Publications

A Micromechanical RF Channelizer

Mehmet Akgul
2015

The power consumption of a radio generally goes as the number and strength of the RF signals it must process. In particular, a radio receiver would consume much less power if the signal presented to its electronics contained only the desired signal in a tiny percent bandwidth frequency channel, rather than the typical mix of signals containing unwanted energy outside the desired channel. Unfortunately, a lack of filters capable of selecting single channel bandwidths at RF forces the front-ends of contemporary receivers to accept unwanted signals, and thus, to operate with sub-optimal...

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,...

Chip-Scale Fluorescence Microscope

Efthymios Papageorgiou
Bernhard E. Boser
Mekhail Anwar
Gerard Marriott
2019
CMOS image sensors have been widely used for decades, largely displacing CCDtechnology in cameras, scanners, telescopes, and a variety of medical sensors. Photodiodes are formed in the IC substrate and the technology has been repurposed to make more advanced structures with higher sensitivity, such as pinned or avalanche photodiodes. Less work has gone into generating optical elements using other features of the CMOS process, namely the metal interconnect. The precision deposition and spacing of the metal...

Low Dimensional Materials for Next Generation Electronics

Steven Chuang
Ali Javey
2014

Ever since the invention of the transistor, aggressive channel length scaling has been pursued to achieve higher performance and greater packing density. In order to preserve gate control at short channel lengths, the transistor channel has evolved from bulk to low dimensional substrates, such as 2D thin films and 1D nanowires. For scaling to continue, it is vital that we understand the processing and physics of low dimensional materials.

Chapter 2 focuses on quasi-2D ultrathin body InAsSb-on-insulator n-FETs. III-V materials offer high mobilities for excellent on-state currents,...

Ultrasonic 3D Rangefinder on a Chip

Richard J. Przybyla
Bernhard E. Boser
2013

Optical 3D imagers for gesture recognition, such as Microsoft Kinect, suffer from large size and high power consumption. Their performance depends on ambient illumination and they generally cannot operate in sunlight. These factors have prevented widespread adoption of gesture interfaces in energy- and volume-limited environments such as tablets and smartphones. Gesture recognition using sound is an attractive candidate to overcome these difficulties because of the potential for chip-scale solution size, low power consumption, and ambient light insensitivity.

Our research focuses...

Frequency Modulated Gyroscopes

Mitchell H. Kline
Bernhard E. Boser
2013

MEMS gyroscopes for consumer devices, such as smartphones and tablets, suffer from high power consumption and drift which precludes their use in inertial navi- gation applications. Conventional MEMS gyroscopes detect Coriolis force through measurement of very small displacements on a sense axis, which requires low-noise, and consequently high-power, electronics. The sensitivity of the gyroscope is im- proved through mode-matching, but this introduces many other problems, such as low bandwidth and unreliable scale factor. Additionally, the conventional Coriolis force detection method...

Readout Circuits for Frequency-Modulated Gyroscopes

Igor I. Izyumin
Bernhard E. Boser
2014

In recent years, MEMS gyroscopes have become nearly omnipresent. From their origins in automotive stability control systems, these sensors have migrated to a diverse range of applications, including image stabilization in cameras and motion tracking in videogames and fitness monitors. A key application for MEMS gyroscopes is pedestrian navigation, which can help provide always-on location in portable devices while minimizing power consumption and infrastructure requirements. While modern smartphones have ...

In-Air Rangefinding with an AlN Piezoelectric Micromachined Ultrasound Transducer

Richard J. Przybyla
Stefon E. Shelton
Andre Guedes
Igor I. Izyumin
Mitchell H. Kline
David A. Horsley
Bernhard E. Boser
2011

An ultrasonic rangefinder has a working range of 30 mm to 450 mm and operates at a 375 Hz maximum sampling rate. The random noise increases with distance and equals 1.3 mm at the maximum range. The range measurement principle is based on pulse-echo time-of-flight measurement using a single transducer for transmit and receive. The transducer consists of a piezoelectric AlN membrane with 400 µm diameter, which was fabricated using a low-temperature process compatible with processed CMOS wafers. The performance of the system exceeds the performance of other micromechanical rangefinders.

Integrated Silicon Electromechanical Vapor Sensor

Roger T. Howe
Richard S. Muller
Richard M. White
1984
An integrated vapor sensor is described which is fabricated ona silicon substrateusing conventional NMOS processing steps. It consists of a poly-El mcro- bridge, underlying electrodes for electrostatic excitation and capacitive...