ABSTRACTS
2019 National McNair Scholars Conference at UCLA
Researcher: Trent Garrett
Presentation Title: Synthesis of Low Band Gap Quantum Dots using InxGa1-xAs on InAs(111)A
Research Focus: Tensile strained quantum dots
School: Boise State University
Presentation Type: Oral presentation
Quantum dots (QDs) are a type of nanostructure that can absorb and emit light. By controlling a QD’s size, we can accurately tune the color of light it absorbs and emits. QDs can be synthesized from a variety of semiconductors including GaAs, Ge, and GaN. These materials are deposited onto a wider band gap semiconductor, selected to produce quantum confinement and strain in the system. QDs form spontaneously as a result of the strain, which arises from mismatch between the lattice constants of the two semiconductor crystals. Depending on one’s choice of material system, the strain produced can be tensile or compressive in nature. Tensile and compressive strain affect a semiconductor’s electronic structure in different ways. Tensile and compressive QDs hence exhibit different properties. Tensile-strained QDs (TSQDs) have smaller band gap energy and emit light at a longer wavelength; compressively strained QDs have wider band gaps and emit shorter wavelength light.
Our group is currently exploring the synthesis of narrow band gap InGaAs TSQDs on InAs(111)A buffers. We will present findings on the growth and characterization of InGaAs/InAs(111)A TSQDs grown via molecular beam epitaxy (MBE). Preliminary results show we can produce smooth InAs(111)A layers. By tuning the MBE conditions, we demonstrate control over TSQD structural properties (i.e. height, diameter, and density). We can also engineer TSQDs growth by varying the InGaAs composition to manipulate the tensile strain. We anticipate that these narrow band gap TSQDs will offer a completely new way of obtaining highly tunable infrared light emission.
Researcher: Tonglin Lu
Presentation Title: Development of P-Type NiO Films Using RF Sputtering of a NiO target for PMOS TFT Technology
Research Focus: Solid-State Devices and Nanotechnology
School: University of Michigan
Presentation Type: Poster presentation
Complementary metal–oxide–semiconductor transistors are the fundamental technology used to construct most of the electronic devices in our lives. While n-type metal oxide thin film semiconductors have been well-studied and fully commercialized, p-type thin film transistors (TFTs) have not been as well developed. This work presents the development of p-type NiO films for p-type TFTs technology. The NiO films were deposited using physical vapor deposition (PVD), namely by RF sputtering of a NiO target at room temperature. We ran several experiments varying deposition pressure, ?2: ?? gas ratio, and source power to explore and characterize the NiO films under different deposition conditions. For each experiment, the physical properties of the NiO films have been systematically investigated by ellipsometry, AFM, SEM and XRD measurements. The electrical properties of NiO films have been investigated using Hall effect measurements and van der Pauw resistance measurements. NiO TFTs were also fabricated using the same RF sputtered NiO films at Lurie Nanofabrication Facility at the University of Michigan. The drain current and field effect mobility of the NiO TFTs were measured to characterize the device performance. For future works, further tuning of the NiO film process space and doping will be utilized to further improve TFT performance.
Researcher: Wesley, Sandidge
Presentation Title: Secondary Eclipse Variability of Kepler-76 b
Research Focus:
School: Boise State University
Presentation Type: Oral Presentation
Phase curves and secondary eclipses of gaseous exoplanets are diagnostic of not only atmospheric composition and meteorology, but variations in the phase curves and eclipses over
time may point to variability driven by atmospheric dynamics. The dataset from NASA’s Kepler Mission has accurate photometric precision and spans a period of over 1,000 days, providing an ideal dataset to study Kepler-76 b. Kepler-76 b is a two-Jupiter mass gas giant, with an equilibrium temperature approaching 2,000 K, in a 1.5-day orbit around its star, and the data reveal Kepler-76 b’s secondary eclipse – with a depth of 87±6 parts-per-million (ppm), which corresponds to an effective temperature of 2,830 K. The data also reveals variations in the phase curve for Kepler 76-b secondary eclipse. With an average value of 50.5 ppm and values ranging from 35 ppm to 70 ppm over tens of days.