NanoTechnology: Materials, Processes & Devices

Research that includes:

  • Development of nanostructure fabrication technology
  • Nanomagnetics, Microphotonics
  • CMOS Integrated Nanowires/Nanotubes (CMOS-Inn)

BPN963: Ordered Porous RGO/SnO2 Thin Films for Ultrasensitive Humidity Detection

Zhou Li
Isaac Zakaria
2022

SnO2-based chemiresistive gas sensors can effectively detect combustible, explosive and toxic gases, and have been widely used in safety monitoring and process control in residential buildings, in various industrial settings and in mines. However, sensitivity and selectivity are still needed to be further improved for most current SnO2-based gas sensors. In addition, their high power consumption due to their high working temperature (200-400°C) limits their further development. Graphene, due to its unique characteristics (such as excellent electrical conductivity, large surface...

Synthesis and Gas Sensing Properties of NiO/ZnO Heterostructured Nanowires

Sikai Zhao
Yanbai Shen
Yong Xia
Aifei Pan
Zhou Li
Carlo Carraro
Roya Maboudian
2021

In this study, we report on the synthesis of the NiO/ZnO heterostructured nanowires by a facile two-step liquid phase route and their gas sensing characteristics employing Au interdigitated electrodes integrated on a miniature ceramic heater. Microstructural characterizations indicate that flocculent NiO particles are uniformly assembled on the outer surfaces of the single-crystalline ZnO nanowires, with diameters around 50 nm and lengths ranging from 500 nm to several μm. The gas sensing investigation indicates that the sensors based on NiO/ZnO heterostructured nanowires exhibit high...

In-Situ Synthesized N-Doped ZnO for Enhanced CO2 Sensing: Experiments and DFT Calculations

Yong Xia
Aifei Pan
Ya-Qiong Su
Sikai Zhao
Zhou Li
Adrian K. Davey
Libo Zhao
Carlo Carraro
Roya Maboudian
2022

Chemiresistive CO2 sensing is attractive due to low cost and ease of chip-level integration. Our previous studies (Yong Xia, 2021) showed the well-developed ZnO material fabricated by in-situ annealing exhibited good CO2 sensing performance. Here, we have expanded on those studies, including CO2 cyclic tests under both dry air and N2 background whereby a much higher response to CO2 in N2 background was observed. Detailed density functional theory calculations were conducted to understand the behavior. The results indicated nitrogen doping is mainly responsible for the observed response. In...

A New Chemresistive NO2 Sensing Material: Hafnium Diboride

Sikai Zhao
Yong Xia
Steven DelaCruz
Aifei Pan
Zhou Li
Yanbai Shen
Marcus A. Worsley
Carlo Carraro
Roya Maboudian
2022

While metal oxides and metal sulfides have been extensively studied for gas sensing applications, there are no extensive reports on gas sensing properties of metal diborides. Here, for the first time, we have investigated the conductometric gas sensing behavior of HfB2 nanoparticles. The HfB2 nanoparticles is synthesized via a sol-gel method and characterized using X-ray diffraction, field emission scanning electron microscopy, transmission electron microscopy, and X-ray photoelectron spectroscopy. The gas sensor is fabricated by drop casting the HfB2 nanoparticles on interdigitated Ag/Pd...

BPN704: Vapor-Liquid-Solid Growth of Polycrystalline Indium Phosphide Thin Films on Metal

Wenbo Ji
2021

Here, we develop a technique that enables direct growth of III-V materials on non-epitaxial substrates. Here, by utilizing a planar liquid phase template, we extend the VLS growth mode to enable polycrystalline indium phosphide (InP) thin film growth on Mo foils.

BPN935: Low Temperature Deposited Thin Films for p-Type Field Effect Transistors and Circuits

Chunsong Zhao
2021

Developing low-temperature grown semiconducting films is critical for the development of flexible, transparent and three-dimensional monolithic integrated electronics, however, low processing temperature typically results in a poor crystallinity and a low mobility. Here, we report the realization of low-temperature fabrication of highly crystalline tellurium films with large grain size (average grain area of ~150 um2) by controlling the crystallization process of thermally evaporated Te films. Tellurium single crystals with a lateral dimensional of 6 um are realized on various...

BPN964: Metal Oxide Heterostructure Nanowires for Gas Sensing Applications

Sikai Zhao
2021

Metal oxide semiconducting gas sensors are one of the most widely used gas sensing devices due to their low cost, high reliability, solid-state, and high response. While they have been employed for the detection of various gases and in many applications, several issues remain including their limited selectivity and humidity interference. As the core part of a semiconducting gas sensor, sensing materials play the key role in determining the sensing performance of the device, with the materials’ microstructure and surface properties being the dominant factors. Thus the primary...

Javey Lab: Researchers Demonstrate New Semiconductor Device Possibilities using Black Phosphorus

August 11, 2021
William Schulz

Stress and strain, applied in just the right manner, can sometimes produce amazing results.

That is what researchers, led by a team at UC Berkeley’s Department of Electrical Engineering and Computer Sciences, discovered about an emerging semiconductor material — black phosphorus (BP) — used to make two types of optoelectronic devices: light emitting diodes (LEDs) and photodetectors.

Under mechanical strain, BP can be induced to emit or detect infrared (IR) light in a range of desirable wavelengths — 2.3 to 5.5 micrometers, which spans the short- to mid-wave IR — and to do so...

Amine-Functionalized Metal-Organic Framework ZIF-8 toward Colorimetric CO2 Sensing in Indoor Air Environment

Adrian K. Davey
Xiang Gao
Yong Xia
Zhou Li
Matthew N. Dods
Steven DelaCruz
Aifei Pan
Sanket Swamy
David Gardner
Carlo Carraro
Roya Maboudian
2021

Carbon dioxide (CO2) has been shown to contribute to human health consequences indoors, such as shortness of breath, nasal and optic irritation, dizziness, and nausea. In this work, we explore the potential of metal–organic frameworks (MOFs) as highly-porous, crystalline sorbents for sensitive colorimetric CO2 detection. In particular, the zeolitic imidazolate framework (ZIF-8) is chosen as the sorptive material due to its chemical stability and tunable CO2 affinity. The colorimetric gas sensor is developed in methanol with three components: (i) MOF ZIF-8 as a high surface area adsorbent...

BPN492: Integrated Microfactory for Nanostructure Synthesis

Eric Lee
SoonGweon Hong
2009

A microfluidic device for high-throughput synthesis of silver and gold nanostructures will be developed. We will design and fabricate microsystems that can simultaneously perform hundreds of reaction conditions on one chip with extreme precision and control. This will greatly improve the tunability of each reaction condition allowing for us to tailor the reaction conditions to synthesize nanostructures with controllable plasmon shifts. Hollow metal particles will be prepared based on a galvanic replacement reaction, which is a method driven by the electrical potential difference...