Controllable giant dielectric constant in AlOx/TiOy nanolaminates

Abstract

Dielectric materials exhibiting high dielectric constants play critical roles in a wide range of applications from microchip energy storage embedded capacitors for implantable biomedical devices to energy storage capacitors for a new generation of renewable energy generation/storage systems. Instead of searching for new materials, we demonstrate that giant dielectric constants can be achieved by integrating two simple oxides with low dielectric constants into nanolaminate structures. In addition, the obtained dielectric constant values are highly tunable by manipulating the sub-layer thicknesses of the component oxides to control the number of interfaces and oxygen redistribution. The work reported here opens a new pathway for the design and development of high dielectric constant materials based on the nanolaminate concept.

Enhancement of the maximum energy density in atomic layer deposited oxide based thin film capacitors

“…Since several material systems, such as Al 2 O 3 , 1,2 HfO 2 , 3,4 TiO 2 , 5 and ZrO 2 , 6 are commonly used materials for oxide based thin film capacitors, they have been studied in several aspects. These are, for example, the frequency and layer thickness dependent permittivity, 5 the influence of electrode materials on the electrical stability of the dielectric, 1 and mechanisms to increase their breakdown stability 7 and reliability 2,8 and leakage conduction mechanisms. 9 The capacitive areas reported about in the recent literature refer to small capacitive areas significantly below 1 mm 2 , 10,11 or do not give information about the area of the examined capacitive structures.…”

“…Thickness dependent volume energy densities of up to 50 J/cm 3 for pure Al 2 O 3 and 60 J/cm 3 Oxide based thin film capacitors and transistors are recently discussed regarding, for example, material dependent capacitances, breakdown behavior, and leakage current characteristics. Since several material systems, such as Al 2 O 3 , 1,2 HfO 2 , 3,4 TiO 2 , 5 and ZrO 2 , 6 are commonly used materials for oxide based thin film capacitors, they have been studied in several aspects. These are, for example, the frequency and layer thickness dependent permittivity, 5 the influence of electrode materials on the electrical stability of the dielectric, 1 and mechanisms to increase their breakdown stability 7 and reliability 2,8 and leakage conduction mechanisms.…”

“…Nanolaminate structured dielectrics based on Al 2 O 3 / TiO 2 are also discussed by Li et al 5 They report about the possibility of giant relative permittivities by varying the sublayer thicknesses of their nanolaminates. In contrast, the sublayer thicknesses are kept equal in this work.…”

Aluminum oxide/titanium dioxide nanolaminates grown by atomic layer deposition: Growth and mechanical properties

“…20 In mixed oxides 21 (Al2O3 and TiO2) and Al2O3 / TiO2 nanolaminates, 22 tailored optical properties varying from Al2O3 to TiO2 with gradual composition change have been demonstrated. Electrical properties 23,24 can be tuned by adjusting either the TiO2 fraction 25,26 or the bilayer thickness 27,28,29,30 or with an interfacial layers. 31 The effect of alloying elements on controlling the grain size is well known in bulk materials.…”

Preparation and properties of ZrO2 and TiO2 films and their nanolaminates by atomic layer deposition

“…This giant dielectric constant may originate from the Maxwell-Wagner-type dielectric relaxation between semiconducting TiO 2 and insulating ZrO 2 nanolayers. The Maxwell-Wagner type dielectric relaxation was also found in AlO x and TiO x nanolaminates [13][14][15][16]. The loss tangent was 0.30 at 1 kHz.…”