TY - JOUR
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
N1 - Funding Information:
Manuscript received January 26, 2018; revised March 19, 2018; accepted March 20, 2018. Date of publication July 2, 2018; date of current version July 23, 2018. This work was supported by the National Science Foundation under Grant 1143570. The review of this paper was arranged by Editor A. G. Aberle. (Corresponding author: Ebraheem Ali Azhar.) E. A. Azhar and H. Yu are with the School of Electrical, Computer and Energy Engineering, Arizona State University, Tempe, AZ 85281 USA (e-mail: eazhar@asu.edu; hongbin.yu@asu.edu).
Publisher Copyright:
© 1963-2012 IEEE.
PY - 2018/8
Y1 - 2018/8
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 ≈ 8.0 × 1011 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 1.93 × 10-4 A/W and 6.57 × 10-4 , 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 ≈ 8.0 × 1011 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 1.93 × 10-4 A/W and 6.57 × 10-4 , 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 - Photovoltaic cells
KW - Schottky barriers
KW - photovoltaic detectors
KW - semiconductor-insulator interfaces
KW - semiconductor-metal interfaces
KW - ultraviolet (UV) detectors
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U2 - 10.1109/TED.2018.2823308
DO - 10.1109/TED.2018.2823308
M3 - Article
AN - SCOPUS:85049445230
SN - 0018-9383
VL - 65
SP - 3291
EP - 3299
JO - IEEE Transactions on Electron Devices
JF - IEEE Transactions on Electron Devices
IS - 8
M1 - 8401946
ER -