Achieving ultrahigh breakdown strength and energy storage

the anodized Al2O3 to be the blocking layer, not only the local high electric ... energy storage density by means of increasing the dielectric constan...
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Functional Inorganic Materials and Devices

Achieving ultrahigh breakdown strength and energy storage performance through periodic interface modification in SrTiO thin film 3

Wenbin Gao, Manwen Yao, and Xi Yao ACS Appl. Mater. Interfaces, Just Accepted Manuscript • DOI: 10.1021/acsami.8b07151 • Publication Date (Web): 20 Jul 2018 Downloaded from http://pubs.acs.org on July 20, 2018

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ACS Applied Materials & Interfaces

Achieving ultrahigh breakdown strength and energy storage performance through periodic interface modification in SrTiO3 thin film Wenbin Gao, † Manwen Yao, * ‡ and

Xi Yao †



Electronic Materials Research Laboratory, Key Laboratory of the Ministry of Education &

International Center for Dielectric Research, School of Electronic and Information on Engineering, Xi’an Jiao tong University, Xi’an 710049, China. ‡

Functional Materials Research Laboratory, School of Materials Science and Engineering, Tong ji

University, Shanghai 200092, China.

ABSTRACT: A periodic layer structure consisting of sol-gel derived SrTiO3 and anodized Al2O3 has been designed and fabricated by interface engineering. Utilizing the anodized Al2O3 to be the blocking layer, not only the local high electric field around the hole and crack defects could be significantly reduced but also, and equally important, the blocking layer undertaking higher electric field could effectively decrease the breakdown probability of SrTiO3 layer based on the finite element analysis. As the sample has been modified, the barrier height of the charge carrier was increased through fitting the conductance activation energy (Hc). In addition, the space charge limited conductance (SCLC) conductance mechanism was almost eliminated according to the fitted results in the LnE - LnJ diagram, indicating that most of the charge carrier released from traps were blocked or isolated by the Al2O3 layer. As a result of the periodic interface modification, the leakage current was decreased two orders of magnitude and breakdown strength was enhanced from 144.13MV m-1 to 754.23 MV m-1. More importantly, the ultimate energy density is up to 39.49 J cm-3, which is 1505% greater than the the sample without interface modification. KEYWORDS: amorphous SrTiO3, interface modification, anodic oxidation, breakdown strength, energy density

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1. INTRODUCTION As a critical device in pulse power system, the importance of high power density storage capacitor is increasing with the development of new energy vehicle, electromagnetic gun and high energy laser weapon.1-7 The excellent performance of ultrafast charge-discharge capability enables dielectric capacitor to be the primary choice.8 However, a crucial problem of low energy storage density (≤ 2 J cm-3) is remaining to be addressed, which severely limits its development and application. As shown in equation (1), the calculation principle of energy storage density is determined by electric displacement (D) and applied field (E), where D can be given by D=ε0εrE.9,10 With respect to linear dielectrics, equation (1) can be transformed to the form of equation (2). In general, increased dielectric constant is usually achieved at the cost of substantially decreased breakdown strength. For instance, high dielectric constant (>1000) of ferroelectrics (BaTiO3) is usually accompanied by low breakdown strength (