Ali Javey (Advisor)

Research Advised by Professor Ali Javey

Javey Group:  List of Projects | List of Researchers

BPN634: Low Voltage and Fast Response Actuators

Zhibin Yu
2013

The conventional electrostatic actuators are operated at very high voltage relative slow response which prevents them from useful applications in providing mobility for making microrobots. There has been a lot of study on making electrostatic actuators based on polymers such as acrylic elastomers, HS3 silicone and silicon NuSil. All these materials need over one thousands volts to operate. We are going to make low operation voltage and fast response actuators using nanowire polymer composites. We are going to deposit polymer thin films on vertically aligned nanotube (nanowire) forest...

BPN625: Direct Growth of High Quality III-V Semiconductors on Metal Foils for Low-Cost, High-Efficiency PVs

Maxwell S. Zheng
Zhibin Yu
Rehan Kapadia
2013

The intrinsic advantages of III-V semiconductors for solar cells have been hobbled by the lack of low-cost substrates and processes, which has thus far limited market success of III-V solar cells. Here at Berkeley we are exploring a non-traditional approach which addresses these drawbacks. High optical quality polycrystalline InP films have been grown on non-epitaxial molybdenum substrates. Remarkably, these films with micron-sized grains have similar photoluminescence qualities as single- crystalline InP, and show great promise for high-efficiency, low-cost solar cells....

BPN750: Multi-Gas Detecting Chemical Sensor Platform

Hiroshi Shiraki
2014

Chemical sensitive field effect transistors (CS-FET), which are conventional MOSFETs without gate electrodes will be fabricated and applied for low energy consumption, highly sensitive, small size, multi-gas detecting chemical sensors. The work functions of transition metal oxides (TMOs) deposited onto the channels of the CS-FETs can be manipulated by the adsorption of chemicals onto their surfaces. These changes cause a change in the surface potential of the underlying Si channel, leading to the current modulation of the devices. By selecting appropriate TMOs, different chemicals...

BPN755: Carrier-Selective Oxide Contacts for Silicon Electronics

Corsin Battaglia
Xingtian Yin
Steven Chuang
Thomas Rembert
Hiroshi Shiraki
2014

Efficient carrier selective contacts are key to electronic devices based on silicon including sensors, microelectromechanical systems, field effect transistors and photovoltaics. We explore substoichiometric molybdenum trioxide (MoOx, x<3) as a dopant-free, hole-selective contact for silicon. As a proof of principle, we demonstrate a silicon solar cell with a MoOx hole contact delivering a high open-circuit voltage of 711 mV and a power conversion efficiency of 18.8%. Due to the wide band gap of MoOx, we observe a substantial gain in photocurrent of 1.9 mA/cm2 in the ultraviolet...

BPN698: Multifunctional Electronic Skin

Kevin Chen
2014

Flexible sensor networks have promising applications in fields such as touch sensors for touch sensitive prosthetics and wearable medical diagnosis devices. In this project, we aim to fabricate a multifunctional “e-skin” capable of detecting multiple forms of stimuli including light and pressure, so as to be able to mimic the human skin and beyond. Polyimide is spun onto a silicon wafer upon which traditional CMOS technology is used to fabricate flexible thin film transistors based on solution deposited carbon nanotube networks. Various types of sensors are then integrated to create...

BPN748: Highly Sensitive Electronic Whiskers Based on Patterned Carbon Nanotube and Silver Nanoparticle Composite Films

Zhibin Yu
2014

Mammalian whiskers present an important class of tactile sensors that complement the functionalities of skin for detecting wind with high sensitivity and navigation around local obstacles. Here, we developed electronic whiskers based on highly tunable composite films of carbon nanotubes and silver nanoparticles that are patterned on high-aspect ratio elastic fibers. The nanotubes form a conductive network matrix with excellent bendability, while nanoparticle loading enhances the conductivity and endows the composite with high strain sensitivity. The resistivity of the composites is...

BPN752: Highly Efficient and Stable Photocathode for Solar Hydrogen Production

Yongjing Lin
Corsin Battaglia
Joel W. Ager
2014

Solar hydrogen production by photoelectrochemical water splitting holds great promise for efficient solar energy harvesting and storage. To achieve spontaneous water splitting, developing efficient photoelectrodes with both high photovoltage and high photocurrent is highly desirable. However, current studied photocathodes such as p-Si, p-Cu2O and p-GaP have photovoltage lower than half of 1.23 V, the minimum voltage required for water splitting. To overcome these challenges, we are currently developing a photocathode using amorphous Si thin film with TiO2 encapsulation layer for...

BPN792: Thin Film InP Photoelectrochemical Cells for Efficient, Low-Cost Solar Fuel Production

Mark Hettick
Maxwell Zheng
2015

While bulk p-type InP wafers have produced high efficiency photoelectrochemical water- splitting cells, the high cost of epitaxial substrates limits viability at a larger scale. Here, we utilize low-cost growth of InP on non-epitaxial substrates with the thin-film vapor- liquid-solid method to provide high efficiency, scalable photocathode cells for the hydrogen evolution reaction.

Project end date: 08/19/15

BPN712: Bridging Research-to-Commercialization Gaps In an Industry/University Ecosystem

John Huggins
Hossain M. Fahad
Hiroshi Shiraki
David Burnett
Nicola Accettura
2015

Some BSAC members have, in our surveys and at IAB meetings, vocalized that we need to help bridge commercialization gaps and increase the speed of commercialization. Traditional University research commercialization paths through passive licensing to start-ups, are often highly successful and will remain the dominant path. But such paths do not leverage the sophisticated manufacturing, marketing, and sales channels of our larger Industrial members who could rapidly exploit certain research discoveries. While any such commercialization facilitation programs cannot compromise the...

BPN776: Wearable Electronic Tape

Hiroki Ota
Kevin Chen
2015

We demonstrate a high-performance wearable piezoelectric electronic-tape (E-tape) for motion sensing based on a carbon nanotube (CNT)/silver nanoparticle (AgNP) composite encased in PDMS and VHB flexible thin films. E-tape sensors directly attached to human skin exhibit fast and accurate electric response to bending and stretching movements which induce change in conductivity with high sensitivity. Furthermore, E-tape sensors for a wide range of applications can be realized by the combination of controlling the concentration of AgNPs in the CNT network and designing appropriate...