Lanxia Cheng

Lanxia Cheng is currently working as a research scientist in the department of Materials Science and Engineering at the University of Texas at Dallas under the direction of Prof. Jiyoung Kim. She obtained her Ph.D degree in the major of surface chemistry from St Andrews University, Scotland under the supervision of Prof. Neville Richardson. Her Ph.D research topic focuses on the fundamental understanding of organic molecular adsorption behaviors at a single crystal metal surface under UHV environment by means of surface sentivitive techniques such as scanning tunneling microscopy (STM), RAIRS, EELS, XPS etc. Since joining in UTD 2012, her areas of research interests have been extended to the growth, characterization and device integration of 2D semiconductor materials including graphene/graphite, transition metal dichalcogenides(TMDs) towards future nanoelectronics applications. A detailed information regarding her research interests and publications can be found at [Link to Research Gate]

Growth and characterization, surface and interface engineerings of graphene and TMDs are of scientific importance for realizatizing 2D based high performance nanoelectronics such as BiSFETs and ITFETs. Under this project sponsored by SWAN-SRC and Texas Instruments, a great of her research efforts have been dedicated to address the following challenges: (1) Controllable low temperature growth of graphite. (2) Scalable thin dielectric growth on graphene and MoS2; (3) Wafer-scale Graphene based devcies integration. Under the first task, her work has demonstrated high quality vertically stacked graphite films grown at a temperature as low as 400 °C by employing the plasma enhanced chemical deposition, which presents a promising way of integrating this nanostructured graphite directly into device process as pontential replacement of Cu inconnects[JMCC, 3, 2015, pp5129]. Under the second task, several different thin deposition techniques have been explored and investigated to grow a wide range of interesting thin dielectric films, such as Physcial vapor deposition (PVD) of self-assembled organic dielectric film (PTCDA), Atomic Layer deposition (ALD) of inorganic dielectrics (Al2O3, SiO2), and Molecular Atomic Layer deposition (MALD) of hybrid dielectrics (OTS/TMA or TiCl4) on graphene and MoS2. With assistance of proper interfacial chemical engineeings through surface funalizations, high quality scalable inorganic or hybrid dielectrics down to a few nanometers have been demonstrated with excellent preservation of the structural, chemical and electrical properties of underlying 2D semiconductor[ACS Appl. mater. Interfaces, 2014, 6, pp11834] Within the third task, the undergoing efforts is devolted to develop an optimized device integration process for fabrication of high performance wafer-scale graphene based devices.

Her main characterization tools are AFM and Raman that are very powerful for studying the structural, chemical and electronic properties of 2D semicondcutors, in

particular graphene and TMDs including MoS2, WSe2, MoSe2 … etc. This pictures show the advanced Reinshaw confocal Raman spectrometer coupled with a ND-MDT NTEGRA Atomic Force Microscopy (AFM) located in our lab. The Raman is equipped with two wavelength lasers (532 nm and 442 nm) and is capable of not only high resolution (0.5 cm-1) spectra acquisition but also high spatial resolution (~300 nm) fast Raman mapping from several micro meters to wafer scale. By cominating of Raman with AFM tip, a simtaneous tip enhanced Raman mapping and AFM imaging allows for a detailed investigation of the relationship between a local surface structural, electronic properties and surface morphology. Additionlly, this Raman is also equipped with a in-situ heating and cooling stage that enables a Raman monintoring of structural changes under wide temperature window between ~196 – to 600 °C under a N2 purge inert environment[ACS Appl. Mater. Interfaces, 2016, 8 (7), pp 5002–5008]