Ali Javey (Advisor)

Research Advised by Professor Ali Javey

Javey Group:  List of Projects | List of Researchers

Wenbo Ji

Former Graduate Student Researcher
Materials Science & Engineering
Professor Ali Javey (Advisor)
Ph.D. 2022 (Anticipated)

Enhanced Neutral Exciton Diffusion in Monolayer WS 2 by Exciton–Exciton Annihilation

Shiekh Zia Uddin
Naoki Higashitarumizu
Hyungjin Kim
Jun Yi
Xiang Zhang
Daryl Chrzan
Ali Javey
2022
2 ABSTRACT: Dominant recombination pathways in monolayer transition metal dichalcogenides (TMDCs) depend primarily on background carrier concentration, generation rate and applied strain. Charged excitons formed in the presence of background carriers mainly recombine nonradiatively. Neutral excitons recombine completely radiatively at low generation rates, but experience nonradiative exciton-exciton annihilation (EEA) at high generation rates. Strain can suppress EEA resulting in near-unity photoluminescence quantum yield (PL QY) at all exciton densities. Although exciton diffusion is the...

Efficiency Roll-Off Free Electroluminescence from Monolayer WSe2

Shiekh Zia Uddin
Naoki Higashitarumizu
Hyungjin Kim
I K M Reaz Rahman
Ali Javey
2022
Exciton-exciton annihilation (EEA) is a nonradiative process commonly observed in excitonic materials at high exciton densities. Like Auger recombination, EEA degrades luminescence efficiency at high exciton densities and causes efficiency roll-off in light-emitting devices. Near-unity photoluminescence quantum yield has been demonstrated in transition metal dichalcogenides (TMDCs) at all exciton densities with optimal band structure modification mediated by strain. Although the recombination pathways in TMDCs are well understood, the practical application of light-emitting devices has...

Tape-Free, Digital Wearable Band for Exercise Sweat Rate Monitoring

Manik Dautta
Luis Fernando Ayala-Cardona
Noelle Davis
Ashwin Aggarwal
Jonghwa Park
Shu Wang
Liam Gillan
Elina Jansson
Mikko Hietala
Hyunhyub Ko
Jussi Hiltunen
Ali Javey
2023
Monitoring sweat secretion rate is essential for uncovering underlying physical conditions like hyperhidrosis, mental stress, and neural disorders. Often, flexible microfluidic sweat rate monitoring devices use tape as a means of attachment to the skin to tightly seal the collection area. While these single-use, adhesive-backed devices have lightweight and thin interfaces for mounting on the skin, their form factor complicates their potential integration with available commercial wearables, such as smartwatches. Here, a tape-free device, consisting of a 3D-printed sweat collector with a...

Shiekh Zia Uddin Receives the 2022 MRS Graduate Student Gold Award

May 1, 2022

Please join BSAC in congratulating Shiekh Zia Uddin of the Javey group on being awarded the 2022 Materials Research Society (MRS) Graduate Student Gold Award.

The MRS Award recognizes "students of exceptional ability who show promise for significant future achievement in materials research." Uddin works in the areas of photophysics and optoelectronics of low dimensional semiconductors, with a focus on the photophysics of low-dimensional excitonic materials. He was honored for research...

Drug Monitoring with Wearable Sweat Sensors

Li-Chia Tai
2022

Wearable sensors have been very popular among us to monitor our physical wellness, and they are potentially important for health monitoring with implications toward preventive care and clinical treatment. On the market, noninvasive wearables can be used to track external metrics such as heart rate and ECG signal. However, they fail to inform users about elusive biomarkers at the molecular level, which can potentially provide more insight into a person’s health situation. Traditionally, accessing bio-molecular information requires collecting blood or urine samples with invasive extraction...

Manik Dautta

Postdoctoral Researcher
Electrical Engineering and Computer Sciences
Professor Ali Javey (Advisor)
PostDoc 2022

Niharika Gupta

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

Low Voltage AC Electroluminescence in Silicon MOS Capacitors

I K M Reaz Rahman
Shiekh Zia Uddin
Hyungjin Kim
Naoki Higashitarumizu
Ali Javey
2022
Low power silicon based light source and detector are attractive for on-chip photonic circuits given their ease of process integration. However, conventional silicon light emitting diodes emit photons with energies near the band edge where the corresponding silicon photodetectors lack responsivity. On the other hand, previously reported hot carrier electroluminescent silicon devices utilizing a reverse biased diode require high operating voltages. Here, we investigate hot carrier electroluminescence in silicon metal–oxide–semiconductor capacitors operating under transient voltage conditions...

Wearable Biosensors for Body Computing

Yuanjing Lin
Mallika Bariya
Ali Javey
2020
The challenges of growing and aging populations combined with limited clinical resources have created huge demand for wearable and portable healthcare devices. Research advances in wearable biosensors have made it easier to achieve reliable noninvasive monitoring of health and body status. In this review, recent progress in the development of body computing systems for personalized healthcare is presented, with key considerations and case studies. Critical form factors for wearable sensors, their materials, structures, power sources, modes of data communication, and the types of...