SSLEEC is a collaborative center, which partners key industry leaders and UCSB researchers to advance solid-state lighting and energy efficient power switching using wide-bandgap semiconductors. The Center is focused on new semiconductor-based technologies for energy efficient lighting, power electronics, and bulk growth of Gallium Nitride (GaN).
MAIN RESEARCH AREAS:
High Efficiency LEDs for Lighting and Displays
Power Electronics using AlGaN/GaN (98% efficient > 2kV)
Bulk Crystal Growth
CENTER & LEADERSHIP:
The general research interests of the group are on the heteroepitaxial growth of novel materials and structures to form the basis for making new electronic, optoelectronic, magnetic and micromechanical devices. Critical to the advancement of materials and structures is the fundamental understanding of growth. A key to developing structures with novel properties is the ability to control, at the atomic level, the interface structure and chemistry.
The program has a strong emphasis on heteroepitaxial growth of dissimilar materials. These include materials with different crystal structure, bonding, electronic, optical and magnetic properties.
Palmstrøm Group — Areas of Research
At a fundamental level, our research concerns novel physical phenomena that occur when light interacts with objects of subwavelength dimensions. As engineers, we exploit these discoveries to make smaller, faster, and more efficient photonics technologies. The essential constituents of these investigations are individual subwavelength elements we refer to as “optical antennas”.
We are particularly interested in antenna-like effects arising from oriented multipolar resonances in dielectric and molecular constituents. We study how these effects lead to novel optical properties in engineered metamaterials and organic semiconductors respectively. We use engineered nanoantennas as model systems for understanding and influencing electromagnetic phenomena in atoms and molecules. Ultimately, we hope this research will lead to a future where optical properties are controlled and engineered at the atomic or molecular level.
Our research comprises investigations in the following areas:
The Bowers group develops new optoelectronic components and photonic integrated circuits (PICs) for advanced fiber optic communications networks and optical interconnects. Our focus is on integrating optimum waveguiding materials, which do not interact strongly with light, with materials better-suited for active components. Most of this research falls into one of the following two areas:
Our group also explores ways to efficiently convert heat and light into energy:
Integrated photonics greatly reduces the size, weight, and power (SWaP) while improving performance and reliability of photonic systems. The iPL pioneers integrated photonic technologies for a diverse set of applications including:
Our mission is to develop novel materials, devices and photonic integrated circuits (PICs) to enable systems that are beneficial to society.
Our group has developed expertise in a broad range of photonic technology platforms including the compound semiconductors indium phosphide (InP) and gallium arsenide (GaAs), silicon photonics (SiPh), and planar lightwave circuit (PLC) such as silica, alumina, and silicon nitride. For each application or project, we apply the most suitable technology. We also oftentimes merge more than one technology with hybrid and heterogeneous integration techniques.
RF Circuits for Reconfigurable Radios
We as a society demand wireless mobility. As more devices share the same spectrum (e.g. WiFi, Bluetooth, cellular), the result is a radio-frequency traffic jam. This congestion has spurred interest in next generation –5G – access technologies. Solutions to RF spectrum congestion require transformative approaches to radio design and spectrum access. Two potential solutions include finding new spectrum or developing cognitive radio techniques for collaborating within the existing congested spectrum. One proposal to find new spectrum is to exploit microwave and millimeter-wave frequency bands where 50 times the bandwidth is available compared to current RF bands, allowing for a substantial increase in the data rate of wireless networks.
Professor Buckwalter is investigating several solutions for future wireless networks including millimeter-wave transmitter and receiver circuitry, phased array systems for beamforming, and software defined techniques for transmitter and receiver. By using highly-scaled (nanometer) CMOS IC technologies, our group investigates new circuit and system approaches that leverage electromagnetics, analog circuitry, digital signal processing, and device physics. We seek to understand the fundamental limits of communication through the implementation of integrated circuits and systems.
To learn more Prof. Buckwalter's research, see his group website.
The Blumenthal Group’s research includes systems level photonic networks, photonic integrated circuits, and low loss waveguides.
It is widely recognized that technologies that can intelligently manipulate light (photons) is the key to addressing current and future challenges in communications. Our research group is poised to meet these challenges by developing highly-functional photonic integrated circuits (PICs) and efficient high-speed vertical cavity surface emitting lasers (VCSELs) for advanced fiber optic communications and sensor networks as well as for use in optical interconnects.
Our PICs have demonstrated mode and phase locking, programmability in amplitude, phase and wavelength as well as electro-optic beam steering -- all in a monolithically integrated platform. Our recent work on VCSELs have led to devices that operate >35 Gb/s while using only 286 fJ/bit, and more recently, the first demonstration of gain modulation in a VCSEL using carrier separation as well as high extinction polarization-switching VCSELs.
We focus on all aspects of the design process from simulation and epitaxial design to fabrication and system testing. In addition, our capability of growing high quality GaAs, and InP based material in-house gives us a unique perspective in our research.
Areas of Interest:
In the Rodwell group, we explore the boundaries of high-frequency transistor fabrication and integrated circuit design. Unlike the microelectronics industry, which uses silicon for their transistors, we use elements such as gallium, indium, arsenic, and phosphorus. By using elements from column III and column V of the periodic table, we can create high performance heterojunction bipolar transistors (HBT) and field effect transistors (FET) using InP and InGaAs.
High performance HBTs are required for high speed digital logic and mixed signal circuits enabling sub-mm wave and THz ICs for imaging, sensing, radio astronomy and spectroscopy applications. HBTs designed and fabricated in the group have demonstrated power gain cut-off and current gain cut-off frequencies in excess of 800 and 650 GHz respectively.
Moore’s Law has kept the pace in personal computing for close to 40 years using silicon metal-oxide-semiconductor field effect transistors (MOSFETs). We leverage thirty years of experience in the III-V Arsenide/Phosphide materials system to build MOSFETs using InGaAs. Using technology such as atomic layer deposition (ALD) for gate dielectrics and molecular beam epitaxy (MBE) growth for low resistance self-aligned ohmic contacts, we can create transistors w/ unprecedented performance characteristics.
The group is actively researching devices at all levels: fundamental semiconductor physics and material design; fabrication techniques in our state-of-the-art cleanroom; cutting edge circuit design; and fully integrated system designs. This level of vertical integration allows the students to intelligently guide research for the world’s future technological demands.