Photonic Integrated Circuits
The Integrated Circuits Lab is a dynamic and innovative research environment dedicated to advancing the field of microelectronics and integrated circuit design. Our research area focuses on pushing the boundaries of semiconductor technology, exploring novel design techniques, and developing cutting-edge electronic devices and systems. Our interdisciplinary team of researchers collaborates to tackle complex challenges in the design, fabrication, and testing of integrated circuits, fostering innovation and contributing to the development of the electronics industry. Through our work, we strive to shape the future of microelectronics and empower the digital revolution.
SiGeSn-based Heterostructures for Intersubband Photonic Materials
We propose research into lattice-matched Ge/SiGeSn heterostructures as a new material system for n-type intersubband (ISB) optoelectronic devices in the infrared and terahertz spectral range. The motivation lies in the fact that such group-IV semiconductors are non-polar, which results in a dramatically different character of the optical phonon interactions compared with III-V heterostructures widely used for ISB devices. For example, (a) there is dramatically reduced intersubband electron-phonon scattering and (b) a drastic reduction of the absorption of light by optical phonons associated with the Reststrahlen band. This leads to predictions of THz quantum-cascade lasers that operate with low-threshold at room temperature; high-sensitivity quantum-well infrared photodetectors that may compete with MCT detectors in the mid-wave infrared; the ability to newly reach the far-infrared wavelengths of 30-60 μm not accessible with III-Vs. Unlike previous work on p-type SiGe intersubband materials, the Ge/SiGeSn material system is predicted to support n-type intersubband transitions in the L-valley; unlike recent work on strained n-type Ge/SiGe intersubband materials, the Ge/SiGeSn material is predicted to be growable in lattice-matched compositions. However, many material and bandstructure properties remain unknown; fundamental work on growth techniques and optical properties is needed to see if such predictions can be realized experimentally. This line of research leverages recent advances in group-IV SiGeSn material research for interband devices (e.g. infrared diode lasers, LEDs, photodetectors).
References:
1. G. Sun, H. H. Chenga, J. Menéndez, J. B. Khurgin, and R. A. Soref, “Strain-free Ge/GeSiSn quantum cascade lasers based on L-valley intersubband transitions,” Appl. Phys. Lett. 90, 251105 (2007). http://dx.doi.org/10.1063/1.2749844.
2. E. Loewenstein, D. R. Smith, and R. L. Morgan, “Optical-Constants of Far Infrared Materials .2. Crystalline Solids,” Applied Optics 12, 398-406 (1973).
3. E. D. Palik, ed. Handbook of Optical Constants of Solids (Academic Press, 1998).
TriWave Sensor Board Project
Developing a PCB that will be attached to an infrared sensor that is currently being used for an infrared camera. The current camera design consists of multiple boards that take the signals from the sensor and process them into a digital image. This project takes the sensor board and processing board and combines all the functionality into one PCB that will be connected via USB to process the image. With the TriWave Sensor Board project, we want to lower the number of boards needed in the camera to receive a digital image. In the future, this project will turn into a board that processes the signals from the sensor and shows the image all in one unit. The goal of this project is to create a PCB that can be modified and used to test new sensors and optimize the current design of the camera.
Sapphire As a Transformative High-performance Self-consistent IMWP Platform
We propose to utilize sapphire as a transformative high-performance self-consistent IMWP platform. The significant intellectual merit of proposed sapphire platform lies in its feasibility for a fully integrated solution to include a complete set of components with light source, modulator, light detection, passive devices, CMOS control circuit, Silicon on Sapphire (SOS) circuit all-in-one sapphire platform to achieve high-performance low-cost mixed-signal optical links. The proposed sapphire platform utilizes the mature SOS CMOS and RF high frequency circuit technology featuring low power consumption. This project focuses on the development of sapphire based lasers and passive device building blocks including waveguides (straight and bend), splitters, couplers, and ring resonators. A general point-to-point RF-photonics link includes transceivers at each end connected by a fiber. Each transceiver could be seen as a complete IMWP chip with different functional building blocks such as CMOS control circuits, lasers, optical modulators, waveguides, photodetectors, and integrated photonics components for signal processing and input/output. The ultimate chip architecture would enable the optimized overall chip performance. For active components, sapphire substrate is more favorable for the integration of III-V materials compared with using Si substrates due to a closely matched CTE with III-V material systems. For passive components, ultra-low-loss waveguides could be obtained using silicon nitride on sapphire substrate. The basic building block for all passive components is a low-loss waveguide. The optical confinement is determined by the refractive index difference between the light guiding layer and the surrounding layer, while the loss is determined by the material absorption if the waveguide structure design is optimized.