Network


Latest external collaboration on country level. Dive into details by clicking on the dots.

Hotspot


Dive into the research topics where Jiajun Luo is active.

Publication


Featured researches published by Jiajun Luo.


ACS Nano | 2013

Sensing behavior of atomically thin-layered MoS2 transistors.

Dattatray J. Late; Yi Kai Huang; Bin Liu; Jagaran Acharya; Sharmila N. Shirodkar; Jiajun Luo; Aiming Yan; Daniel Charles; Umesh V. Waghmare; Vinayak P. Dravid; C. N. R. Rao

Most of recent research on layered chalcogenides is understandably focused on single atomic layers. However, it is unclear if single-layer units are the most ideal structures for enhanced gas-solid interactions. To probe this issue further, we have prepared large-area MoS2 sheets ranging from single to multiple layers on 300 nm SiO2/Si substrates using the micromechanical exfoliation method. The thickness and layering of the sheets were identified by optical microscope, invoking recently reported specific optical color contrast, and further confirmed by AFM and Raman spectroscopy. The MoS2 transistors with different thicknesses were assessed for gas-sensing performances with exposure to NO2, NH3, and humidity in different conditions such as gate bias and light irradiation. The results show that, compared to the single-layer counterpart, transistors of few MoS2 layers exhibit excellent sensitivity, recovery, and ability to be manipulated by gate bias and green light. Further, our ab initio DFT calculations on single-layer and bilayer MoS2 show that the charge transfer is the reason for the decrease in resistance in the presence of applied field.


Advanced Materials | 2012

GaS and GaSe Ultrathin Layer Transistors

Dattatray J. Late; Bin Liu; Jiajun Luo; Aiming Yan; H. S. S. Ramakrishna Matte; M. Grayson; C. N. R. Rao; Vinayak P. Dravid

Room-temperature, bottom-gate, field-effect transistor characteristics of 2D ultrathin layer GaS and GaSe prepared from the bulk crystals using a micromechanical cleavage technique are reported. The transistors based on active GaS and GaSe ultrathin layers demonstrate typical n-and p-type conductance transistor operation along with a good ON/OFF ratio and electron differential mobility.


Journal of Applied Physics | 2013

Transient photoresponse in amorphous In-Ga-Zn-O thin films under stretched exponential analysis

Jiajun Luo; Alexander U. Adler; Thomas O. Mason; D. Bruce Buchholz; R. P. H. Chang; M. Grayson

We investigated transient photoresponse and Hall effect in amorphous In-Ga-Zn-O thin films and observed a stretched exponential response which allows characterization of the activation energy spectrum with only three fit parameters. Measurements of as-grown films and 350 K annealed films were conducted at room temperature by recording conductivity, carrier density, and mobility over day-long time scales, both under illumination and in the dark. Hall measurements verify approximately constant mobility, even as the photoinduced carrier density changes by orders of magnitude. The transient photoconductivity data fit well to a stretched exponential during both illumination and dark relaxation, but with slower response in the dark. The inverse Laplace transforms of these stretched exponentials yield the density of activation energies responsible for transient photoconductivity. An empirical equation is introduced, which determines the linewidth of the activation energy band from the stretched exponential param...


Review of Scientific Instruments | 2016

Modular time division multiplexer: Efficient simultaneous characterization of fast and slow transients in multiple samples

Stephan D. Kim; Jiajun Luo; D. Bruce Buchholz; R. P. H. Chang; M. Grayson

A modular time division multiplexer (MTDM) device is introduced to enable parallel measurement of multiple samples with both fast and slow decay transients spanning from millisecond to month-long time scales. This is achieved by dedicating a single high-speed measurement instrument for rapid data collection at the start of a transient, and by multiplexing a second low-speed measurement instrument for slow data collection of several samples in parallel for the later transients. The MTDM is a high-level design concept that can in principle measure an arbitrary number of samples, and the low cost implementation here allows up to 16 samples to be measured in parallel over several months, reducing the total ensemble measurement duration and equipment usage by as much as an order of magnitude without sacrificing fidelity. The MTDM was successfully demonstrated by simultaneously measuring the photoconductivity of three amorphous indium-gallium-zinc-oxide thin films with 20 ms data resolution for fast transients and an uninterrupted parallel run time of over 20 days. The MTDM has potential applications in many areas of research that manifest response times spanning many orders of magnitude, such as photovoltaics, rechargeable batteries, amorphous semiconductors such as silicon and amorphous indium-gallium-zinc-oxide.


15th International Conference on Narrow Gap Systems, NGS15 | 2011

Preparation of exfoliated Bi 2Te 3 thin films

Jiajun Luo; Dattatray J. Late; Isaac Wu; Kanishka Biswas; Mercouri G. Kanatzidis; M. Grayson

Bi2Te3, recently recognized as a “topological insulator”, is proposed to have enhanced electrical and thermoelectric properties due to the topological surface state. In this work, we describe our technique for synthesizing Bi2Te3 thin films with the Scotch tape method. We also describe strategies for fabricating samples for transport and thermoelectric measurements. Preliminary data of carrier density and mobility at room temperature was obtained.


15TH INTERNATIONAL CONFERENCE ON NARROW GAP SYSTEMS (NGS15) | 2011

Preparation of Exfoliated Bi[sub 2]Te[sub 3] Thin Films

Jiajun Luo; Dattatray J. Late; Isaac Wu; Kanishka Biswas; Mercouri G. Kanatzidis; M. Grayson; Giti Adham Khodaparast; Michael B. Santos; Christopher J. Stanton

Bi2Te3, recently recognized as a “topological insulator”, is proposed to have enhanced electrical and thermoelectric properties due to the topological surface state. In this work, we describe our technique for synthesizing Bi2Te3 thin films with the Scotch tape method. We also describe strategies for fabricating samples for transport and thermoelectric measurements. Preliminary data of carrier density and mobility at room temperature was obtained.


15TH INTERNATIONAL CONFERENCE ON NARROW GAP SYSTEMS (NGS15) | 2011

Preparation of Exfoliated Bi2Te3 Thin Films

Jiajun Luo; Dattatray J. Late; Isaac Wu; Kanishka Biswas; Mercouri G. Kanatzidis; M. Grayson

Bi2Te3, recently recognized as a “topological insulator”, is proposed to have enhanced electrical and thermoelectric properties due to the topological surface state. In this work, we describe our technique for synthesizing Bi2Te3 thin films with the Scotch tape method. We also describe strategies for fabricating samples for transport and thermoelectric measurements. Preliminary data of carrier density and mobility at room temperature was obtained.


Bulletin of the American Physical Society | 2017

Transient Hall Effect Measurement in Black Phosphorus

Jiajun Luo; Lintao Peng; Spencer A. Wells; Christopher R. Ryder; Mark C. Hersam; M. Grayson


Bulletin of the American Physical Society | 2017

Fourier-domain Mobility Spectrum Analysis (FMSA) for Characterizing Semiconductors with Multi-Electron/Hole Species

Boya Cui; Edward Kielb; Jiajun Luo; Yang Tang; M. Grayson


MRS Advances | 2016

Predictive and Descriptive Models for Transient Photoconductivity in Amorphous Oxide Semiconductors

Jiajun Luo; M. Grayson

Collaboration


Dive into the Jiajun Luo's collaboration.

Top Co-Authors

Avatar

M. Grayson

Northwestern University

View shared research outputs
Top Co-Authors

Avatar

Dattatray J. Late

Council of Scientific and Industrial Research

View shared research outputs
Top Co-Authors

Avatar

Isaac Wu

Northwestern University

View shared research outputs
Top Co-Authors

Avatar
Top Co-Authors

Avatar

Kanishka Biswas

Jawaharlal Nehru Centre for Advanced Scientific Research

View shared research outputs
Top Co-Authors

Avatar

Aiming Yan

Northwestern University

View shared research outputs
Top Co-Authors

Avatar

Bin Liu

Northwestern University

View shared research outputs
Top Co-Authors

Avatar
Top Co-Authors

Avatar
Top Co-Authors

Avatar
Researchain Logo
Decentralizing Knowledge