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Search Publications by: David Gundlach (Fed)

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Displaying 26 - 50 of 180

Calibration and impact of bulk trap-assisted tunneling and Shockley-Read-Hall currents in InGaAs tunnel-FETs

September 1, 2017
Author(s)
Quentin Smets, Anne S. Verhulst, Eddy Simoen, David J. Gundlach, Curt A. Richter, Nadine Collaert, Marc Heyns
The tunnel-FET (TFET) is a promising candidate for future low-power logic applications because it enables a sub-60 mV/dec subthreshold swing. However, most experimental TFETs are plagued by unwanted trap-assisted tunneling (TAT) and Shockley-Read-Hall (SRH

The dependence of electrical performance on structural organization in low mobility polymer field effect transistors

April 16, 2017
Author(s)
Emily G. Bittle, Hyun W. Ro, Chad R. Snyder, Sebastian Engmann, Regis J. Kline, Oana Jurchescu, Dean M. DeLongchamp, David J. Gundlach
Polymer semiconductors are contenders for use in printed, flexible electronics. Though organic electronic materials have been studied for many years, the physics of charge transport is still under investigation. This is in part due to the large variability

Cryogenic pulsed I-V measurements on homo- and heterojunction III-V TFETs

April 1, 2017
Author(s)
Quentin Smets, Jihong Kim, Jason Campbell, David M. Nminibapiel, Dmitry Veksler, Pragya Shrestha, Rahul Pandey, Anne S. Verhulst, Eddy Simoens, David J. Gundlach, Curt A. Richter, Kin P. Cheung, Suman Suman, Anda Mocuta, Nadine Collaert, Aaron Thean, Marc Heyns
Most experimental reports of tunneling field-effect transistors show defect-related performance degradation. Charging of oxide traps causes Fermi level pinning, and Shockley-Read-Hall (SRH)/trap-assisted tunneling (TAT) generation cause unwanted leakage

Reduced Bimolecular Recombination in Blade-Coated, High-Efficiency, Small-Molecule Solar Cells

March 22, 2017
Author(s)
Sebastian Engmann, Hyun W. Ro, Andrew A. Herzing, Dean M. DeLongchamp, Chad R. Snyder, Lee J. Richter, Adam J. Barito, David J. Gundlach
The full benefit of emerging solution deposited photovoltaic devices requires development of processes compatible with high speed manufacturing. Extensive studies of the lab-to-fab challenge have been performed on polymer donor based organic photovoltaics

Calibration of Effective Tunneling Bandgap in GaAsSb/InGaAs for improved TFET Performance Prediction

November 3, 2016
Author(s)
Quentin Smets, Anne S. Verhulst, Salim El Kazzi, David J. Gundlach, Curt A. Richter, Anda Mocuta, Nadine Collaert, Aaron Thean, Marc Heyns
The effective bandgap for heterojunction band-to-band tunneling (Eg,eff) is a crucial design parameter for heterojunction TFET. However, there is significant uncertainty on Eg,eff, especially for In0.53Ga0.47As/GaAs0.5Sb0.5. This makes TFET performance

Observation of Strong Reflection of Electron Waves Exiting a Ballistic Channel at Low Energy

June 10, 2016
Author(s)
Jason Campbell, Jason Ryan, Kin P. Cheung, David J. Gundlach, Changze Liu, Canute I. Vaz, Richard G. Southwick III, Anthony S. Oates, Ru Huang
Wave scattering by a potential step is a nearly ubiquitous concept. Thus, it is surprising that theoretical treatments of ballistic transport in nanoscale devices, from quantum point contacts to ballistic transistors, assume no reflection even when the

Mobility overestimation due to gated contacts in organic field-effect transistors

March 10, 2016
Author(s)
Emily G. Bittle, David J. Gundlach, Oana Jurchescu, James I. Basham, Thomas Jackson
Parameters used to describe the electrical properties of organic field-effect transistors, such as mobility and threshold voltage, are commonly extracted from measured current–voltage characteristics and interpreted by using the classical metal oxide

Broadband Optical Properties of Graphene by Spectroscopic Ellipsometry

December 11, 2015
Author(s)
Wei Li, Nhan Van Nguyen, Guangjun Cheng, Angela R. Hight Walker, David J. Gundlach, Yiran Liang, boyuan Tian, Xuelei Liang, Lian-Mao Peng
The broadband (0.7 eV to 9.0 eV) optical properties of chemical-vapor-deposition (CVD) grown graphene are determined by spectroscopic ellipsometry. The optical absorption follows the fine structure constant in the energy range from 1.0 eV to 2.0 eV, but

Influence of Metal?MoS2 Interface on MoS2 Transistor Performance: Comparison of Ag and Ti Contacts

December 16, 2014
Author(s)
Hui H. Yuan, Guangjun Cheng, Lin You, Haitao Li, Hao Zhu, Wei Li, Joseph J. Kopanski, Yaw S. Obeng, Angela R. Hight Walker, David J. Gundlach, Curt A. Richter, D. E. Ioannou, Qiliang Li
In this work, we present a study of enhancing MoS2 transistor performance by using proper metal contact. We found that the on-state current of MoS2 field-effect transistors with 30 nm Au/ 30 nm Ag contacts is enhanced more than 60 times and the