Publications

Micromachined Hot-Filament Vacuum Devices

Kirt R. Williams
Richard S. Muller
1997
We describe investigations on micromachined hot-filament vacuum devices, which are electronic devices made by micromachining an ohmically heated tungsten filamentthat acts as a source of blackbody-like radiation or of free electrons. The freestanding filaments, which are typically 200-500μm long, 5-20μm wide, and 0.7-2.3μm thick, are suspended over a cavity...

Micromachined Vibratory Rate Gyroscopes

William A. Clark
Roger T. Howe
1997
A vibratory rate gyroscope has been developed and implemented using a micromachined mechanical element and integrated circuitry on the same silicon substrate. The mechanical element is a proof mass suspended by springs which is driven into lateral ...

Electromechanical Characterization of Microresonators for Circuit Applications

Clark T.-C. Nguyen
Roger T. Howe
1991
The design of circuits incorporating microresonators which utilize electrostatic drive and sense is accompanied by a need for a convenient method to experimentally extract the circuit elements modelling the microresonators. Previously, techniques which electrically detect microresonator motional current ...

Micromechanical Signal Processors

Clark T.-C. Nguyen
Roger T. Howe
1994
Completely monolithic high-Q micromechanical signal processors constructed of polycrystalline silicon and integrated with CMOS electronics are described. The signal processors implemented include an oscillator, a bandpass filter, and a mixer+filter-all of which are components commonly required for up-...

Micromechanisms Using Sidewall Beams

Michael Judy
Roger T. Howe
1994
A process technology is developed for surface micromachining that achieves sub-micrometer linewidths without the use of advanced lithography equipment. This technique is based upon the sidewall spacer technique that has been used extensively in integrated circuits. The sidewall spacer technique, stated simply, is to deposit a conformal film over a vertical step on the substrate. The conformal film is then anisotropically etched leaving a siclewall spacer or beam. Traditionally these sidewall "stringers" were a nuisance in surface micromachining great care had to be expended to remove...

Single-Pixel Reconstructive Mid-Infrared Micro-Spectrometer

Kaichen Dong
Jiachen Li
Tiancheng Zhang
Fangda Gu
Yuhang Cai
Niharika Gupta
Ali Javey
Jie Yao
Junqiao Wu
2023

Miniaturized spectrometers in the mid-infrared (MIR) are critical in developing next-generation portable electronics for advanced sensing and analysis. The bulky gratings or detector/filter arrays in conventional micro-spectrometers set a physical limitation to their miniaturization. In this work, we demonstrate a single-pixel MIR micro-spectrometer that reconstructs the sample transmission spectrum by a spectrally dispersed light source instead of spatially grated light beams. The spectrally tunable MIR light source is realized based on the thermal emissivity engineered via the metal-...

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...

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...

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...

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,...