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Search Publications by: Nhan Van Nguyen (Assoc)

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Displaying 26 - 50 of 96

Electronic Structure and Band Alignment at Epitaxial Co3O4/SrTiO3 Heterojunction

July 21, 2014
Author(s)
Liang Qiao, Wei Li, Haiyan xiao, Harry M. Meyer, Xuelei Liang, Nhan Van Nguyen, Michael D. Biegalski
The electronic properties of solid-solid interfaces play critical roles in a variety of technological applications. Recent advance of film epitaxy and characterization techniques have demonstrated a wealthy of exotic phenomena at interfaces of oxide

Time-resolved surface infrared spectroscopy during atomic layer deposition of TiO2 using tetrakis(dimethylamido)titanium and water

April 23, 2014
Author(s)
Brent A. Sperling, John Hoang, William A. Kimes, James E. Maslar, Kristen L. Steffens, Nhan V. Nguyen
Atomic layer deposition of titanium dioxide using tetrakis(dimethylamido)titanium (TDMAT) and water vapor is studied by reflection-absorption infrared spectroscopy (RAIRS) with a time resolution of 120 ms. Decomposition of the adsorbed TDMAT is observed

Graphene as Transparent Electrode for Direct Observation of Hole Photoemission from Silicon to Oxide

March 27, 2013
Author(s)
Rusen Yan, Qin Zhang, Oleg A. Kirillov, Wei Li, James I. Basham, Alexander G. Boosalis, Xuelei X. Liang, Debdeep Jena, Curt A. Richter, Alan C. Seabaugh, David J. Gundlach, Huili G. Xing, Nhan V. Nguyen
The outstanding electrical and optical properties of graphene make it an excellent alternative as a transparent electrode. Here we demonstrate the application of graphene as collector material in internal photoemission (IPE) spectroscopy; enabling the

Backcontact CdSe/CdTE Windowless Solar Cells

February 1, 2013
Author(s)
Donguk Kim, Carlos M. Hangarter, Ratan K. Debnath, Jong Y. Ha, Carlos R. Beauchamp, Matthew D. Widstrom, Jonathan E. Guyer, Nhan Van Nguyen, B. Y. Yoo, Daniel Josell
This paper details the fabrication and properties of CdSe/CdTe thin film photovoltaic devices with a dual back contact geometry. Device fabrication involves cadmium selenide electrodeposition on one of two interdigitated electrodes on a pre-patterned

Band Offset Determination of Atomic-Layer-Deposited Al2O3 and HfO2 on InP by Internal Photoemission and Spectroscopic Ellipsometry

January 9, 2013
Author(s)
Kun Xu, Oleg A. Kirillov, David J. Gundlach, Nhan V. Nguyen, Pei D. Ye, Min Xu, Lin Dong, Hong Sio
Band offsets at the interfaces of n- and p-type InP ((100) and (111)A) and atomic-layer-deposited (ALD) Al2O3 were measured with internal photoemission and spectroscopic ellipsometry. Similarly, the band offsets at the interface of semi-insulating InP (100

A Unique Photoemission Method to Measure Semiconductor Heterojunction Band Offsets

January 2, 2013
Author(s)
Qin Zhang, Rui Li, Rusen Yan, Thomas Kosel, Grace Xing, Alan Seabaugh, Kun Xu, Oleg A. Kirillov, David J. Gundlach, Curt A. Richter, Nhan V. Nguyen
We report a unique way to measure the energy band offset of a heterojunction by exploiting the light absorption profile in the heterojunction under visible-ultraviolet internal photoemission. This method was used to successfully determine the band

Direct Measurement of Intrinsic Dirac Point and Fermi level at Graphene/Oxide interface and Its Band Alignment by Cavity Enhanced Internal Photoemission

December 17, 2012
Author(s)
Kun Xu, Caifu Zeng, Qin Zhang, Rusen Yan, Peide Ye, Kang Wang, Alan C. Seabaugh, Huili G. Xing, John S. Suehle, Curt A. Richter, David J. Gundlach, Nhan V. Nguyen
We report the first direct measurement of the Dirac point, the Fermi level, and the work function of graphene by performing internal photoemission measurements on a graphene/SiO2/Si structure with a unique optical-cavity enhanced test structure. A complete

Determination of graphene work function and graphene-insulator-semiconductor band alignment by internal photoemission spectroscopy

July 11, 2012
Author(s)
Rusen Yan, Qin Zhang, Wei Li, Irene G. Calizo, Tian T. Shen, Curt A. Richter, Angela R. Hight Walker, Xuelei X. Liang, David J. Gundlach, Nhan Van Nguyen, Huili G. Xing, Alan Seabaugh
We determined the band alignment of a graphene-oxide-silicon structure using internal photoemission spectroscopy. From the flatband voltage and Dirac voltage we infer a 4.3 10e11 cm-2 negative extrinsic charge present on the graphene surface. Also, we

Tunnel FET Heterojunction Band Alignment by Internal Photoemission Spectroscopy

March 6, 2012
Author(s)
Qin Zhang, Guangle Zhou, Huili G. Xing, Alan C. Seabaugh, Kun Xu, Sio Hong, Oleg A. Kirillov, Curt A. Richter, Nhan Van Nguyen
The electron energy band alignment of a metal-oxide-semiconductor tunnel field-effect transistor (TFET) heterojunction, W/Al2O3/InGaAs/InAs/InP is determined by internal photoemission spectroscopy. At the oxide flat-band condition, the barrier height from

Photoemission Threshold Spectroscopy: MOS Band alignments

April 7, 2011
Author(s)
Nhan V. Nguyen
In this talk I will 1) briefly review SED’s history of the optical thin metrology project, 2) describe the principle of internal photoemission (IPE) and the applications to determine the band alignments of metal-oxide-semiconductor structures, and 3)

Band offsets of atomic-layer-deposited Al2O3 on GaAs and the effects of surface treatment.

August 27, 2008
Author(s)
Nhan V. Nguyen, Oleg A. Kirillov, Weirong Jiang, Wenyong Wang, John S. Suehle, P. D. Ye, Y. Xuan, N. Goel, Kwang-Woo Choi, Wilman Tsai
In this letter we report the band offsets of the Al/Al2O3/GaAs structure determined by internal photoemission and spectroscopic ellipsometry. The energy barrier height at the Al2O3 and sulfur-passivated GaAs interface is found to be 3.0 eV, which is

The relationship between local order, long range order, and sub-bandgap defects in hafnium oxide and hafnium silicate films

May 9, 2008
Author(s)
D. H. Hill, Robert A. Bartynski, Nhan Van Nguyen, Albert Davydov, Deane Chandler-Horowitz, Martin M. Frank
We have measured X-ray absorption spectra (XAS) at the oxygen K-edge for hafnium oxide (HfO2) films grown by chemical vapor deposition (CVD) and atomic layer deposition (ALD), as well as hafnium silicate (HfSiO) films grown by CVD.  The XAS results are

Internal Photoemission Spectroscopy of [TaN/TaSiN] and [TaN/TaCN] Metal Stacks On SiO2 and [HfO2 / SiO2] Dielectric Stack.

March 6, 2008
Author(s)
Nhan V. Nguyen, Hao Xiong, John S. Suehle, Oleg A. Kirillov, Eric Vogel, Prashant Majhi, Huang-Chun Wen
Metal gates have been intensively searched to replace the poly-silicon for the next generation metal-oxide-semiconductor field-effect transistor. The barrier height (??0) at their interfaces with a gate dielectric must be known to select a suitable metal

High Sensitivity FTIR-ATR Study of Ultra-Thin Zr02 Films: A Study of Phase Change

February 12, 2008
Author(s)
Safak Sayan, Deane Chandler-Horowitz, Nhan Van Nguyen, James R. Ehrstein, Mark Croft
Fourier Transform Infrared spectroscopy (FTIR) using the Attenuated Total Reflection (ATR) method was performed in the mid-IR spectral region on ultrathin ZrO2 films deposited on silicon wafers. A vibrational mode near 710 cm-1 was observed that undergoes