Simultaneous thermoelectric and optoelectronic characterization of individual nanowires

Journal Article · Tue Nov 03 00:00:00 EST 2015 · Nano Letters

DOI:https://doi.org/10.1021/acs.nanolett.5b03572· OSTI ID:1237702

Leonard, Francois ^[1]; Wang, George T. ^[2]; Swartzentruber, Brian S. ^[2]; Martinez, Julio A. ^[3]; Song, Erdong ^[3]; Li, Qiming ^[2]

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1. Sandia National Lab. (SNL-CA), Livermore, CA (United States)
2. Sandia National Lab. (SNL-NM), Albuquerque, NM (United States)
3. New Mexico State Univ., Las Cruces, NM (United States)

Semiconducting nanowires have been explored for a number of applications in optoelectronics such as photodetectors and solar cells. Currently, there is ample interest in identifying the mechanisms that lead to photoresponse in nanowires in order to improve and optimize performance. However, distinguishing among the different mechanisms, including photovoltaic, photothermoelectric, photoemission, bolometric, and photoconductive, is often difficult using purely optoelectronic measurements. In this work, we present an approach for performing combined and simultaneous thermoelectric and optoelectronic measurements on the same individual nanowire. We apply the approach to GaN/AlGaN core/shell and GaN/AlGaN/GaN core/shell/shell nanowires and demonstrate the photothermoelectric nature of the photocurrent observed at the electrical contacts at zero bias, for above- and below-bandgap illumination. Furthermore, the approach allows for the experimental determination of the temperature rise due to laser illumination, which is often obtained indirectly through modeling. We also show that under bias, both above- and below-bandgap illumination leads to a photoresponse in the channel with signatures of persistent photoconductivity due to photogating. Finally, we reveal the concomitant presence of photothermoelectric and photogating phenomena at the contacts in scanning photocurrent microscopy under bias by using their different temporal response. Furthermore, our approach is applicable to a broad range of nanomaterials to elucidate their fundamental optoelectronic and thermoelectric properties.

• Research Organization: Sandia National Lab. (SNL-CA), Livermore, CA (United States); Sandia National Lab. (SNL-NM), Albuquerque, NM (United States)
• Sponsoring Organization: USDOE Office of Science (SC), Basic Energy Sciences (BES)
• Grant/Contract Number: AC04-94AL85000
• OSTI ID: 1237702
• Report Number(s): SAND-2015-7507J; 603460
• Journal Information: Nano Letters, Vol. 15, Issue 12; ISSN 1530-6984
• Publisher: American Chemical Society
• Country of Publication: United States
• Language: English

Related Subjects

77 NANOSCIENCE AND NANOTECHNOLOGY
nanowires
GaN
GaN/AlGaN
photocurrent
thermoelectric
photogating