Abstract

Autonomous smart windows may be integrated with a stack of active components, such as electrochromic devices, to modulate the opacity/transparency by an applied voltage. This voltage may be generated with a visibly transparent photovoltaic device. This paper describes the processing and performance of zinc oxide (ZnO) films for integration with electrochromic stacks. Sputtered ZnO (2% Mn) films on indium-tin oxide with transparency in the visible range were used to fabricate metal-semiconductor (MS), metal-insulator-semiconductor, and p-i-n heterojunction devices, and their photovoltaic conversion under ultraviolet (UV) illumination was evaluated with and without oxygen plasma-treated surface electrodes (Au, Ag, Al, and Ti/Ag). The MS Schottky parameters were fit against the generalized Bardeen model to obtain the density of interface states (Dit ≈ 8.0x10¹¹ eV⁻¹cm⁻²) and neutral level (Eo ≈ -5.2 eV). These devices have exhibited a photoconductive behavior at λ = 365 nm, and low-noise Ag-ZnO detectors have exhibited the responsivity (R) and photoconductive gain (G) of 1.93x10⁻⁴ A/W and 6.57x10⁻⁴, respectively. Confirmed via matched-pair analysis, postmetallization oxygen plasma treatment of Ag and Ti/Ag electrodes has resulted in increased Schottky barrier heights, which maximized with a 2-nm SiO₂ electron blocking layer, coupled with the suppression of recombination at the MS interface and blocking of majority carriers. For interdigitated devices under monochromatic UV-C illumination, the open-circuit voltage (Voc) was 1.2 V and short-circuit current density (Jsc), due to minority carrier tunneling, was 0.68 mA/cm².

Original languageEnglish (US)
JournalIEEE Transactions on Electron Devices
DOIs
StateAccepted/In press - Jul 1 2018

Fingerprint

Zinc Oxide
Zinc oxide
Oxides
Multilayers
Metals
Semiconductor materials
Transparency
Lighting
Oxygen
Electrochromic devices
Plasmas
Electrodes
Interface states
Opacity
Electric potential
Open circuit voltage
Tin oxides
Short circuit currents
Indium
Oxide films

Keywords

  • II-VI semiconductor materials
  • Lighting
  • Manganese
  • Photovoltaic cells
  • photovoltaic detectors
  • Photovoltaic systems
  • Schottky barriers
  • Schottky barriers
  • semiconductor-insulator interfaces
  • semiconductor-metal interfaces
  • ultraviolet (UV) detectors.
  • Zinc oxide

ASJC Scopus subject areas

  • Electronic, Optical and Magnetic Materials
  • Electrical and Electronic Engineering

Cite this

ZnO-Based Schottky and Oxide Multilayer Devices for Visibly Transparent Photovoltaic Applications. / Azhar, Ebraheem Ali; Ye, Weidong; Helfrecht, Benjamin; Chen, George; Thompson, Lucas; Yu, Hongbin; Dey, Sandwip.

In: IEEE Transactions on Electron Devices, 01.07.2018.

Research output: Contribution to journalArticle

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abstract = "Autonomous smart windows may be integrated with a stack of active components, such as electrochromic devices, to modulate the opacity/transparency by an applied voltage. This voltage may be generated with a visibly transparent photovoltaic device. This paper describes the processing and performance of zinc oxide (ZnO) films for integration with electrochromic stacks. Sputtered ZnO (2{\%} Mn) films on indium-tin oxide with transparency in the visible range were used to fabricate metal-semiconductor (MS), metal-insulator-semiconductor, and p-i-n heterojunction devices, and their photovoltaic conversion under ultraviolet (UV) illumination was evaluated with and without oxygen plasma-treated surface electrodes (Au, Ag, Al, and Ti/Ag). The MS Schottky parameters were fit against the generalized Bardeen model to obtain the density of interface states (Dit ≈ 8.0x10¹¹ eV⁻¹cm⁻²) and neutral level (Eo ≈ -5.2 eV). These devices have exhibited a photoconductive behavior at λ = 365 nm, and low-noise Ag-ZnO detectors have exhibited the responsivity (R) and photoconductive gain (G) of 1.93x10⁻⁴ A/W and 6.57x10⁻⁴, respectively. Confirmed via matched-pair analysis, postmetallization oxygen plasma treatment of Ag and Ti/Ag electrodes has resulted in increased Schottky barrier heights, which maximized with a 2-nm SiO₂ electron blocking layer, coupled with the suppression of recombination at the MS interface and blocking of majority carriers. For interdigitated devices under monochromatic UV-C illumination, the open-circuit voltage (Voc) was 1.2 V and short-circuit current density (Jsc), due to minority carrier tunneling, was 0.68 mA/cm².",
keywords = "II-VI semiconductor materials, Lighting, Manganese, Photovoltaic cells, photovoltaic detectors, Photovoltaic systems, Schottky barriers, Schottky barriers, semiconductor-insulator interfaces, semiconductor-metal interfaces, ultraviolet (UV) detectors., Zinc oxide",
author = "Azhar, {Ebraheem Ali} and Weidong Ye and Benjamin Helfrecht and George Chen and Lucas Thompson and Hongbin Yu and Sandwip Dey",
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T1 - ZnO-Based Schottky and Oxide Multilayer Devices for Visibly Transparent Photovoltaic Applications

AU - Azhar, Ebraheem Ali

AU - Ye, Weidong

AU - Helfrecht, Benjamin

AU - Chen, George

AU - Thompson, Lucas

AU - Yu, Hongbin

AU - Dey, Sandwip

PY - 2018/7/1

Y1 - 2018/7/1

N2 - Autonomous smart windows may be integrated with a stack of active components, such as electrochromic devices, to modulate the opacity/transparency by an applied voltage. This voltage may be generated with a visibly transparent photovoltaic device. This paper describes the processing and performance of zinc oxide (ZnO) films for integration with electrochromic stacks. Sputtered ZnO (2% Mn) films on indium-tin oxide with transparency in the visible range were used to fabricate metal-semiconductor (MS), metal-insulator-semiconductor, and p-i-n heterojunction devices, and their photovoltaic conversion under ultraviolet (UV) illumination was evaluated with and without oxygen plasma-treated surface electrodes (Au, Ag, Al, and Ti/Ag). The MS Schottky parameters were fit against the generalized Bardeen model to obtain the density of interface states (Dit ≈ 8.0x10¹¹ eV⁻¹cm⁻²) and neutral level (Eo ≈ -5.2 eV). These devices have exhibited a photoconductive behavior at λ = 365 nm, and low-noise Ag-ZnO detectors have exhibited the responsivity (R) and photoconductive gain (G) of 1.93x10⁻⁴ A/W and 6.57x10⁻⁴, respectively. Confirmed via matched-pair analysis, postmetallization oxygen plasma treatment of Ag and Ti/Ag electrodes has resulted in increased Schottky barrier heights, which maximized with a 2-nm SiO₂ electron blocking layer, coupled with the suppression of recombination at the MS interface and blocking of majority carriers. For interdigitated devices under monochromatic UV-C illumination, the open-circuit voltage (Voc) was 1.2 V and short-circuit current density (Jsc), due to minority carrier tunneling, was 0.68 mA/cm².

AB - Autonomous smart windows may be integrated with a stack of active components, such as electrochromic devices, to modulate the opacity/transparency by an applied voltage. This voltage may be generated with a visibly transparent photovoltaic device. This paper describes the processing and performance of zinc oxide (ZnO) films for integration with electrochromic stacks. Sputtered ZnO (2% Mn) films on indium-tin oxide with transparency in the visible range were used to fabricate metal-semiconductor (MS), metal-insulator-semiconductor, and p-i-n heterojunction devices, and their photovoltaic conversion under ultraviolet (UV) illumination was evaluated with and without oxygen plasma-treated surface electrodes (Au, Ag, Al, and Ti/Ag). The MS Schottky parameters were fit against the generalized Bardeen model to obtain the density of interface states (Dit ≈ 8.0x10¹¹ eV⁻¹cm⁻²) and neutral level (Eo ≈ -5.2 eV). These devices have exhibited a photoconductive behavior at λ = 365 nm, and low-noise Ag-ZnO detectors have exhibited the responsivity (R) and photoconductive gain (G) of 1.93x10⁻⁴ A/W and 6.57x10⁻⁴, respectively. Confirmed via matched-pair analysis, postmetallization oxygen plasma treatment of Ag and Ti/Ag electrodes has resulted in increased Schottky barrier heights, which maximized with a 2-nm SiO₂ electron blocking layer, coupled with the suppression of recombination at the MS interface and blocking of majority carriers. For interdigitated devices under monochromatic UV-C illumination, the open-circuit voltage (Voc) was 1.2 V and short-circuit current density (Jsc), due to minority carrier tunneling, was 0.68 mA/cm².

KW - II-VI semiconductor materials

KW - Lighting

KW - Manganese

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KW - photovoltaic detectors

KW - Photovoltaic systems

KW - Schottky barriers

KW - Schottky barriers

KW - semiconductor-insulator interfaces

KW - semiconductor-metal interfaces

KW - ultraviolet (UV) detectors.

KW - Zinc oxide

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