Room-Temperature Negative Capacitance in a Ferroelectric鈥揇ielectric Superlattice Heterostructure

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• 作者：Weiwei Gao ; Asif Khan ; Xavi Marti ; Chris Nelson ; Claudy Serrao ; Jayakanth Ravichandran ; Ramamoorthy Ramesh ; Sayeef Salahuddin
• 刊名：Nano Letters
• 出版年：2014
• 出版时间：October 8, 2014
• 年：2014
• 卷：14
• 期：10
• 页码：5814-5819
• 全文大小：397K
• ISSN：1530-6992

文摘

We demonstrate room-temperature negative capacitance in a ferroelectric鈥揹ielectric superlattice heterostructure. In epitaxially grown superlattice of ferroelectric BSTO (Ba_0.8Sr_0.2TiO₃) and dielectric LAO (LaAlO₃), capacitance was found to be larger compared to the constituent LAO (dielectric) capacitance. This enhancement of capacitance in a series combination of two capacitors indicates that the ferroelectric was stabilized in a state of negative capacitance. Negative capacitance was observed for superlattices grown on three different substrates (SrTiO₃ (001), DyScO₃ (110), and GdScO₃ (110)) covering a large range of substrate strain. This demonstrates the robustness of the effect as well as potential for controlling the negative capacitance effect using epitaxial strain. Room-temperature demonstration of negative capacitance is an important step toward lowering the subthreshold swing in a transistor below the intrinsic thermodynamic limit of 60 mV/decade and thereby improving energy efficiency.

Keywords:

Room-temperature negative capacitance; ferroelectric; superlattice; epitaxial strain