Title: Extreme Carrier Depletion and Superlinear Photoconductivity in Ultrathin Parallel-Aligned ZnO Nanowire Array Photodetectors Fabricated by Infiltration Synthesis

Abstract

Abstract Ultrathin semiconductor nanowires enable high‐performance chemical sensors and photodetectors, but their synthesis and device integration by standard complementary metal‐oxide‐semiconductor (CMOS)‐compatible processes remain persistent challenges. This work demonstrates fully CMOS‐compatible synthesis and integration of parallel‐aligned polycrystalline ZnO nanowire arrays into ultraviolet photodetectors via infiltration synthesis, material hybridization technique derived from atomic layer deposition. The nanowire photodetector features unique, high device performances originating from extreme charge carrier depletion, achieving photoconductive on–off ratios of >6 decades, blindness to visible light, and ultralow dark currents as low as 1 fA, the lowest reported for nanostructure‐based photoconductive photodetectors. Surprisingly, the low dark current is invariant with increasing number of nanowires and the photodetector shows unusual superlinear photoconductivity, observed for the first time in nanowires, leading to increasing detector responsivity and other parameters for higher incident light powers. Temperature‐dependent carrier concentration and mobility reveal the photoelectrochemical‐thermionic emission process at grain boundaries, responsible for the observed unique photodetector performances and superlinear photoconductivity. The results elucidate fundamental processes responsible for photogain in polycrystalline nanostructures, providing useful guidelines for developing nanostructure‐based detectors and sensors. The developed fully CMOS‐compatible nanowire synthesis and device fabrication methods also have potentials for scalable integration of nanowire sensor devices and circuitries.

Authors:

Nam, Chang-Yong  ^[1];

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• Search DOE PAGES for ORCID "0000-0002-9093-4063"

Stein, Aaron ^[1]

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+ Show Author Affiliations

1. Brookhaven National Lab. (BNL), Upton, NY (United States). Center for Functional Nanomaterials (CFN)

Publication Date:

Wed Nov 15 00:00:00 EST 2017

Research Org.:

Brookhaven National Laboratory (BNL), Upton, NY (United States)

Sponsoring Org.:

USDOE Office of Science (SC), Basic Energy Sciences (BES)

OSTI Identifier:

1426786

Alternate Identifier(s):

OSTI ID: 1409471

Report Number(s):

BNL-114849-2017-JAAM
Journal ID: ISSN 2195-1071

Grant/Contract Number:  

SC0012704; DE‐SC0012704

Resource Type:

Accepted Manuscript

Journal Name:

Advanced Optical Materials

Additional Journal Information:

Journal Volume: 5; Journal Issue: 24; Journal ID: ISSN 2195-1071

Publisher:

Wiley

Country of Publication:

United States

Language:

English

Subject:

36 MATERIALS SCIENCE; infiltration synthesis; ZnO nanowire; photodetector; thermionic emission; ultralow dark current