Ali Javey (Advisor)

Research Advised by Professor Ali Javey

Javey Group:  List of Projects | List of Researchers

BPN947: High-Performance Mid-Infrared Optoelectronics

Shu Wang
Naoki Higashitarumizu
Shogo Tajima
2024

Black phosphorus has emerged as a unique optoelectronic material, exhibiting tunable and high device performance from mid-infrared to visible wavelengths. Understanding the photophysics of this system is of interest to further advance device technologies based on it. Here we report the thickness dependence of the photoluminescence quantum yield at room temperature in black phosphorus while measuring the various radiative and non-radiative recombination rates. As the thickness decreases from bulk to ~4 nm, a drop in the photoluminescence quantum yield is initially observed due to enhanced...

BPN983: Materials and Devices for Bright UV LEDs

Shu Wang
2023

Wide band gap semiconductors are crucial for applications in power electronics, displays, solid-state lightning and many other fields. Due to their intrinsic structure and electronic properties, many wide band gap semiconductors can not be intentionally doped as desired, which limits their role in electronic and optoelectronic devices. In this project, we propose tuning the optoelectronic properties of wide band gap semiconductors electrically to enhance its luminescence efficiency.

Project ended: 02/07/2024

I K M Reaz Rahman

Graduate Student Researcher
Electrical Engineering and Computer Sciences
Professor Ali Javey (Advisor)
Ph.D. 2026 (Anticipated)

I K M Reaz Rahman is a Ph.D. candidate in the Electrical Engineering and Computer Sciences department at UC Berkeley, working under the supervision of Professor Ali Javey. He received a Master’s degree in 2020 and a Bachelor’s degree in 2017, both in Electrical and Electronic Engineering at Bangladesh University of Engineering and Technology.

Before joining UC Berkeley, Reaz worked on modeling of nanoscale transistors and their impact with scaling. At present, his focus is on characterization of optoelectronic properties in low-dimensional systems.

...

Jamie Geng

Graduate Student Researcher
Electrical Engineering and Computer Sciences
Professor Ali Javey (Advisor)
Ph.D. 2028 (Anticipated)

A Color-Tunable Alternating Current Organic Light Emitting Capacitor

Jongchan Kim
Vivian Wang
Seung Chan Kim
Jun Yeob Lee
Ali Javey
2023

We demonstrate an alternating current (AC) driven light emitting capacitor in which the color of the emission spectra can be changed via an applied AC frequency. The device has a simple metal-oxide-semiconductor (MOS) capacitor structure with an organic emissive layer, enabling facile fabrication processing. The organic emissive layer comprises a thin, submonolayer low energy dye layer underneath a thick host matrix (∼30 nm) with higher energy emitting dyes. The emission of the lower energy dyes dominates at low frequency, while the higher energy emission of the host matrix dominates at...

Highly Multicolored Light-Emitting Arrays for Compressive Spectroscopy

Vivian Wang
Shiekh Zia Uddin
Junho Park
Ali Javey
2023

Miniaturized, multicolored light-emitting device arrays are promising for applications in sensing, imaging, computing, and more, but the range of emission colors achievable by a conventional light-emitting diode is limited by material or device constraints. In this work, we demonstrate a highly multicolored light-emitting array with 49 different, individually addressable colors on a single chip. The array consists of pulsed-driven metal-oxide-semiconductor capacitors, which generate electroluminescence from microdispensed materials spanning a diverse range of colors and spectral shapes,...

Long Operating Lifetime Mid-Infrared LEDs Based on Black Phosphorus

Naoki Higashitarumizu
Shogo Tajima
Jongchan Kim
Mingyang Cai
Ali Javey
2023

Black phosphorus (BP) is a narrow bandgap layered semiconductor promising for mid-infrared optoelectronic applications. BP-based devices have been shown to surpass state-of-the-art mid-infrared detectors and light-emitting diodes (LEDs) in terms of performance. Despite their device advantages, the material’s inherent instability in the air could hinder its use in practical optoelectronic applications. Here, we investigated the impact of passivation on the device lifetime of BP LEDs, which deteriorate in a matter of seconds without using passivation. The lifetime is significantly extended...

Gated Photoluminescence of Colloidal Quantum Dots

I K M Reaz Rahman
2023
Fall 2023 BSAC Research Review Presentation

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Project: BPN988 - Ali Javey Group

Seung-Rok Kim

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

Seung-Rok Kim is a postdoctoral research associate in Electrical Engineering and Computer Sciences at the University of California, Berkeley, a postdoctoral researcher at Berkeley Sensor & Actuator Center (BSAC), and a research affiliate in the Materials Science Division at Lawrence Berkeley National Laboratory with a joint appointment. He received a Ph.D. in Materials Science and Engineering from Yonsei University in 2021, and was a postdoctoral research associate and research professor at Yonsei University in 2021 and 2023. Seung-Rok Kim then joined Javey...

BPN920: Robust, Multimodal Sweat Sensors with High-Throughput Fabrication

Noelle Davis
Ashwin Aggarwal
Sorour Darvishi
2023

In the field of sweat monitoring, many sensors have been piloted with one or two subjects over limited periods of time, but there is a need for prolonged, large-scale studies to establish reliable physiological correlations that account for diverse subjects, activities, and environments. Chemical sensors provide the concentration of analytes of interest, including sodium, potassium, and glucose, while sweat rate sensors provide standalone information on nerve function and hydration. Monitoring both of these in parallel will enable the decoding of concentrations of analytes that are...