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C3.3 MBE growth kinetics and doping of (Ga,Al)2O3



Overview of the research project:

This project will investigate the growth and doping of (Ga,Al)2O3 and their heterostructures by plasma-assisted molecular beam epitaxy. Besides high material quality and defined doping, the project aims to improve modelling of the growth kinetics. The materials focus is on the Al-containing oxides due to their large band gap. The project comprises the following tasks whose complexity requires a PostDoc:

Task 1. Device quality, doped Ga2O3. The homoepitaxy of Ga2O3 is optimized to obtain device quality material with defined doping.

Task 2. Growth kinetics and suboxides
The project characterizes the composition and rate by quadrupole mass spectrometry of the flux from suboxide sources for MBE based on sublimation of the oxide (Ga2O3, In2O3, SnO2) or mixture of oxide and its corresponding metal. Using these sources, the oxide growth kinetics for Ga2O3, In2O3, and (In,Ga)2O3 growth are measured and compared to the known results when using metal sources. The growth rate and desorption are measured by in-situ by laser reflectometry and in-situ line-of-sight quadrupole mass spectrometry, respectively, and all results are used to improve an existing basic growth kinetics model.

Task 3. Growth of Al-containing oxides
The growth of Al2O3 and its alloys with Ga2O3 and In2O3 is developed and its growth kinetics studied and modeled. Starting point is the growth on the alpha-phase with high-Al content on Al2O3 substrates. Doping of the alloy is investigated and heterostructures are grown with these alloys.

Task 4. Hydrogen doping
After developing and commissioning a H2O injector, the binary oxides In2O3, Ga2O3 and SnO2 are doped by Hydrogen using H2O or D2O as precursor and the resulting transport properties are investigated to clarify the role of hydrogen as a donor.

Major accomplishments expected:

  • Device quality, doped Ga2O3 for collaborators

  • Potentially new, advantageous paradigm for oxide MBE using suboxide sources.

  • Detailed understanding of growth processes towards an atomistic level

  • Al-containing sesquioxides with high material quality

  • Understand the role of hydrogen in oxides


Collaboration with partners in the project:

  • Non-Al2O3 substrates: Matthias Bickermann

  • Structural investigations: Michael Hanke, Christoph Koch/Martin Albrecht, Manfred Ramsteiner

  • Growth surface theory: Claudia Draxl, Matthias Scheffler

  • Surface adsorbates: Mattia Mulazzi, Holger Eisele

  • Point defects and doping: Manfred Ramsteiner, Ted Masselink, Martin Albrecht, Klaus Irmscher


The Research Team


Piero Mazzolini

Piero Mazzolini is from Tolmezzo, Italy. He received his PhD in “energy and nuclear science and technology” at the Politecnico di Milano in 2015 working on the Pulsed Laser Deposition and characterization of doped oxides for transparent electronics (TiO2, ZnO). As a postdoc at the Italian Institute of Technology (CNST–Milan), he has been involved in the realization of thin film-based prototype devices deposited via Physical Vapor Deposition techniques. He is actually working on the MBE growth of Ga2O3 thin films at the Paul Drude Institute in Berlin since October 2017.


Project lead

If you have queries about the project, please contact the PI:
Oliver Bierwagen, Paul-Drude-Institut




Logo Leibniz-Gemeinschaft

The Leibniz ScienceCampus GraFOx is a network of two Leibniz Institutes, two universities and one institute of the Max Planck Society. It is based in Berlin, Germany.


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Kai Hablizel

Paul-Drude Institut für Festkörperelektronik (PDI)
Leibniz-Institut im Forschungsverbund Berlin e.V.
Tel.: +49 30 20377-342




Prof. Dr. Henning Riechert, PDI

Scientific Coordinator:

Dr. Oliver Bierwagen, PDI
Dr. Martin Albrecht, IKZ