Ali Javey (Advisor)

Research Advised by Professor Ali Javey

Perfectly Bright Two-Dimensional Semiconductors

Shiekh Zia Uddin
2022
Spring 2022 BSAC Research Review Presentation View Slides View Presentation

Defects in conventional semiconductors substantially lower the photoluminescence (PL) quantum yield (QY), a key metric of optoelectronic performance that directly dictates the maximum device efficiency. Two-dimensional transition-metal dichalcogenides (...

BPN920: Sweat Rate Sensors with High-Throughput Fabrication

Noelle Davis
Jonghwa Park
2022

While recent sweat analysis has overwhelmingly focused on measuring biomarker concentrations, one of the most physiologically informative parameters is actually sweat secretion rate. Sweat rate is important to track as it modulates the concentrations of secreted analytes, but even stand-alone it can indicate evolving or unfavorable health conditions including cardiac complications, nerve damage, and dehydration. Precise and continuous sweat sensors are therefore an important component of wearable sweat sensing technology. Various sensing schemes and form factors can be used for sweat rate...

BPN931: Multiplexed Electroluminescent Device for Emission from Infrared to Ultraviolet Wavelength

Vivian Wang
Junho Park
2022

Using electroluminescence as a metrology method could have many advantages for on-chip characterization of chemical composition, where the need for an on-chip light source can be eliminated and materials with different excitation energies can be characterized by the same device. However, the range of materials that can be used in electroluminescent devices is typically limited due to challenges related to material processing and band alignment. In this project, we aim to develop a multiplexed electroluminescent device that can produce electroluminescence from infrared to ultraviolet...

BPN971: Bright Mid-Wave Infrared Light-Emitting Diodes Based on Black Phosphorus

Niharika Gupta
2022

The mid-wave infrared (MWIR) wavelength range plays a central role in a variety of applications, including optical gas sensing, industrial process control, spectroscopy, and infrared (IR) countermeasures. Among the MWIR light sources, light-emitting diodes (LEDs) have the advantages of simple design, room-temperature operation, and low cost. Owing to the low Auger recombination at high carrier densities and direct bandgap of black phosphorus (bP), it can serve as a high quantum efficiency emitting layer in LEDs. In this work, we demonstrate bP-LEDs exhibiting high external quantum...

Shu Wang

Graduate Student Researcher
Materials Science and Engineering
Professor Ali Javey (Advisor)
Ph.D. 2026 (Anticipated)

BPN946: Sensor for Natural Sweat Analysis

Jonghwa Park
Shu Wang
Noelle Davis
2022

Wearable sweat sensors have emerged as attractive platforms for non-invasive health monitoring. While most sweat sensors have relied on exercise or chemical stimulation to generate sweat, natural thermoregulatory sweat is an attractive alternative as it can be accessed during routine and even sedentary activity without impeding user lifestyles, while also potentially preserving correlations between sweat and blood biomarkers. For rapid accumulation of natural sweat that enables quick, single-point measurement of sweat analytes, we develop a simple, glove-based sensing platform to capture...

BPN947: Dynamic Spectrum Optoelectronics with Black Phosphorus

Naoki Higashitarumizu
2022

Traditionally, the wavelength range where room-temperature, infrared optoelectronic devices operate is tuned by changing the composition of semiconductor alloys during growth, but it is fixed once fabricated. Although the wide, dynamic, and reversible tuning of the operating wavelength range after fabrication is a highly desirable feature in various applications, no such platform has been developed yet in the infrared range. Here, we present black phosphorus (bP) as an ideal candidate for infrared optoelectronics with dynamically variable spectrum, owing to the extraordinary...

BPN925: Perfectly Bright Low Dimensional Semiconductors

Shiekh Zia Uddin
Jongchan Kim
2022

Most optoelectronic devices operate at high photocarrier densities, where all semiconductors suffer from enhanced nonradiative recombination. Nonradiative processes proportionately reduce photoluminescence (PL) quantum yield (QY), a performance metric that directly dictates the maximum device efficiency. Although transition metal dichalcogenide (TMDC) monolayers exhibit near-unity PL QY at low exciton densities, nonradiative exciton-exciton annihilation (EEA) enhanced by van-Hove singularity (VHS) rapidly degrades their PL QY at high exciton densities and limits their utility in...

Shiekh Zia Uddin

Graduate Student Researcher
Electrical Engineering and Computer Sciences
Professor Ali Javey (Advisor)
Ph.D. 2022 (Anticipated)

Shiekh Zia Uddin received his Bachelors in Science degree in Electrical and Electronics Engineering from Bangladesh University of Engineering and Technology (BUET). In his undergraduate, he worked on both biomedical signal processing and nanophotonics. His current research is on photophysics and optoelectronics of low dimensional semiconductors.