Nanofabrication

Semiconducting oxides

Oxides are among the materials with the widest tunability of physical properties. Spanning insulators, semiconductors, metallic conductors and superconductors, magnetic materials, ferro-/antiferro- and other dielectrics, oxides are a materials class with high potential for a new generation of electronic devices for energy and sensing applications.

Traditionally, oxides have been synthesized by pulsed laser deposition or sputtering, which both have drawbacks in terms of material quality. A higher material quality can be achieved by molecular beam epitaxy (MBE), which is the growth method used by us.

Our research aims at exploring the properties of semiconducting oxides at the materials limit, equally taking into account the understanding of the growth thermodynamics and kinetics as well as the materials application perspective. Providing samples for (international) collaborations is an important part of our scientific culture. To date, our materials portfolio comprises the n-type oxides (Ga,In,Al)₂O₃, SnO₂, the perovskites BaSnO₃ and LaInO₃, as well as the p-type oxides SnO and (the antiferromagnet) NiO. Out of these SnO₂, NiO, and In₂O₃ are frequently used in conductometric gas sensing—an application whose fundamental investigation together with external collaborators greatly benefits from our well-defined samples. Energy-efficient power electronics as well as solar-blind UV sensing are further important applications, both of which are foreseen to profit tremendously from the ultra-wide bandgap semiconductor Ga₂O₃ and its solid solutions with In₂O₃ and Al₂O₃. For the same purpose, we recently started investigating rutile-GeO₂ and its solid solutions with SnO₂ and SiO_2.

Embedded in the Berlin-based Leibniz ScienceCampus „Growth and fundamentals of oxides for electronic applications“ (GraFOx), led by PDI, our activities are currently divided into the following projects:

Metastable III₂O₃ alloys, deep acceptor-doping, and p-type oxides
MBE of LaInO₃/BaSnO₃ heterostructures for electronic applications (funding in Leibniz competition “BaSnO₃-based heterostructures for electronic applications”)

Point defects control in Ga₂O₃ thin films grown via molecular beam epitaxy (funded by DFG)
(Si,Ge,Sn)O₂-based ultra-wide bandgap semiconductors for power electronics (funding in Leibniz competition)

Selected Publications

5	Author	K. Tetzner , K. O. Egbo , M. Klupsch , R.-S. Unger , A. Popp , T.-S. Chou , S. Bin Anooz , Z. Galazka , A. Trampert , O. Bierwagen , J Würfl
	Title	SnO/β-Ga2O3 heterojunction field-effect transistors and vertical p-n diodes
	Source	Appl. Phys. Lett. , 120 , 112110 ( 2022 )
DOI : 10.1063/5.0083032 \| Download: PDF \| 3287 Cite : Bibtex RIS @article{ author = { K. Tetzner and K. O. Egbo and M. Klupsch and R.-S. Unger and A. Popp and T.-S. Chou and S. Bin Anooz and Z. Galazka and A. Trampert and O. Bierwagen and J Würfl }, title = { SnO/β-Ga2O3 heterojunction field-effect transistors and vertical p-n diodes }, journal = { Applied Physics Letters }, volume = { 120 }, year = { 2022 }, pages = { 112110 } } K. Tetzner, K. O. Egbo, M. Klupsch, R.-S. Unger, A. Popp, T.-S. Chou, S. Bin Anooz, Z. Galazka, A. Trampert, O. Bierwagen, and J Würfl TY - JOUR AU - K. Tetzner AU - K. O. Egbo AU - M. Klupsch AU - R.-S. Unger AU - A. Popp AU - T.-S. Chou AU - S. Bin Anooz AU - Z. Galazka AU - A. Trampert AU - O. Bierwagen AU - J Würfl TI - SnO/β-Ga2O3 heterojunction field-effect transistors and vertical p-n diodes JF - Applied Physics Letters JA - Appl. Phys. Lett. J1 - APL VL - 120 SP - 112110 PY - 2022/03/18

4	Author	J. Feldl , M. Feneberg , A. Papadogianni , J. Lähnemann , T. Nagata , O. Bierwagen , R. Goldhahn , M. Ramsteiner
	Title	Band gap widening and phonon behavior of cubic single-crystalline (In,Ga)2O3 alloy ﬁlms
	Source	Appl. Phys. Lett. , 119 , 042101 ( 2021 )
DOI : 10.1063/5.0056532 \| Download: PDF \| 3241 Cite : Bibtex RIS @article{ author = { J. Feldl and M. Feneberg and A. Papadogianni and J. Lähnemann and T. Nagata and O. Bierwagen and R. Goldhahn and M. Ramsteiner }, title = { Band gap widening and phonon behavior of cubic single-crystalline (In,Ga)2O3 alloy ﬁlms }, journal = { Applied Physics Letters }, volume = { 119 }, year = { 2021 }, pages = { 042101 } } J. Feldl, M. Feneberg, A. Papadogianni, J. Lähnemann, T. Nagata, O. Bierwagen, R. Goldhahn, and M. Ramsteiner TY - JOUR AU - J. Feldl AU - M. Feneberg AU - A. Papadogianni AU - J. Lähnemann AU - T. Nagata AU - O. Bierwagen AU - R. Goldhahn AU - M. Ramsteiner TI - Band gap widening and phonon behavior of cubic single-crystalline (In,Ga)2O3 alloy ﬁlms JF - Applied Physics Letters JA - Appl. Phys. Lett. J1 - APL VL - 119 SP - 042101 PY - 2021/07/29

3	Author	O. Bierwagen , P. Vogt , P. Mazzolini
	Title	Gallium Oxide - Plasma-Assisted Molecular Beam Epitaxy 2—Fundamentals of Suboxide-Related Growth Kinetics, Thermodynamics, Catalysis, Polymorphs, and Faceting
	Source	Springer Series in Materials Science , 293 , 95 ( 2020 )
DOI : 10.1007/978-3-030-37153-1_6 \| 3184 Cite : Bibtex RIS @article{ author = { O. Bierwagen and P. Vogt and P. Mazzolini }, title = { Gallium Oxide - Plasma-Assisted Molecular Beam Epitaxy 2—Fundamentals of Suboxide-Related Growth Kinetics, Thermodynamics, Catalysis, Polymorphs, and Faceting }, journal = { Springer Series in Materials Science }, volume = { 293 }, year = { 2020 }, pages = { 95 } } O. Bierwagen, P. Vogt, and P. Mazzolini TY - JOUR AU - O. Bierwagen AU - P. Vogt AU - P. Mazzolini TI - Gallium Oxide - Plasma-Assisted Molecular Beam Epitaxy 2—Fundamentals of Suboxide-Related Growth Kinetics, Thermodynamics, Catalysis, Polymorphs, and Faceting JF - Springer Series in Materials Science JA - J1 - VL - 293 SP - 95 PY - 2020/04/24

2	Author	G. Hoffmann , M. Budde , P. Mazzolini , O. Bierwagen
	Title	Efficient suboxide sources in oxide molecular beam epitaxy using mixed metal + oxide charges: The examples of SnO and Ga2O
	Source	APL Mater. , 8 , 031110 ( 2020 )
DOI : 10.1063/1.5134444 \| Download: PDF \| 3152 Cite : Bibtex RIS @article{ author = { G. Hoffmann and M. Budde and P. Mazzolini and O. Bierwagen }, title = { Efficient suboxide sources in oxide molecular beam epitaxy using mixed metal + oxide charges: The examples of SnO and Ga2O }, journal = { APL Materials }, volume = { 8 }, year = { 2020 }, pages = { 031110 } } G. Hoffmann, M. Budde, P. Mazzolini, and O. Bierwagen TY - JOUR AU - G. Hoffmann AU - M. Budde AU - P. Mazzolini AU - O. Bierwagen TI - Efficient suboxide sources in oxide molecular beam epitaxy using mixed metal + oxide charges: The examples of SnO and Ga2O JF - APL Materials JA - APL Mater. J1 - APLM VL - 8 SP - 031110 PY - 2020/03/12

1	Author	J. Rombach , A. Papadogianni , M. Mischo , V. Cimalla , L. Kirste , O. Ambacher , T. Berthold , S. Krischok , M. Himmerlich , Sören Selve , O. Bierwagen
	Title	The role of surface electron accumulation and bulk doping for gas-sensing explored with single-crystalline In2O3 thin films
	Source	Sens. Actuators B Chem. , 236 , 909 ( 2016 )
DOI : 10.1016/j.snb.2016.03.079 \| 2784 Cite : Bibtex RIS @article{ author = { J. Rombach and A. Papadogianni and M. Mischo and V. Cimalla and L. Kirste and O. Ambacher and T. Berthold and S. Krischok and M. Himmerlich and Sören Selve and O. Bierwagen }, title = { The role of surface electron accumulation and bulk doping for gas-sensing explored with single-crystalline In2O3 thin films }, journal = { Sensors & Actuators B }, volume = { 236 }, year = { 2016 }, pages = { 909 } } J. Rombach, A. Papadogianni, M. Mischo, V. Cimalla, L. Kirste, O. Ambacher, T. Berthold, S. Krischok, M. Himmerlich, Sören Selve, and O. Bierwagen TY - JOUR AU - J. Rombach AU - A. Papadogianni AU - M. Mischo AU - V. Cimalla AU - L. Kirste AU - O. Ambacher AU - T. Berthold AU - S. Krischok AU - M. Himmerlich AU - Sören Selve AU - O. Bierwagen TI - The role of surface electron accumulation and bulk doping for gas-sensing explored with single-crystalline In2O3 thin films JF - Sensors & Actuators B JA - Sens. Actuators B Chem. J1 - VL - 236 SP - 909 PY - 2016/03/18