@article{MTMT:31354912,
	title = {Investigation of interfaces and threshold voltage instabilities in normally-off MOS-gated InGaN/AlGaN/GaN HEMTs},
	url = {https://m2.mtmt.hu/api/publication/31354912},
	author = {Pohorelec, O. and Ťapajna, M. and Gregušová, D. and Gucmann, F. and Hasenöhrl, S. and Haščík, Š. and Stoklas, R. and Seifertová, A. and Pécz, Béla and Tóth, Lajos and Kuzmík, J.},
	doi = {10.1016/j.apsusc.2020.146824},
	journal-iso = {APPL SURF SCI},
	journal = {APPLIED SURFACE SCIENCE},
	volume = {528},
	unique-id = {31354912},
	issn = {0169-4332},
	abstract = {Polarization engineering is a promising approach to achieve high positive threshold voltage (Vth) in GaN-based metal-oxide-semiconductor high electron mobility transistors (MOS HEMTs). In this paper, we investigate all critical interfaces of polarization-engineered normally-off Al2O3/InGaN/AlGaN/GaN MOS HEMTs using transmission electron microscopy and X-ray photoelectron spectroscopy. Mechanisms of threshold voltage (VTH) instabilities are also analyzed. Devices were subjected to positive-bias stress-recovery experiments to capture the transient change in Vth. We propose a model that explains observed peculiar behavior and discuss the role of 2-dimensional hole gas (2DHG) in Al2O3/InGaN/AlGaN/GaN MOS HEMTs Vth shift.},
	keywords = {GAN; InGaN; Normally-off transistor; Threshold voltage instabilities},
	year = {2020},
	eissn = {1873-5584},
	orcid-numbers = {Pécz, Béla/0000-0002-4651-6972; Tóth, Lajos/0000-0003-0334-2869}
}

@article{MTMT:30936719,
	title = {GaAs epilayers grown on patterned (001) silicon substrates via suspended Ge layers},
	url = {https://m2.mtmt.hu/api/publication/30936719},
	author = {Ballabio, Andrea and Bietti, Sergio and Scaccabarozzi, Andrea and Esposito, Luca and Vichi, Stefano and Fedorov, Alexey and Vinattieri, Anna and Mannucci, Cosimo and Biccari, Francesco and Nemcsics, Ákos and Tóth, Lajos and Miglio, Leo and Gurioli, Massimo and Isella, Giovanni and Sanguinetti, Stefano},
	doi = {10.1038/s41598-019-53949-x},
	journal-iso = {SCI REP},
	journal = {SCIENTIFIC REPORTS},
	volume = {9},
	unique-id = {30936719},
	issn = {2045-2322},
	year = {2019},
	eissn = {2045-2322},
	orcid-numbers = {Tóth, Lajos/0000-0003-0334-2869}
}

@article{MTMT:30682160,
	title = {InGaN/(GaN)/AlGaN/GaN normally-off metal-oxide-semiconductor high-electron mobility transistors with etched access region},
	url = {https://m2.mtmt.hu/api/publication/30682160},
	author = {Gregušová, Dagmar and Tóth, Lajos and Pohorelec, Ondrej and Hasenöhrl, Stanislav and Haščík, Štefan and Cora, Ildikó and Fogarassy, Zsolt and Stoklas, Roman and Seifertová, Alena and Blaho, Michal and Laurenčíková, Agáta and Oyobiki, Tatsuya and Pécz, Béla and Hashizume, Tamotsu and Kuzmík, Ján},
	doi = {10.7567/1347-4065/ab06b8},
	journal-iso = {JPN J APPL PHYS},
	journal = {JAPANESE JOURNAL OF APPLIED PHYSICS (2008)},
	volume = {58},
	unique-id = {30682160},
	issn = {0021-4922},
	abstract = {The proposal and processing aspects of the prove-of-concept InGaN/GaN/AlGaN/GaN metal-oxide-semiconductor (MOS) high-electron mobility transistor with etched access regions are addressed. Full strain and decent quality of the epitaxial system comprising 4 nm In0.16Ga0.84N/3 nm GaN/5 nm Al0.27Ga0.73N are observed using a high-resolution transmission-electron microscopy and by deformation profile extractions. Large negative polarization charge in the MOS gate stack provides the HEMT normally-off operation, while free electrons are populated at access regions after etching. Consecutive passivation by 10 nm Al2O3 together with annealing at 300 °C improved the Al2O3/semiconductor interface, with the threshold voltage (V T ) reaching 1 V. Improvements of the present concept in comparison to the previous one with a gate recess were proved by showing the decreased drain leakage current and increased breakdown voltage.},
	year = {2019},
	eissn = {1347-4065},
	orcid-numbers = {Tóth, Lajos/0000-0003-0334-2869; Fogarassy, Zsolt/0000-0003-4981-1237; Pécz, Béla/0000-0002-4651-6972}
}

@article{MTMT:27700291,
	title = {Temperature Dependent Vertical Conduction of GaN HEMT Structures on Silicon and Bulk GaN Substrates},
	url = {https://m2.mtmt.hu/api/publication/27700291},
	author = {Heuken, L and Alshahed, M and Ottaviani, A and Alomari, M and Heuken, M and Wächter, C and Bergunde, T and Cora, Ildikó and Tóth, Lajos and Pécz, Béla and Burghartz, JN},
	doi = {10.1002/pssa.201800482},
	journal-iso = {PHYS STATUS SOLIDI A-APPL MAT SCI},
	journal = {PHYSICA STATUS SOLIDI A-APPLICATIONS AND MATERIALS SCIENCE},
	volume = {216},
	unique-id = {27700291},
	issn = {1862-6300},
	year = {2019},
	eissn = {1862-6319},
	orcid-numbers = {Tóth, Lajos/0000-0003-0334-2869; Pécz, Béla/0000-0002-4651-6972}
}

@article{MTMT:30739221,
	title = {Basic restrictions for theories of ion-induced track formation: ignored relationships between experimental data},
	url = {https://m2.mtmt.hu/api/publication/30739221},
	author = {Szenes, György and Tóth, Lajos},
	doi = {10.1088/1402-4896/ab300c},
	journal-iso = {PHYS SCR},
	journal = {PHYSICA SCRIPTA},
	volume = {94},
	unique-id = {30739221},
	issn = {0031-8949},
	abstract = {Ion-induced track data are analyzed without the application of any model for revealing the existing relationships between them. Published data are completed with some new ones. Prethinned Y3Fe5O12 samples were irradiated by C60 ions with 3.5, 5 and 7 MeV energy. Track radii Re were measured by electron microscopy. It was derived from the data that the electronic (Se) and nuclear stopping (Sn) powers are combined as αSe+βSn when they have a simultaneous effect. α=0.45 was derived from experiments on Y3Fe5O12. When using larger database α varies in the range 0.4>α>0.17 with increasing ion energy that is valid for monoatomic irradiations as well, and this is the origin of the reduction of Re with the increasing ion energy in insulators. A Gaussian relationship exists between melting temperatures Tm and track radii in track forming insulators for Se/N=constant (N – atomic number density). Due to this Tm is the unique controlling materials parameter for the track size. Consequences for the parameters of the induced temperature distributions are discussed. The conclusions were deduced directly from the raw experimental data, therefore, the derived relationships should be followed by any theoretical model.},
	year = {2019},
	eissn = {1402-4896},
	orcid-numbers = {Tóth, Lajos/0000-0003-0334-2869}
}

@article{MTMT:3401186,
	title = {Low-Dispersion, High-voltage, Low-Leakage GaN HEMTs on Native GaN Substrates},
	url = {https://m2.mtmt.hu/api/publication/3401186},
	author = {Alshahed, M and Heuken, L and Alomari, M and Cora, Ildikó and Tóth, Lajos and Pécz, Béla and Wachter, C and Bergunde, T and Burghartz, JN},
	doi = {10.1109/TED.2018.2832250},
	journal-iso = {IEEE T ELECTRON DEV},
	journal = {IEEE TRANSACTIONS ON ELECTRON DEVICES},
	volume = {65},
	unique-id = {3401186},
	issn = {0018-9383},
	abstract = {In this paper, the advantages of GaN high electron mobility transistors (HEMTs) grown on native GaN over GaN/Si or GaN/sapphire substrates are investigated and correlated with epitaxial material quality. Transmission electron microscopy plan-view and cross-sectional analyses of GaN/GaN reveal dislocation densities below 1 x 10(6) cm(-2), which is at least three orders of magnitude lower than that of GaN/Si or GaN/sapphire. In the case of GaN/Si, the dislocations not only originate from the substrate/nucleation layer interface, but also the strain relief and isolation buffer stacks are main contributors to the dislocation density. GaN/GaN HEMTs show superior electrical and thermal performance and feature three orders of magnitude lower OFF-state leakage. The current collapse (also referred to as current dispersion or R-ON-increase) after stress bias is less than 15% compared with 50% in the case of GaN/Si. A 2% drop of the ON-state current due to self-heating in dc operation when compared with 13% and 16% for GaN/Si and GaN/sapphire, respectively. The GaN/Si thermal performance becomes comparable to that of GaN/GaN only after substrate removal. Therefore, GaN/GaN provides high ON-state current, low OFF-state leakage current, minimal current collapse, and enhanced thermal power dissipation capability at the same time, which can directly be correlated with the absence of high dislocation density.},
	year = {2018},
	eissn = {1557-9646},
	pages = {2939-2947},
	orcid-numbers = {Tóth, Lajos/0000-0003-0334-2869; Pécz, Béla/0000-0002-4651-6972}
}

@article{MTMT:3400962,
	title = {Ga metal nanoparticle-GaAs quantum molecule complexes for terahertz generation},
	url = {https://m2.mtmt.hu/api/publication/3400962},
	author = {Bietti, S and Basset, FB and Scarpellini, D and Fedorov, A and Ballabio, A and Esposito, L and Elborg, M and Kuroda, T and Nemcsics, Ákos and Tóth, Lajos and Manzoni, C and Vozzi, C and Sanguinetti, S},
	doi = {10.1088/1361-6528/aacd20},
	journal-iso = {NANOTECHNOLOGY},
	journal = {NANOTECHNOLOGY},
	volume = {29},
	unique-id = {3400962},
	issn = {0957-4484},
	year = {2018},
	eissn = {1361-6528},
	orcid-numbers = {Tóth, Lajos/0000-0003-0334-2869}
}

@article{MTMT:27519782,
	title = {Droplet Epitaxy and its Possibilities in Nano-electronics},
	url = {https://m2.mtmt.hu/api/publication/27519782},
	author = {Nemcsics, Ákos and Ürmös, Antal and Tóth, Lajos},
	doi = {10.1109/ISNE.2018.8394694},
	journal-iso = {International Symposium on Next-Generation Electronics},
	journal = {International Symposium on Next-Generation Electronics},
	volume = {2018},
	unique-id = {27519782},
	issn = {2378-8593},
	year = {2018},
	pages = {122-124},
	orcid-numbers = {Nemcsics, Ákos/0000-0001-5620-3913; Ürmös, Antal/0000-0001-5620-3913; Tóth, Lajos/0000-0003-0334-2869}
}

@article{MTMT:3254420,
	title = {Investigation of ‘surface donors’ in Al2O3/AlGaN/GaN metal-oxide-semiconductor heterostructures: Correlation of electrical, structural, and chemical properties},
	url = {https://m2.mtmt.hu/api/publication/3254420},
	author = {Ťapajna, M and Stoklas, R and Gregušová, D and Gucmann, F and Hušeková, K and Haščík, Š and Fröhlich, K and Tóth, Lajos and Pécz, Béla and Brunner, F and Kuzmík, J},
	doi = {10.1016/j.apsusc.2017.07.195},
	journal-iso = {APPL SURF SCI},
	journal = {APPLIED SURFACE SCIENCE},
	volume = {426},
	unique-id = {3254420},
	issn = {0169-4332},
	abstract = {III-N surface polarization compensating charge referred here to as ‘surface donors’ (SD) was analyzed in Al2O3/AlGaN/GaN metal-oxide-semiconductor (MOS) heterojunctions using scaled oxide films grown by metal-organic chemical vapor deposition at 600 °C. We systematically investigated impact of HCl pre-treatment prior to oxide deposition and post-deposition annealing (PDA) at 700 °C. SD density was reduced down to 1.9 × 1013 cm−2 by skipping HCl pre-treatment step as compared to 3.3 × 1013 cm−2 for structures with HCl pre-treatment followed by PDA. The nature and origin of SD was then analyzed based on the correlation between electrical, micro-structural, and chemical properties of the Al2O3/GaN interfaces with different SD density (NSD). From the comparison between distributions of interface traps of MOS heterojunction with different NSD, it is demonstrated that SD cannot be attributed to interface trapped charge. Instead, variation in the integrity of the GaOx interlayer confirmed by X-ray photoelectron spectroscopy is well correlated with NSD, indicating SD may be formed by border traps at the Al2O3/GaOx interface. © 2017 Elsevier B.V.},
	keywords = {METALS; DEPOSITION; CHEMICAL PROPERTIES; interface states; chemical analysis; Heterojunctions; X ray photoelectron spectroscopy; Gallium alloys; TRANSISTORS; Organometallics; Aluminum alloys; Organic Chemicals; Metallic Compounds; MOS devices; Dielectric devices; Vapor deposition; Metallorganic chemical vapor deposition; Oxide films; Micro-structural; AlGaN/GaN; Surface polarizations; Post deposition annealing; Oxide deposition; Metal oxide semiconductor; Interface trapped charges; Oxide semiconductors; Surface donors; MOS-HEMT},
	year = {2017},
	eissn = {1873-5584},
	pages = {656-661},
	orcid-numbers = {Tóth, Lajos/0000-0003-0334-2869; Pécz, Béla/0000-0002-4651-6972}
}

@article{MTMT:3161397,
	title = {Low-temperature atomic layer deposition-grown Al2O3 gate dielectric for GaN/AlGaN/ GaN MOS HEMTs: Impact of deposition conditions on interface state density},
	url = {https://m2.mtmt.hu/api/publication/3161397},
	author = {Ťapajna, Milan and Válik, Lukáš and Gucmann, Filip and Gregušová, Dagmar and Fröhlich, Karol and Haščík, Štefan and Dobročka, Edmund and Tóth, Lajos and Pécz, Béla and Kuzmík, Ján},
	doi = {10.1116/1.4972870},
	journal-iso = {J VAC SCI TECHNOL B},
	journal = {JOURNAL OF VACUUM SCIENCE AND TECHNOLOGY B-NANOTECHNOLOGY AND MICROELECTRONICS},
	volume = {35},
	unique-id = {3161397},
	issn = {2166-2746},
	year = {2017},
	eissn = {2166-2754},
	orcid-numbers = {Tóth, Lajos/0000-0003-0334-2869; Pécz, Béla/0000-0002-4651-6972}
}