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Transient Negative Capacitance Effect in Atomic‐Layer‐Deposited Al 2 O 3 /Hf 0.3 Zr 0.7 O 2 Bilayer Thin Film
Author(s) -
Kim Keum Do,
Kim Yu Jin,
Park Min Hyuk,
Park Hyeon Woo,
Kwon Young Jae,
Lee Yong Bin,
Kim Han Joon,
Moon Taehwan,
Lee Young Hwan,
Hyun Seung Dam,
Kim Baek Su,
Hwang Cheol Seong
Publication year - 2019
Publication title -
advanced functional materials
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 6.069
H-Index - 322
eISSN - 1616-3028
pISSN - 1616-301X
DOI - 10.1002/adfm.201808228
Subject(s) - materials science , ferroelectricity , capacitance , bilayer , amorphous solid , thin film , dielectric , atomic layer deposition , negative impedance converter , capacitor , condensed matter physics , optoelectronics , analytical chemistry (journal) , nanotechnology , voltage , crystallography , electrical engineering , chemistry , electrode , chromatography , membrane , biology , genetics , engineering , voltage source , physics
The negative capacitance (NC) effect is now attracting a great deal of attention in work towards low‐power operation of field effect transistors and extremely large capacitance density in dynamic random access memory. However, to date, observation of the NC effect in dielectric/ferroelectric bilayer capacitors has been limited to the use of epitaxial ferroelectric thin films based on perovskite crystal structures, such as Pb(Zr,Ti)O 3 and BaTiO 3 , which is not compatible with current complementary metal oxide semiconductor technology. This work, therefore, reports on the transient NC effect in amorphous‐Al 2 O 3 /polycrystalline‐Hf 0.3 Zr 0.7 O 2 bilayer systems prepared using atomic layer deposition. The thin film processing conditions are carefully tuned to achieve the appropriate ferroelectric performances that are a prerequisite for the examination of the transient NC effect. Capacitance enhancement is observed in a wide voltage range in 5–10 nm thick Al 2 O 3 /Hf 0.3 Zr 0.7 O 2 bilayer thin films. It is found that the capacitance of the dielectric layer plays a critical role in the determination of additional charge density induced by the NC effect. In addition, inhibition of the leakage current is important for stabilization of nonhysteretic charge–discharge behavior of the bilayers. The mean‐field approximation combined with classical Landau formalism precisely reproduces the experimental results.