Laboratories

• Baskin Engineering 262: 600 sq feet class-10K cleanroom for processing of semiconductor devices (4 class 100 laminar flow exhaust fume hoods)
• Baskin Engineering 299: 400 sq feet characterization laboratory with 4’x8’ and 4’x10’ optical tables
• Baskin Engineering 148: 400 sq feet ultra optical laboratory with 4’x10’ optical tables

Major Equipment

• Riber 2300 Solid Source Molecular Beam Epitaxy machine
• JobinYvon/Horiba Raman and Luminescence Spectroscopy System
• Coherent Mira 900 Femto/Picosecond Laser
• UCSC Camera high resolution thermal imaging system(sub-micro, 0.25K resolution)
• Centre Suisse d'Electronique optical coherence tomography camera (OCT)
• Janis high temperature cryostat system CCS-450-H-204 (4~800K)
• Digital Instruments Dimension 3100 Atomic Force Microscope with scanning capacitance and NSOM capability
• 3.6 Gb/s Agilent Bit Error Rate Analyzer
• Nicolet Nexus 870 Fourier Transfer Infrared Spectrometer (12,000-600 cm-1)
• Optical Spectrum Analyzer (500-1800nm)
• Cryostat for microscopy and for optical transmission measurements (4-450K)
• RF probe station with Cascade 40GHz micropositioners
• 20GHz sampling scope with TDR, 2x 500MHz Digital Scopes
• Synthesized Swept-Signal Generator, 0.01 - 50 GHz
• Portable Spectrum Analyzer, 9 kHz to 50 GHz
• Synthesized CW Generator, 10 MHz to 20 GHz
• Vector Signal Generator 1-250MHz and Modulation Analyzer
• Noise and Interface Test Set
• Lock-in Amplifier (DSP 100KHz and 200MHz, Analog 120KHz)
• FFT Spectrum Analyzer (120KHz)
• Pulse generators (3ns rise time, 20V pulse module)
• Turbo pumping station
• West Bond Wire Bonding Machine
• FiberAlign high precision computer-controlled XYZ translation stage (6"x2"x1" travel, 25nm resolution)
• High-performance multimeters, nanovoltmeters, sub-femtoamp source meter, and 30MHz function generators
• BeamPROP photonic device simulation software (Beam Propagation Method)
• ANSYS Finite Element Analysis Software
• L-Edit mask layout software

Molecular Beam Epitaxy System

Class 10,000 cleanroom designed for semiconductor material growth and processing

• 4 class-100 laminar-flow exhaust fume-hoods
• Particulate hood; Acid hood; 2 chemical processing hoods
• Riber 2300 solid-source Molecular Beam Epitaxy (MBE)
• Rough (10-3 torr) pumping system
• Pfeiffer XtraDry piston pump; Three-stage cryo-adsorption pumping
• 3 UHV chambers:
• Introduction Chamber
• Load-lock introduction
• High-capacity CTI-Cryogenics Cryo-Torr 8 cryopump
• Analysis Chamber
• Riber ion pump
• Deposition Chamber
• Material sources:  gallium, arsenic, indium, aluminum, silicon, and beryllium; 500cc valved arsenic cracker cell
• High-capacity CTI-Cryogenics Cryo-Torr 8 cryopump
• High-capacity Riber ion pump
• Closed-loop liquid nitrogen delivery system
• Reflection high-energy electron-diffraction (RHEED)
• Mass spectrometer (RGA); Optical Pyrometer
• Computer-automated growth and monitoring

The MBE Laboratory was set up thanks to a gift from Prof. Amnon Yariv at Caltech.

Alireza Ghaffari is the engineer who transfered the machine from Caltech to UCSC and installed it at Baskin Engineering Room BE240.

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High Temperature Cryostat System

Model CCS-450-H-204 from Janis Research Company Inc.

The Janis cryostat, model CCS-450H-204, configured with the closed cycle refrigerator (CCR) system, provides a wide temperature range from 4K – 800K.  The CCR system requires no liquid helium or liquid nitrogen as a source of cooling. Instead a closed loop of helium gas is compressed and expanded, based on the Grofford-McMahon (G-M) thermodynamic cycle.  During the expansion phase of each cycle, heat is removed from the cold finger where the sample is mounted. A heater and thermometer are installed on the cold finger and are used to precisely control the sample temperature. The high temperature stage heating is provided by a 50ohm resistance. The precise temperature control is managed by Lakeshore Temperature Controller Model 331.

The system could be used for many materials research, superconductivity, cryopumps, shield cooling etc. We have been using the system to characterize the Seebeck coefficient in the range of 4K-800K.   The CCR system is easy to use for full automated measurements without the hassle of dealing with liquid gas.

Raman and Luminescence Spectroscope System

JobinYvon/Horiba Raman and Luminescence Spectroscopy System

Raman and Luminescence spectroscopy are useful techniques for the characterization of semiconductors. The Raman signal is sensitive to internal as well as external perturbations of lattice vibrations. This may affect the position, line width, line shape and intensity of the signal.  Raman spectra can provide information about different material properties related to these perturbations. The luminescence spectrum provides information about emission wavelength, essential for optoelectronic devices applications, alloy composition, temperature, stress and quantum yield.

Thermal Imaging Camera System

Micro-scale thermal imaging is a useful technique for the study of thermal transport, and device characterization and optimization.  Common techniques for high resolution thermal imaging include infrared (IR) blackbody imaging, scanning thermal microscopy (50nm thermocouple on an atomic force microscope (AFM) tip), or liquid crystal thermography (LCT), all of which require expensive equipment, and non-trivial data analysis.  Alternatively, thermoreflectance thermal imaging is method which offers non-contact, good resolution, and a relatively simple experimental setup.   

Thermoreflectance thermal measurements rely upon the weak (1/R DR/DT – 10-5) temperature dependence of the reflection coefficient of a material.  Because of the weak dependence, generally a lock-in technique is required to obtain reasonable signal to noise (1 micron, 0.1K) for a single point on the sample.  Scanning the sample leads to thermal images but only after the many hours required to scan the probe across the sample surface.  In order to obtain thermal images in reasonable time, a thermoreflectance camera, shown in figure 1, has been built which performs 16x16 ‘lock in’ operations in parallel.  This leads to a factor of 256 speed-up when scanning.  A typical 80x80 pixel thermal image now can be realized in minutes rather then several hours.

Because of the stringent requirements (Khz frame rate, 120dB dynamic range) of high resolution thermoreflecance imaging, a typical off the shelf CCD camera could not be utilized in our design.  Based on the 16x16 Hamamatsu photodiode array, each pixel of the camera has a dedicated circuit ; AC coupled gain, and a 24-bit synchronous digitization.  The analog bandwidth of the sensor is 16Khz, and the maximum sampling rate of the A/D converters is 40Khz.  Additionally the system is configured with 64Mb of dedicated RAM so that several seconds of continuous data can be acquired independent of the computer processing time.

Femto/Picosecond Laser

Installed in the lab in September was the Coherent Mira 900.  The Mira 900 is a Titanium Sapphire tunable femtosecond laser pumped by the Verdi V-8, 8 Watt pump.  The pulsed output has an average power of over 1 Watt.  A figure of the Mira, with a block diagram of the main functioning components is shown in figure 1.  The Mira uses a passive modelocking scheme; a saturable absorber, and a simple slit to reject continuous wave(CW) operation, and amplify short pulses.  Additionally, the Mirra can be configured for femtosecond, or picosecond pulsed operation.

The Mira 900 will be used for various projects, with an emphasis on imaging.  Experiments are picosecond acoustics, ballistic imaging through turbid media, optical coherence tomography (OCT), and high resolution interferometry.            

Optical Coherence Tomography (OCT) Camera

Designed, and under development, by the Centre Suisse d'Electronique et de Microtechnique (CSEM) is a camera developed specifically for use in an OCT experiement.  The camera continuously demodulates the phase envelop that is acquired during an OCT experiment.  Typically used as illumination, a super luminescent diode(SLED) is preferred because of the high optical power and low coherence length.  Figure 1 shows the CSEM camera and the SLED.

Atomic Force Microscope

The Atomic Force Microscope is used to measure surface characteristics for semiconductor wafers, lithography masks, magnetic media, CDs/DVDs, biomaterials,
optics, and other samples up to 200 mm in diameter. Its laser spot alignment system and
the ability to change scanning techniques without tools guarantee flexibility, ease of use,
and high product throughput.

The versatility of the Atomic Force Microscope is extended to integrated circuits and devices applications with the addition of SCM and NSOM capabilities. Using the AFM as the base unit, allows simultaneous topology and capacitance measurements.

SCM enables AFM researchers to measure small capacitance variations on
semiconductor samples with a high spatial resolution (< 5 nm). A user applies a selectable AC and DC bias between the sample and the conductive tip, with the tip being on virtual ground.  When scanning in contact mode, the tip and the sample form a small metal-insulator-semiconductor (MIS) capacitor. The capacitance value is monitored by a high-frequency resonant circuit. In this way, one can obtain an image of the sample’s topography and capacitance variation simultaneously, enabling the direct correlation of a sample location with its electrical properties. An important application of SCM is to measure the two-dimensional distribution of electrical carriers inside semiconductor devices. NSOM enables various optical measurements, Transmission, Reflection, Collection-Mode, Polarization, Fluorescence, and Spectroscopy with sub-wavelength resolution.

Thermostat for High Temperature Transient Characterization of Thermoelectric Materials

Accurate high temperature characterization of thin film thermoelectrics is an important step in the optimization of the material. †There is little published work regarding the measurement of thin film thermoelectric properties at high temperatures.† We have designed and fabricated a vacuum-insulated thermostat to measure thin film device and material properties from room temperature to 850 K.† The unit is capable of direct device ZT measurement as well as measurement of in-plane Seebeck coefficient and electrical conductivity as well as cross-plane thermal conductivity.† Direct ZT measurement is accomplished using the transient Harman technique with Seebeck voltage transient resolution to 200 ns with 63 dB of dynamic range.†† In-plane Seebeck coefficient measurement utilizes a differential technique in which a temperature gradient is imposed across a sample while monitoring the generated Seebeck voltage and the temperature at the precise points of voltage measurement.† In-plane electrical conductivity is measured by the van der Pauw method.† Cross-plane thermal conductivity can be measured by the 3ω technique.† Additional measurement capabilities can be easily implemented in the thermostat.

Near-infrared (NIR) Thermoreflectance

Longer wavelength thermoreflectance can be useful due to the ability to image through semiconductor material using illumination wavelengths whose energies are below the bandgap of the material.† Many state-of-the-art CMOS integrated circuits are flip-chip bonded to their package leads, prohibiting visible access to the device contacts.† In this case, thermoreflectance can be applied at wavelengths whose energies are below the bandgap of the device substrate to image the temperature distribution on the contacts through the backside of the device.† Using incoherent illumination in conjunction with an InGaAs camera, the temperature profile inside a micrometer-scale thermoelectric module is measured through silicon substrate using near-infrared thermoreflectance.

Mid-infrared Thermal Imaging Camera

The FLIR ThermaCAM SC6000 MWIR is a high speed, high resolution, science-grade infrared camera with Gigabit Ethernet, Camera Link and USB interfaces for maximum flexibility and performance. It has cryogenically cooled InSb focal plane array (640x512 pixels). Nominal temperature sensitivity is 25mK for ìblack bodyî objects.

OLYMPUS FluoView FV1000-Confocal Microscope

††††††††††† Olympus Fluoview FV1000 Microscopic system is a state-of-the-art imaging system designed for high-resolution, confocal observation of both fixed and living cells. The FV1000 offers advances in confocal system performance while providing the speed and sensitivity required for live cell imaging with minimal risk of damage to living specimens.

The FV1000 is fully motorized and configured upon the Olympus BX2 series microscopes. The fully automated Olympus microscope platforms can be interactively controlled through the FluoView software, with internal stepper motor Z-resolution of 0.01 micron. The system is designed for easy expandability, with an open configuration that facilitates attachment of imaging devices to the various imaging ports, such as those provided for auxiliary CCD cameras. XY scanning is performed with a pair of galvanometric mirrors, yielding a wide scanning range to a field number of 18. Optical zoom (up to 50x) is available, with a maximum pixel resolution of up to 4096 x 4096. Precise control of laser intensity via an advanced laser feedback system provides stable laser excitation throughout the time course of live cell studies, a necessary feature for accurate fluorescence quantification.

Other key features of FV1000 system are:

l           Spectral system provides 2nm wavelength resolution.

l           High-speed imaging at 16 frames per second.

l           High-speed spectroscopy at 1msec per 100nm.

l           Multi-line Argon (457nm, 488nm, 514nm) laser.

l           Red and Green HeNe lasers