Optical System
Oxford Instruments’SpectromagPT liquid-free helium magneto-optical system with four optical windows provides a platform of magneto-optical measurement. The system can provide a base temperature of 1.5 K and a strong in-plane magnetic field of 7 T.
Low-temperature Transport Measurement Platform
Oxford Instruments Refrigerators
Oxford Instruments Teslatron PT cryogen-free cryostat systems with superconducting magnet and variable-temperature inset (VTI) provides a measurement environment under strong magnetic field and low temperature. Currently, we have three cryostats with magnetic field as large as 14T, 12T and 8T, respectively, and temperature ranging from 1.5K to 300K. With the 3He insert and the dilution refrigerator insert, the minimum temperature can reach 250 mK and 25 mK respectively. With 3-dimensional sample rotator module, magnetic field at different angles with respect to the sample is available. This system is the fundament of the low temperature magneto-transport measurement.
Electronic Testing Equipment for Weak Signal
Various types of weak signal source-measure units (SMUs) are the fundamental to characterize the transport properties of micro-scale electronic devices. Currently, we have 9 SR560 voltage amplifiers, 6 SR570 current amplifiers, 10 SR830 lock-in amplifiers, 3 current sources (keithley 6221, Yokogawa GS200), and 8 multifunctional SMUs (keithley 2636, 2635 and 2400).
Semiconductor Measurement Platform
Cascade Summit Series Manual and Semi-Automated Probe Systems
Cascade Summit series manual and semi-automated probe systems with PureLine and AttoGuard technology allow us to access the full range of testing instruments for 200 mm and 150 mm wafers. Summit series probe systems have been used in RF/Microwave and device characterization, wafer level reliability testing, electronic testing, modeling, and yield enhancement, etc.
Array test probe station
Array test probe station is utilized to implement the operations for 1 Transistor 1 Memristor (1T1R) array such as Read, Write, Matrix Vector Multiplication(MVM), etc. YB600 probe station provides connections between on-chip memristor array and off-chip test instruments. Current off-chip test instruments include M9185A(DAC), M9101A & M9120A(Matrix Switch), M9216A(DAQ), M9111A(Source-measure Unit).
Agilent B1500A semiconductor device analyzer
Agilent B1500A semiconductor device analyzer is a multi-function parameter analysis instrument integrated several functions of measurements and analysis, providing a platform to characterize the device quickly and accurately. Its basic functions include the characterization of current-voltage (IV) and capacitance-voltage (CV), and the optimum fast pulse IV test.
Lakeshore Model CRX-6.5K Probe Station
Researches on semiconductor electronic technologies require analysis and testing of semiconductor devices at both low and high temperatures. Lakeshore variable temperature probe station, which uses liquid helium closed-loop refrigerator, can reach the temperature as low as 10K. Meanwhile, the high temperature sample holder allows a maximum temperature of 675K. This probe station also allows measurements of the performance of photo detection under illumination.