Title: Measuring the Surface Photovoltage of a Schottky Barrier under Intense Light Conditions: Zn/p-Si(100) by Laser Time-Resolved Extreme Ultraviolet Photoelectron Spectroscopy

Abstract

A metal-semiconductor heterojunction is investigated by Auger and photoelectron spectroscopy to characterize the structural and electronic properties of the metallic film and to obtain the time-resolved electronic response induced by femtosecond laser excitation of the semiconductor material. The 3.5 monolayer (ML) Zn films deposited on p-type Si(100) at liquid nitrogen temperature grows in a layer-by-layer fashion. Electronic structure measurements by extreme ultraviolet (XUV) photoelectron spectroscopy indicate that the films are metallic in nature, creating a Schottky barrier at the 3.5 ML Zn/p-Si(100) interface. Utilizing a 35 fs, 800 nm pump pulse at a pump intensity of (2.5-6) × 10 ⁹ W/cm ² to excite the Si and a time-delayed extreme ultraviolet pulse to probe the Zn, we observed large transient surface photovoltage shifts of 0.3-2.2 eV at carrier densities of (1.5-4.5) × 10 ²⁰ cm ^-3. Three shifts are determined the Zn 3d core level, the photoemission onset, and the metallic Fermi level. The photovoltages increase with laser excitation intensity, and the Zn 3d core level exhibits the largest binding energy shifts due to pronounced screening of the core level. The large observed shifts are rationalized on the basis of the energetics of band flattening and carrier accumulation in themore » metallic layer of the Zn/p-Si(100) heterojunction at high carrier densities. The observed carrier recombination dynamics are biexponential in character, with similar time constants for both the Zn 3d and photoemission onset binding energy shifts. The Zn 3d core level shifts are also found to be sensitive to the electron temperature. These results show that core-level photoemission can be used to monitor valence electron dynamics, allowing separation of charge dynamics in heterojunctions and solids composed of multiple elements.« less

Authors:

Marsh, Brett M.  ^[1];

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Vaida, Mihai E. ^[2]; Cushing, Scott K. ^[3]; Lamoureux, Bethany R. ^[3]; Leone, Stephen R.  ^[3]

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+ Show Author Affiliations

1. Univ. of California, Berkeley, CA (United States)
2. Univ. of Central Florida, Orlando, FL (United States). Dept. of Chemistry and Department of Physics
3. Univ. of California, Berkeley, CA (United States); Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States)

Publication Date:

2017-09-29

Research Org.:

Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States)

Sponsoring Org.:

USDOE Office of Science (SC); USDOE Office of Energy Efficiency and Renewable Energy (EERE)

OSTI Identifier:

1532264

Grant/Contract Number:  

AC02-05CH11231

Resource Type:

Journal Article: Accepted Manuscript

Journal Name:

Journal of Physical Chemistry. C

Additional Journal Information:

Journal Volume: 121; Journal Issue: 40; Journal ID: ISSN 1932-7447

Publisher:

American Chemical Society

Country of Publication:

United States

Language:

English

Subject:

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY