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Software Tool for Seamless Parameter Extraction and Characterization of Schottky Barrier Diodes based on Emerging Implicit Differentiable Models
[Project's page]

Coordinated by: Gheorghe Pristavu

Other persons involved in the project

Răzvan Pascu (CS II), Dan-Theodor Oneață (CS III), Andrei Enache (drd.), Matei Șerbănescu (drd.)

Description:

Project no. TE 17 ⁄ 2022 (UPB: CAMP 2204)
Project Coordinator – POLITEHNICA University Bucharest

The software app is available here!

The project objectives are:

  1. Validating the existing p-diode model equations and investigating extension possibilities which allow for SBD characterization over the widest usable temperature range (from cryogenic up to 675K).
  2. Implementing a parameter extraction and optimization algorithm based on implicit differentiable techniques (IDTs) with the underlying p-diode model. Developing a software tool for seamless SBD characterization.
  3. Fabricating SiC Schottky barrier diodes with different areas and metal-semiconductor contacts (Ni, Pt, Cr, Ti/4H-SiC).
  4. Establishing a data bank with forward characteristics of SDBs with different contact areas and Schottky metals.

Phase 1. Preliminary electrical measurements, analysis of optimal parameterization techniques and technological flow design.

Phase I, taking place in 2022, is focused on identifying appropriate techniques for extracting and optimizing Schottky diode parameters. It is also aimed at experimental investigations of Schottky diodes on SiC. Specifically, a database with forward measurements will be developed, which will serve to validate the parameterization software solution. In order to enhance the stock of UPB's experimental devices, phase I also targets the development of technological processes for manufacturing new batches of Schottky diodes on SiC.

Phase 1 results:

  • Research report
  • Three conference participations (CAS 2022, ICSCRM 2022) leading to 2 papers being published in proceedings, and one being presented as a poster:
    1. R. Pascu, G. Pristavu, M. Stoian, C. Romanitan, M. Kusko, F. Draghici, D.-T. Oneata, G. Brezeanu , &quot;The effect of forming gas annealing on Al/Ti/n-Si contacts,&quot; 2022 International Semiconductor Conference (CAS), 2022, pp. 127-130, doi: 10.1109/CAS56377.2022.9934472.
    2. V. Moise, F. Draghici, G. Pristavu, R. Pascu, D. -T. Oneata, G. Brezeanu, &quot;Intelligent Temperature Sensor with SiC Schottky Diode,&quot; 2022 International Semiconductor Conference (CAS), 2022, pp. 123-126, doi: 10.1109/CAS56377.2022.9934369.
    3. V. Moise, F. Draghici, G. Pristavu, R. Pascu, F. Mitu, G. Brezeanu, &quot;Wide Range Temperature Sensor with SiC Schottky Diode – Error Source Analysis,&quot;, prezentare poster la The 19th edition of the International Conference on Silicon Carbide and Related Materials (ICSCRM), 11-16 Sept., 2022.
  • Project web-page

Fig. 1.1 Low temperature characterization system for Schottky diodes on SiC.

Fig. 1.2 High temperature characterization system for Schottky diodes on SiC.


Fig. 1.3 Forward characteristics and theoretical modeling for a Ti/4H-SiC Schottky diode at various temperatures.


Fig. 1.4 Forward characteristics and theoretical modeling for a Ni/4H-SiC Schottky diode at various temperatures.

 

Phase 2. Initial implementation of the software tool for Schottky diode characterization. Validation on new batches of SiC devices.

Phase II, taking place in 2023, is focused on the development of an initial version of software tool which enables the extraction and optimization of Schottky diode parameters. The investigations performed on Schottky devices, this time on both SiC and Si, are continued. The purpose is to extend the forward characteristics repository available for preliminary validation of the software tool. The stock of UNSTPB experimental devices was extended by the fabrication of new batches of Schottky diodes, especially with Pt/4H-SiC and Cr/4H-SiC contacts.

Preliminary testing, on experimental data, of the characterization software, based on implicit differentiable models, evinced good operation conformity and lead to the identification of possible future optimization in Phase III.

Fig. 2.1. Sample characterization of SiC-Schottky diode experimental forward curves using initial implementation of the IDT software tool

Phase 2 Results:

  • Research report.
  • Three conference participations (ATOM, CAS 2023, ICSCRM 2023) leading to 2 papers being published in proceedings, and another 2 being presented as posters:
    1. G. Brezeanu, G. Pristavu, R. Pascu, and F. Draghici "Schottky diode on Silicon Carbide (SiC): ideal detector for very wide temperature range sensors", Proc. SPIE 12493, Advanced Topics in Optoelectronics, Microelectronics, and Nanotechnologies XI, 1249303 (2 March 2023); https://doi.org/10.1117/12.2644249
    2. G. Pristavu, D. T. Oneata, R. Pascu, M. Serbanescu, A. Enache, F. Draghici, G. Brezeanu , "Modeling forward characteristics of high temperature capable Schottky diodes – High-accuracy optimization methods –," 2023 International Semiconductor Conference (CAS), Sinaia, Romania, 2023, pp. 85-88, doi: 10.1109/CAS59036.2023.10303668.
    3. G. Pristavu, D. T. Oneata, R. Pascu, F. Draghici, G. Brezeanu, "Implicit Differentiable Models for Wide Temperature Range SiC Schottky Diode Characterization", poster presentation at The 20th edition of the International Conference on Silicon Carbide and Related Materials (ICSCRM 2023), 17-22 Sept., 2023.
    4. R. Pascu, G. Pristavu, G. Brezeanu, "Shallow interface states in SiC MOS devices fabricated by oxidation of amorphous silicon thin films", poster presentation at The 20th edition of the International Conference on Silicon Carbide and Related Materials (ICSCRM 2023), 17-22 Sept., 2023.
  • One scientific paper published in high-profile journal:
    1. R. Pascu, G. Pristavu, D. T. Oneata, M. Stoian, C. Romanitan, M. Kusko, F. Draghici, G. Brezeanu (2023). Enhanced Method of Schottky Barrier Diodes Performance Assessment. SCIENCE AND TECHNOLOGY, 26(2), 181-192.
  • Two scientific papers in review at hig-profile journals (IEEE Transactions on Electron Devices and Materials)
  • One specialized book
    1. G. Pristavu, Modelare și instrumentație software pentru caracterizarea diodelor Schottky, București, Editura Matrix Rom. 2023, ISBN 978-606-25-0799-2, CZU 62004

 

Phase 3. Completion of the Software tool for unitary parameter extraction and characterization of Schottky diodes.

Following phase III, carried out in 2024, the final version of the software tool that enables the extraction and optimization of Schottky diode parameters was developed. It was validated on sets of experimental measurements and made available online at https://sbd-specs.dcae.pub.ro. The following improvements have been made:

  • Extension of optimization facilities by adding new input parameters. These are
    • Richardson's constant (An), dependent on the type of semiconductor (SiC, Si, etc.);
    • range of currents (Imin, Imax), which changes the domain of values for which the optimization is performed and the results are displayed.
  • Stabilization of the optimization process by constraining the resistance values to physically plausible ranges. This modification avoids some of the convergence errors, which appeared especially for high learning rates. In the final version of the application, the lower threshold for series resistances is 1Ω.
  • Exposing the application as an Application Programming Interface (API) by restructuring the code. Two endpoints, /predict and /fit, are provided, compatible with HTTP POST requests:
    • /predict calculates forward currents with the p-diode model, using model parameters, temperature range and voltage range as inputs, essentially simulating forward characteristics for the investigated diodes;
    • /fit performs the actual characterization process, by optimizing the diode parameters.

Thus, the results of our software tool can be used programmatically by other applications, developed in various programming languages. The current version is hosted within the DCAE department’s infrastructure, installed on a virtual machine running Ubuntu 22.04 LTS. It is available at http://sbd-specs.dcae.pub.ro:8535/.

All the activities in the project plan were completed, reaching the objectives set out in the project proposal. The results obtained following the implementation of the project are in line with the estimated ones.

 


Fig. 3.1 Software tool for unitary parameter extraction and characterization of Schottky diodes – user interface.

Phase 3 Results:

  • Research report.
  • Two scientific papers published in high-profile journals:
    1. G. Pristavu, G. Brezeanu, D. T. Oneata, R. Pascu, F. Draghici, M. Serbanescu, A. Enache (2024), Lagging Thermal Annealing for Barrier Height Uniformity Evolution of Ni/4H-SiC Schottky Contacts. IEEE Transactions on Electron Devices, 71(4), 2805-2809.
    2. R. Pascu, G. Pristavu, D. T. Oneata, G. Brezeanu, C. Romanitan, N. Djourelov, A. Enache, F. Draghici, A. M. Ivan, E. Ceuca (2024), Thorough Wide-Temperature-Range Analysis of Pt/SiC and Cr/SiC Schottky Contact Non-Uniformity. Materials, 17(2), 400.
  • One scientific paper accepted in high-profile journal (Romanian Journal of Information Science and Technology)