NAPAC2016 - List of Authors (Bell, G.I.)

Paper	Title	Page
THPOA41	Simulations of Hole Injection in Diamond Detectors	1184
	G.I. Bell, D.A. Dimitrov, C.D. Zhou Tech-X, Boulder, Colorado, USA I. Ben-Zvi, M. Gaowei, T. Rao, J. Smedley BNL, Upton, Long Island, New York, USA E.M. Muller SBU, Stony Brook, New York, USA
	Funding: This work is supported by the US DOE Office of Science, department of Basic Energy Sciences, under grant DE-SC0007577. We present simulations of a semiconductor beam detector using the code VSIM. The 3D simulations involve the movement and scattering of electrons and holes in the semiconductor, voltages which may be applied to external contacts, and self-consistent electrostatic fields inside the device. Electrons may experience a Schottky barrier when attempting to move from the semiconductor into a metal contact. The strong field near the contact, due to trapped electrons, can result in hole injection into the semiconductor due to transmission of electrons from the valence band of the semiconductor into the metal contact. Injected holes are transported in the applied field leading to current through the detector. We compare our simulation results with experimental results from a prototype diamond X-ray detector.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-NAPAC2016-THPOA41
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THPOA42	3D Modeling and Simulations of Electron Emission From Photocathodes With Controlled Rough Surfaces	1187
	D.A. Dimitrov, G.I. Bell, D.N. Smithe, C.D. Zhou Tech-X, Boulder, Colorado, USA I. Ben-Zvi, J. Smedley BNL, Upton, Long Island, New York, USA S.S. Karkare, H.A. Padmore LBNL, Berkeley, California, USA
	Funding: This work is supported by the US DOE Office of Science, department of Basic Energy Sciences under grant DE-SC0013190. Developments in materials design and synthesis have resulted in photocathodes that can have a high quantum efficiency (QE), operate at visible wavelengths, and are robust enough to operate in high electric field gradient photoguns, for application to free electron lasers and in dynamic electron microscopy and diffraction. However, synthesis often results in roughness, ranging from the nano to the microscale. The effect of this roughness in a high gradient accelerator is to produce a small transverse accelerating gradient, which therefore results in emittance growth. Although analytical formulations of the effects of roughness have been developed, a full theoretical model and experimental verification are lacking, and our work aims to bridge this gap. We report results on electron emission modeling and 3D simulations from photocathodes with controlled surface roughness similar to grated surfaces that have been fabricated by nanolithography. The simulations include both charge carrier dynamics in the photocathode material and a general electron emission modeling that includes field enhancement effects at rough surfaces. The models are being implemented in the VSim code.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-NAPAC2016-THPOA42
Export •	reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

Paper

Title

Page

Simulations of Hole Injection in Diamond Detectors

1184

G.I. Bell, D.A. Dimitrov, C.D. Zhou
Tech-X, Boulder, Colorado, USA
I. Ben-Zvi, M. Gaowei, T. Rao, J. Smedley
BNL, Upton, Long Island, New York, USA
E.M. Muller
SBU, Stony Brook, New York, USA

Funding: This work is supported by the US DOE Office of Science, department of Basic Energy Sciences, under grant DE-SC0007577.
We present simulations of a semiconductor beam detector using the code VSIM. The 3D simulations involve the movement and scattering of electrons and holes in the semiconductor, voltages which may be applied to external contacts, and self-consistent electrostatic fields inside the device. Electrons may experience a Schottky barrier when attempting to move from the semiconductor into a metal contact. The strong field near the contact, due to trapped electrons, can result in hole injection into the semiconductor due to transmission of electrons from the valence band of the semiconductor into the metal contact. Injected holes are transported in the applied field leading to current through the detector. We compare our simulation results with experimental results from a prototype diamond X-ray detector.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-NAPAC2016-THPOA41

Export •

reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

THPOA42

3D Modeling and Simulations of Electron Emission From Photocathodes With Controlled Rough Surfaces

1187

D.A. Dimitrov, G.I. Bell, D.N. Smithe, C.D. Zhou
Tech-X, Boulder, Colorado, USA
I. Ben-Zvi, J. Smedley
BNL, Upton, Long Island, New York, USA
S.S. Karkare, H.A. Padmore
LBNL, Berkeley, California, USA

Funding: This work is supported by the US DOE Office of Science, department of Basic Energy Sciences under grant DE-SC0013190.
Developments in materials design and synthesis have resulted in photocathodes that can have a high quantum efficiency (QE), operate at visible wavelengths, and are robust enough to operate in high electric field gradient photoguns, for application to free electron lasers and in dynamic electron microscopy and diffraction. However, synthesis often results in roughness, ranging from the nano to the microscale. The effect of this roughness in a high gradient accelerator is to produce a small transverse accelerating gradient, which therefore results in emittance growth. Although analytical formulations of the effects of roughness have been developed, a full theoretical model and experimental verification are lacking, and our work aims to bridge this gap. We report results on electron emission modeling and 3D simulations from photocathodes with controlled surface roughness similar to grated surfaces that have been fabricated by nanolithography. The simulations include both charge carrier dynamics in the photocathode material and a general electron emission modeling that includes field enhancement effects at rough surfaces. The models are being implemented in the VSim code.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-NAPAC2016-THPOA42

Export •

reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)