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Jiao Lab

Current research projects in the Jiao Lab span from the development of nanofabrication techniques for property-controlled growth of graphene and its metal oxide hybrids, nanotubes, nanowires, and nanocrystals for use in nanoelectronic devices with the potential for industrial applications, to the use of nanoscale materials and devices for biomedical applications as well as for water purification. 

Two Graduate Research Assistantships available in Jiao Lab for research focused on materials science and engineering. More details here

Dr. Jiao is committed to mentoring and supervising graduate students and new researchers. Her labs provide a wide range of opportunities for both graduate and undergraduate research. Dr. Jiao has been serving as the Director of the Center for Electron Microscopy and Nanofabrication at Portland State University, and as the Principle Investigator (PI) for several NSF and high-tech company funded research projects and an NSF-funded REU site since 2001. The results of her research are documented in more than 270 publications and five issued patents.

Some of the representative research projects are summarized below:

Fabrication and Characterization of Wafer-Scale Chemical Vapor Deposition Graphene for Spintronics Applications

  • This project focuses on graphene as a material used for solid-state electronic devices and the development of their fabrication techniques, specifically on the refinement of the growth processes of epitaxial CVD graphene and its characterization. Quality graphene—characterized by mono-layer, large crystalline size, and minimal defects—can be grown by controlling specific growth parameters including substrate material and crystal structure, ratio of precursors, reaction temperature and pressure, and the use of plasma to drive the reaction, etc. To evaluate graphene quality, structural characterization is carried out through Raman Spectroscopy, AFM/STM, and TEM/EDX. The goal of the research is to develop optimized conditions for high-quality graphene growth. To characterize graphene spintronic properties, novel hybrid diffusion drift spin valve (HDDSV) arrays were designed and fabricated. The newly designed device aims at allowing systematic investigations of graphene spin transport parameters including spin lifetime, spin diffusion length, and polarization injection efficiency by variations of device components and dimensions. It is expected that the novel HDDSVs are capable of detecting nonlocal signals originating from a spin accumulation of spin polarized charge carriers, which occurs away from the influence of ferromagnetic (FM)/tunnel barrier (TB)/Graphene interfaces. Characterization of these devices will enable us to establish the device parameter and material effects.

Investigation of Low-Temperature Growth Parameters for Scalable Graphene Films Suitable for Graphene-Based Silicon–CMOS Applications

  • This project aims at developing a scalable technique for low-temperature (within 400°C~600°C) growth of graphene with controlled properties by a chemical vapor deposition (CVD) process. A systematic experimental investigation is carried out in three CVD systems (a traditional CVD, a plasma enhanced CVD, and inductively coupled plasma CVD) with varied functionality to implement different growth parameters. The results are comparatively analyzed. It is our intention to establish the correlations of the synergistic effects among the growth parameters. This will lead to the identification of optimal parameters for direct deposition of graphene films that could be readily integrated with the silicon and complementary-metal-oxide-semiconductor (CMOS) process for nanoscaled electronic fabrication and continued device scaling.

Sustainable Groundwater Treatment using Granular Activated Carbon (GAC) Supported Bimetal Catalysts

  • This project aims to design and fabricate a novel class of GAC-supported bimetal catalysts that provide rapid contaminant degradation without accumulation of problematic byproducts or significant susceptibility to poisoning the catalysts by common components of groundwater. The fabrication procedures developed for these catalysts are cost-effective and scalable to mass production without requiring or generating hazardous materials. The protocols and data developed to assess the reactivity of these catalysts will expand the scope of catalytic hydrogenation processes for water treatment from typical hydrodehalogenation (HDH) and hydrodeoxygenation (HDO) substrates to a more diverse range of contaminants of emerging concern.

Efficiency Enhancement of Photocatalytic Water Purification using 3D Optical Material

  • Photocatalytic water purification is a scientific technique for the destruction of organic pollutants using light. This technology is based on the presence of a semiconductor that can be excited by light with an energy higher than its band gap, inducing the formation of energy-rich electron-hole pairs that can be involved in redox reactions. Recent progress has explored the chemical nature of nanoscale semiconductors with the object of improving their electronic and optical properties. This project aims to enhance the semiconductor’s photoresponse to visible light through the design and fabrication of 3D structures that optimize optical and electrical characteristics of the photocatalyst and reduce energy losses due to parasitic photon absorption and charge carrier recombination. 3D photocatalyst cartridges have been created using a chemical synthesis technique, and a continuous flow photoreactor has been designed and built as a means for testing the effectiveness of the material. In order to compare with other photocatalytic purifiers, quantification of the system's Electrical Energy per Order (EEO) is obtained by monitoring the change in concentration of pollutants with an in-line UV-Vis flow spectrometer as the water passes through the reactor. A patent is pending for this development.

Optimization of Carbon Nanotube Gas Sensors 

  • As a quasi-1D structure, the electron transport across carbon nanotubes is highly sensitive to surface chemistry. By using carbon nanotubes (CNTs) as a transport channel in field-effect transistors, this project combines Raman spectroscopy and an ultra-high vacuum probe station to investigate the role that crystalline defects and adsorbed gas molecules play in carbon nanotube electron transport characteristics. This project is not only investigating CNTs’ sensing capabilities but also developing related metrology capabilities to carry out various testing and analyses.

Nanoparticulate Adjuvants and Delivery Systems Towards New Generation Vaccines

  • Vaccination has greatly impacted global public health by controlling and preventing infectious diseases and treating cancer. However, it remains difficult to generate sufficient immunity with vaccines containing insufficient immunogenic antigens. To amplify the interaction between antigens and the immune system, our study has demonstrated that antigen coupled to alumina nanoparticles (NPs) is 500 times more efficiently processed by dendritic cells for major histocompatibility complex (MHC) class I antigen presentation, and elicits strong cytotoxic T cell response against cancer in vivo (Nature Nanotechnology, 2011, 6, 645–50). We now extend these studies to infectious diseases, with the goal of utilizing alumina NPs to elicit cytotoxic T cell response to defined pathogen antigens.