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Overview Dielectrics

Fig. 1:  ALD based materials as gate dielectrics in nanowire and ferroelectric field effect transistors.

Materials with high dielectric constant (high-k materials) play an increasingly important role in nano-electronic devices. For example, in conventional semiconductors charge is stored in
capacitors with a dielectric insulation layer. In order to maintain the storage capacity of capacitors, new dielectric materials with higher dielectric constants have to be introduced for devices with smaller area. Similar dielectric materials are needed for the next generation of high performance transistor devices as well as processors and logic products. A variety of research projects in the nano-scale regime are ongoing in order to gain an understanding of the influence of material properties with respect to leakage mechanisms, performance, speed and reliability.

As depicted in the schematic below, a set of five main material systems (Al2O3, HfO2, TiO2, ZrO2, and SiO2) is used for different dielectric applications. Accordingly, a detailed understanding of the structural and electrical properties gained on one device application can be used as a fundamental basic knowledge for future new devices. The impact of process properties on the device performance can be correlated. Especially, the optimization of charges and traps, dielectric constants, material properties like density, dielectric, piezoelectric, ferroelectric, and optical properties are important for the various device applications.

Fig. 2: Deposition of ALD Al2O3 dielectrics within a GaN HEMT device.

NaMLab also screens and characterizes further candidate materials like Nb2O5, SrO2, Sc2O3 and CaTiO3 for novel device applications. Additional new dielectrics will follow. Materials are deposited by molecular beam deposition (MBD), atomic layer deposition (ALD), chemical vapor deposition (CVD), and physical vapor deposition (PVD). NaMLab investigates a wide range of applications of dielectrics for nanowire transistors (Fig. 1), GaN HEMT devices (Fig. 2), capacitors to porous structures (Fig. 3).

Fig. 3: Deposition of ALD dielectrics on a
porous electrode with high surface area.


Capacitor Dielectrics

Diffusion Barriers

Ferroelectric Materials

High-k on Gallium Nitride

Piezo- and Pyroelectric Materials


Contact: Dr. Uwe Schroeder


NaMLab gGmbH
Nöthnitzer Str. 64 a
01187 Dresden

Phone: +49.351.21.24.990-00
Fax: +49.351.475.83.900

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NaMLab gGmbH is financed in parts by the Saxon State government out of the State budget approved by the Saxon State Parliament.

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