Abstract: This document provides a description of the use of the device cycle of the IM2D Simulation box to extract material and defect properties from the interpretation of the electrical current-voltage (I-V) characteristics measured on Ovonic Threshold Switching (OTS) selector devices. The task activities rely on the use of the Defect Discovery Tool (DDT) functionalities implemented into AMAT proprietary GinestraTM platform, that are specifically developed to extract intrinsic material/device properties (bandgap, thicknesses) and characteristics of the defects (thermal ionization and relaxation energies, distribution within the bandgap) from electrical measurements. Further details on DDT can be found in Sec 3.2 of Deliverable 3.1.
DDT functionalities are applied to current-voltage and conductance-voltage (G-V) characteristics measured on GeSe-based OTS devices with different thicknesses (10nm and 20nm) and compositions (Ge60Se40 and Ge50Se50). Capacitance-Voltage characteristics (C-V) are used to provide an estimation of the relative dielectric permittivity of the GeSe film. All devices and electrical measurements are provided by the IMEC unit.
Consistent results are obtained for all the considered samples. Derived material parameters (band-gap and relative dielectric permittivity) well agree with reports in literature and with the Density Functional Theory (DFT) calculations performed within the project and presented in this Deliverable. An increase of GeSe band-gap is observed as the Ge content of the film is reduced (from Ge60Se40 to Ge50Se50).
The experimental I-V characteristics and their temperature dependence are well explained by a trap-assisted carrier transport, occurring through a defect-band located close to the GeSe valence band minima. The traps energy levels (within the band-gap) extracted with the DDT functionalities are found to be in good agreement with the values reported in Selenium vacancies (VSe) literature. However, a precise identification of the defect atomic structure is not straightforward, since the value of the relaxation energy cannot be unambiguously identified.

Info & download: A. Padovani, S. Clima, B. Kackzer, L. Medondjio, X. He, P. Ordejón, and A. Calzolari (2020): Atomic defect properties from the electrical measurements on GeSe OTS selectors. Deliverable D3.2 of the H2020 project INTERSECT (final version as of 28/07/2020). EC grant agreement no: 814487, Applied Materials, Reggio Emilia, Italy.

Executive summary: This document provides a description of the use of the device cycle of the IM2D Simulation box to extract material and defect properties from the interpretation of the electrical data measured on ferroelectric devices.
The task activities rely on the use of the Defect Discovery Tool (DDT) functionalities implemented into AMAT proprietary Ginestra^TM platform, which are specifically developed to extract intrinsic material/device properties (e.g. bandgap, thicknesses, etc.) and characteristics of the defects (e.g. thermal ionization and relaxation energies, distribution within the bandgap) from electrical measurements.
DDT functionalities are applied to current-voltage and threshold voltage shifts (ΔV_T) characteristics measured respectively on Silicon-Ferroelectric-Silicon (SFS) capacitors and high-k/metal gate (HKMG) ferroelectric transistors with doped FE-HfO₂. Devices and electrical measurements are provided by IMEC and FMC units.
Consistent results are obtained for the data and devices considered and show that both charge transport and ΔV_T are originated by a different trap state with respect to the ones typically reported for conventional HfO₂. The similarities found between the properties extracted using the DDT for the defects in doped HfO₂ of both SFS and HKMG devices suggest that these traps may be related to specific features of the FE-HfO₂ structure that are at the bases of the ferroelectricity in this material.

Info & Download: Padovani, A., Ocker, J., Kaczer, B., Calzolari, A. (2020): “Atomic defect properties from the electrical measurements on FE-HfO₂-devices. Deliverable D3.1 of the H2020 project INTERSECT” (final version as of 30/01/2020), EC grant agreement no: 814487, Applied Materials, Reggio-Emilia, Italy.

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