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Title: Microwave Frequency Comb from a Semiconductor in a Scanning Tunneling Microscope

Abstract

Abstract Quasi-periodic excitation of the tunneling junction in a scanning tunneling microscope, by a mode-locked ultrafast laser, superimposes a regular sequence of 15 fs pulses on the DC tunneling current. In the frequency domain, this is a frequency comb with harmonics at integer multiples of the laser pulse repetition frequency. With a gold sample the 200th harmonic at 14.85 GHz has a signal-to-noise ratio of 25 dB, and the power at each harmonic varies inversely with the square of the frequency. Now we report the first measurements with a semiconductor where the laser photon energy must be less than the bandgap energy of the semiconductor; the microwave frequency comb must be measured within 200μm of the tunneling junction; and the microwave power is 25 dB below that with a metal sample and falls off more rapidly at the higher harmonics. Our results suggest that the measured attenuation of the microwave harmonics is sensitive to the semiconductor spreading resistance within 1 nm of the tunneling junction. This approach may enable sub-nanometer carrier profiling of semiconductors without requiring the diamond nanoprobes in scanning spreading resistance microscopy.

Authors:
; ;
Publication Date:
Research Org.:
Los Alamos National Lab. (LANL), Los Alamos, NM (United States)
Sponsoring Org.:
USDOE Office of Science (SC). Basic Energy Sciences (BES) (SC-22)
OSTI Identifier:
1483526
Report Number(s):
LA-UR-18-23275
Journal ID: ISSN 1431-9276; applab
DOE Contract Number:  
89233218CNA000001
Resource Type:
Journal Article
Resource Relation:
Journal Name: Microscopy and Microanalysis; Journal Volume: 23; Journal Issue: 02
Country of Publication:
United States
Language:
English
Subject:
Material Science

Citation Formats

Hagmann, Mark J., Yarotski, Dmitry A., and Mousa, Marwan S.. Microwave Frequency Comb from a Semiconductor in a Scanning Tunneling Microscope. United States: N. p., 2016. Web. doi:10.1017/S1431927616012563.
Hagmann, Mark J., Yarotski, Dmitry A., & Mousa, Marwan S.. Microwave Frequency Comb from a Semiconductor in a Scanning Tunneling Microscope. United States. doi:10.1017/S1431927616012563.
Hagmann, Mark J., Yarotski, Dmitry A., and Mousa, Marwan S.. Tue . "Microwave Frequency Comb from a Semiconductor in a Scanning Tunneling Microscope". United States. doi:10.1017/S1431927616012563.
@article{osti_1483526,
title = {Microwave Frequency Comb from a Semiconductor in a Scanning Tunneling Microscope},
author = {Hagmann, Mark J. and Yarotski, Dmitry A. and Mousa, Marwan S.},
abstractNote = {Abstract Quasi-periodic excitation of the tunneling junction in a scanning tunneling microscope, by a mode-locked ultrafast laser, superimposes a regular sequence of 15 fs pulses on the DC tunneling current. In the frequency domain, this is a frequency comb with harmonics at integer multiples of the laser pulse repetition frequency. With a gold sample the 200th harmonic at 14.85 GHz has a signal-to-noise ratio of 25 dB, and the power at each harmonic varies inversely with the square of the frequency. Now we report the first measurements with a semiconductor where the laser photon energy must be less than the bandgap energy of the semiconductor; the microwave frequency comb must be measured within 200μm of the tunneling junction; and the microwave power is 25 dB below that with a metal sample and falls off more rapidly at the higher harmonics. Our results suggest that the measured attenuation of the microwave harmonics is sensitive to the semiconductor spreading resistance within 1 nm of the tunneling junction. This approach may enable sub-nanometer carrier profiling of semiconductors without requiring the diamond nanoprobes in scanning spreading resistance microscopy.},
doi = {10.1017/S1431927616012563},
journal = {Microscopy and Microanalysis},
number = 02,
volume = 23,
place = {United States},
year = {Tue Dec 20 00:00:00 EST 2016},
month = {Tue Dec 20 00:00:00 EST 2016}
}