Publications

Anomalous Thickness Dependence of Photoluminescence Quantum Yield in Black Phosphorous

Naoki Higashitarumizu
Shiekh Zia Uddin
Daniel Weinberg
Nima Sefidmooye Azar
I K M Reaz Rahman
Vivian Wang
Kenneth B. Crozier
Eran Rabani
Ali Javey
2023

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...

Flexible Vanadium Dioxide Photodetectors for Visible to Longwave Infrared Detection at Room Temperature

Sivacarendran Balendhran
Mohammad Taha
Shifan Wang
Wei Yan
Naoki Higashitarumizu
Dingchen Wen
Nima Sefidmooye Azar
James Bullock
Paul Mulvaney
Ali Javey
2023

Flexible optoelectronics is a rapidly growing field, with a wide range of potential applications. From wearable sensors to bendable solar cells, curved displays, and curved focal plane arrays, the possibilities are endless. The criticality of flexible photodetectors for many of these applications is acknowledged, however, devices that are demonstrated thus far are limited in their spectral range. In this study, flexible photodetectors are demonstrated using a VOx nanoparticle ink, with an extremely broad operating wavelength range of 0.4 to 20 µm. This ink is synthesized using a simple and...

A CMOS Biosensor for Infectious Disease Detection

Turgut Sefket Aytür
Bernhard E. Boser
Kristofer S.J. Pister
Eva Harris
2007

The timely and accurate diagnosis of infectious diseases is indispensable for directing patient management and informing larger public health decisions. For the individual patient, delays in accurate diagnosis may delay necessary treatment and consequently result in a negative outcome. From the public health standpoint, prompt awareness of disease outbreaks is critical for an effective response. In developed countries, both the medical infrastructure and...

Fabrication Tolerant Inverse Design Grating Couplers for Scalable Trapped Ion Quantum Computing

Daniel Klawson
Mizuki Shirao
Sara Mouradian
Ming C. Wu
2022

A fabrication tolerant Si grating coupler for 1.762 µm operation is optimized with inverse design, allowing for −30 dB crosstalk between a pair of 133Ba+ trapped ion qubits within expected fabrication variation.

Ferrite-Rod Antenna Driven Wireless Resoswitch Receiver

Kevin H. Zheng
Qiutong Jin
Clark T.-C. Nguyen
2023

A micromechanical resoswitch receiver coupled to a 23.7-kHz wireless channel via a ferrite-rod
antenna successfully demonstrates short-range wireless reception with resoswitch sensitivity
better than –62 dBm at an on-off keying (OOK) bit rate of 0.9 kbit/s. The demonstrated
performance confirms models that predict the maximum bit rate of such a receiver, revealing an
ability to adapt to bit rates as high as 8 kbit/s sans antenna that surprisingly are not limited
mechanically, but then reduce upon introduction of finite electrical bandwidth antennas. Indeed,
the...

PCB-Less Integration of a Robust Wireless MEMS Tactile Package

Dillon Acker-James
Kristofer S.J. Pister
2023

Creating a wireless tactile actuator the size of an aspirin will allow for more precise physical stimulation. This will lead to a more immersive virtual reality (VR) experience and better convey information via touch. Making this wireless tactile actuator can be accomplished by further utilizing the existing Si on Insulator (SOI) structure. Currently, a printed circuit board (PCB) is used for the sole purpose of assembly, however, further utilization of the Micro Electromechanical Systems (MEMS) SOI structure can allow the chip to operate as both the actuator and housing package. In...

Frequency Compensated Crystal-Free 802.15.4 Wireless Radio

Alex Moreno
Kristofer S.J. Pister
2022

Crystal-Free radios are susceptible to frequency drifts due to temperature and voltage. Compensation for the frequency drift in the 2.4 GHz local oscillator due to voltage variation was demonstrated for a Crystal-Free radio while powered from a solar cell under 200 mW/cm2 of irradiation and a 0805 capacitor. Without compensation the local oscillator frequency would vary by 2.4 MHz while the 802.15.4 packets were transmitted resulting in a loss of 100B of the payload. With frequency drift compensation that oscillator frequency varied less than 300KHz and the full length 125B 802.15.4...

A High Seebeck Coeffiecient Thermoelectric Generator Based on a Self-Healing Ionogel

Yu Long
Peisheng He
Yande Peng
Liwei Lin
2022

In this work, we report a thermoelectric energy harvester based on an ion-conductive ionogel withthree distinctive features as compared with the state-of-art systems: (1) selfhealable in both thematerial and device operations under large deformations; (2) ultrahigh Seebeck coefficient withthe measured value of 7068 μV/K for the material, and 298 μV/K for a prototype energy harvesterin operations; and (3) stable performances under large bending states with little...

Large-scale Silicon Photonics Focal Plane Switch Array for Optical Beam Steering

Xiaosheng Zhang
Kyungmok Kwon
Johannes Henriksson
Jianheng Luo
Ming C. Wu
2021

We report on 128×128-element two-dimensional silicon photonics focal plane switch arrays with microelectromechanical-system optical switches for random-access optical beam steering. A 70°×70° field-of-view and sub-MHz steering speed are experimentally demonstrated.

A Large-Scale Microelectromechanical-Systems-Based Silicon Photonics LiDAR

Xiaosheng Zhang
Kyungmok Kwon
Johannes Henriksson
Jianheng Luo
Ming C. Wu
2022

Three-dimensional (3D) imaging sensors allow machines to perceive, map and interact with the surrounding world1. The size of light detection and ranging (LiDAR) devices is often limited by mechanical scanners. Focal plane array-based 3D sensors are promising candidates for solid-state LiDARs because they allow electronic scanning without mechanical moving parts. However, their resolutions have been limited to 512 pixels or smaller2. In this paper, we report on a 16,384-pixel LiDAR with a wide field of view (FoV, 70° × 70°), a fine addressing resolution (0.6° × 0.6°), a narrow beam...