Articles 2020

  • Delgado Carrascon, R.; Tran, D. Q.; Sukkaew, P.; Mock, A.; Ciechonski, R.; Ohlsson, J.; Zhu, Y.; Hultin, O.; Monemar, B.; Paskov, P. P.; Samuelson, L.; Darakchieva, V. Optimization of GaN Nanowires Reformation Process by Metalorganic Chemical Vapor Deposition for Device‐Quality GaN Templates. Phys. Status Solidi B 2020, 1900581. https://doi.org/10.1002/pssb.201900581.
  • Chen, D.-Y.; Malmros, A.; Thorsell, M.; Hjelmgren, H.; Kordina, O.; Chen, J.-T.; Rorsman, N. Microwave Performance of ‘Buffer-Free’ GaN-on-SiC High Electron Mobility Transistors. IEEE Electron Device Lett. 2020, 828–831. https://doi.org/10.1109/led.2020.2988074.
  • Bremer, J.; Chen, D. Y.; Malko, A.; Madel, M.; Rorsman, N.; Gunnarsson, S. E.; Andersson, K.; Nilsson, T. M. J.; Raad, P. E.; Komarov, P. L.; Sandy, T. L.; Thorsell, M. Electric-Based Thermal Characterization of GaN Technologies Affected by Trapping Effects. IEEE Trans. Electron Devices 2020, 1952–1958. https://doi.org/10.1109/ted.2020.2983277.
  • Huang, T.; Axelsson, O.; Bergsten, J.; Thorsell, M.; Rorsman, N. Impact of AlGaN/GaN Interface and Passivation on the Robustness of Low-Noise Amplifiers. IEEE Trans. Electron Devices 2020, 2297–2303. https://doi.org/10.1109/ted.2020.2986806.
  • Schubert, M.; Mock, A.; Korlacki, R.; Knight, S.; Monemar, B.; Goto, K.; Kumagai, Y.; Kuramata, A.; Galazka, Z.; Wagner, G.; Tadjer, M.; Wheeler, V.; Higashiwaki, M.; Darakchieva, V. Phonon Properties: Phonon and Free Charge Carrier Properties in Monoclinic-Symmetry -Ga2O3. In Gallium Oxide; Springer International Publishing, 2020; pp 501–534. https://doi.org/10.1007/978-3-030-37153-1_28.
  • Stokey, M.; Mock, A.; Korlacki, R.; Knight, S.; Darakchieva, V.; Shone, S.; Schubert, M. Infrared Active Phonons in Monoclinic Lutetium Oxyorthosilicate. Journal of Applied Physics 2020, 127 (11), 115702. https://doi.org/10.1063/1.5135016.
  • Tran, D. Q.; Blumenschein, N.; Mock, A.; Sukkaew, P.; Zhang, H.; Muth, J. F.; Paskova, T.; Paskov, P. P.; Darakchieva, V. Thermal Conductivity of Ultra-Wide Bandgap Thin Layers – High Al-Content AlGaN and β-Ga2O3. Physica B: Condensed Matter 2020, 579, 411810. https://doi.org/10.1016/j.physb.2019.411810.
  • Korlacki, R.; Mock, A.; Briley, C.; Darakchieva, V.; Monemar, B.; Kumagai, Y.; Goto, K.; Higashiwaki, M.; Schubert, M. Comment on “Characteristics of Multi-Photon Absorption in a β-Ga2O3 Single Crystal” [J. Phys. Soc. Jpn. 88, 113701 (2019)]. J. Phys. Soc. Jpn. 2020, 89, 036001. https://doi.org/10.7566/jpsj.89.036001.
  • Zhang, H.; Paskov, P. P.; Kordina, O.; Chen, J.-T.; Darakchieva, V. N-Polar AlN Nucleation Layers Grown by Hot-Wall MOCVD on SiC: Effects of Substrate Orientation on the Polarity, Surface Morphology and Crystal Quality. Physica B: Condensed Matter 2020, 580, 411819. https://doi.org/10.1016/j.physb.2019.411819.
  • Tran D. Q.; Carrascon R. D.; Muth J. F.; Paskova T.; Nawaz M.; Darakchieva V.; P.P. Paskov, V. Boundary scattering and phonon transport in AlGaN: Effect of layer thickness. Applied Physics Letters 2020, 117, 252102. https://doi.org/10.1063/5.0031404.
  • Gopalan P.; Knight S.; Chanana A.; Stokey M.; Ranga P.; Scarpulla M. A.; Krishnamoorthy S.; Darakchieva V.; Galazka Z.; Irmscher K.; Fiedler A.; Blair S.; Schubert M.; Sensale-Rodriguez B. The anisotropic quasi-static permittivity of single crystal β-Ga2O3. Applied Physics Letters 2020, 117, 252103. https://doi.org/10.1063/5.0031464.
  • Korlacki R.; Stokey M.; Knight S.; Papamichail A.; Darakchieva V.; Schubert M. Strain and stress relationships for optical phonon modes in monoclinic crystals with β-Ga2O3 as an example. Physical Review B 2020, 102, 180101. https://link.aps.org/doi/10.1103/PhysRevB.102.180101.
  • Knight S.; Schöche S.; Kühne P.; Hoffman T.; Darakchieva V.; Schubert M. Tunable cavity-enhanced terahertz frequency- domain optical Hall effect. Review of Scientific Instruments 2020 91, 083903. https://doi.org/10.1063/5.0010267.
  • Stokey M.; Korlacki R.; Knight S.; Hilfiker M.; Galazka Z.; Irmscher K.; Darakchieva V.; Schubert M. Brillouin zone center phonon modes in ZnGa2O4. Applied Physics Letters 2020 117, 052104. https://doi.org/10.1063/5.0012526.

Articles 2019

  • Lu, J.; Chen, J.-T.; Dahlqvist, M.; Kabouche, R.; Medjdoub, F.; Rosen, J.; Kordina, O.; Hultman, L. Transmorphic Epitaxial Growth of AlN Nucleation Layers on SiC Substrates for High-Breakdown Thin GaN Transistors. Appl. Phys. Lett. 2019, 115 (22), 221601. https://doi.org/10.1063/1.5123374.
  • Huang, T.; An, S.; Bergsten, J.; He, S.; Rorsman, N. A Power Detector Based on GaN High-Electron-Mobility Transistors for a Gigabit on–off Keying Demodulator at 90 GHz. Jpn. J. Appl. Phys. 2019, 58, SCCD19. https://doi.org/10.7567/1347-4065/ab09d9.
  • Hilfiker, M.; Kilic, U.; Mock, A.; Darakchieva, V.; Knight, S.; Korlacki, R.; Mauze, A.; Zhang, Y.; Speck, J.; Schubert, M. Dielectric Function Tensor (1.5 EV to 9.0 EV), Anisotropy, and Band to Band Transitions of Monoclinic β-(AlxGa1–x)2O3 (x ≤ 0.21) Films. Appl. Phys. Lett. 2019, 114 (23), 231901. https://doi.org/10.1063/1.5097780.
  • Malmros, A.; Gamarra, P.; Thorsell, M.; Hjelmgren, H.; Lacam, C.; Delage, S. L.; Zirath, H.; Rorsman, N. Impact of Channel Thickness on the Large-Signal Performance in InAlGaN/AlN/GaN HEMTs With an AlGaN Back Barrier. IEEE Trans. Electron Devices 2019, 364–371. https://doi.org/10.1109/ted.2018.2881319.
  • Malmros, A.; Chen, J.-T.; Hjelmgren, H.; Lu, J.; Hultman, L.; Kordina, O.; Sveinbjornsson, E. O.; Zirath, H.; Rorsman, N. Enhanced Mobility in InAlN/AlN/GaN HEMTs Using a GaN Interlayer. IEEE Trans. Electron Devices 2019, 2910–2915. https://doi.org/10.1109/ted.2019.2914674.
  • Schubert, M.; Mock, A.; Korlacki, R.; Knight, S.; Galazka, Z.; Wagner, G.; Wheeler, V.; Tadjer, M.; Goto, K.; Darakchieva, V. Longitudinal Phonon Plasmon Mode Coupling in β-Ga2O3. Appl. Phys. Lett. 2019, 102102. https://doi.org/10.1063/1.5089145.
  • Eriksson, M. O.; Khromov, S.; Paskov, P. P.; Wang, X.; Yoshikawa, A.; Holtz, P. O.; Monemar, B.; Darakchieva, V. Recombination Processes in Mg Doped Wurtzite InN Films with P- and n-Type Conductivity. AIP Advances 2019, 015114. https://doi.org/10.1063/1.5052432.
  • Schubert, M.; Mock, A.; Korlacki, R.; Darakchieva, V. Phonon Order and Reststrahlen Bands of Polar Vibrations in Crystals with Monoclinic Symmetry. Phys. Rev. B 2019, 99 (4), 041201. https://doi.org/10.1103/PhysRevB.99.041201.
  • Mock, A.; Korlacki, R.; Knight, S.; Stokey, M.; Fritz, A.; Darakchieva, V.; Schubert, M. Lattice Dynamics of Orthorhombic  NdGaO3. Phys. Rev. B 2019, 99 (18). https://doi.org/10.1103/physrevb.99.184302.

Articles 2018

  • Huang, T.; Jiang, H.; Bergsten, J.; Lau, K. M.; Rorsman, N. Enhanced Gate Stack Stability in GaN Transistors with Gate Dielectric of Bilayer SiNx by Low Pressure Chemical Vapor Deposition. Appl. Phys. Lett. 2018, 232102. https://doi.org/10.1063/1.5042809.
  • Armakavicius, N.; Stanishev, V.; Knight, S.; Kühne, P.; Schubert, M.; Darakchieva, V. Electron Effective Mass in In0.33Ga0.67N Determined by Mid-Infrared Optical Hall Effect. Appl. Phys. Lett. 2018, 082103. https://doi.org/10.1063/1.5018247.
  • Kuhne, P.; Armakavicius, N.; Stanishev, V.; Herzinger, C. M.; Schubert, M.; Darakchieva, V. Advanced Terahertz Frequency-Domain Ellipsometry Instrumentation for In Situ and Ex Situ Applications. IEEE Trans. THz Sci. Technol. 2018, 257–270. https://doi.org/10.1109/tthz.2018.2814347.
  • Lin, Y.-K.; Bergsten, J.; Leong, H.; Malmros, A.; Chen, J.-T.; Chen, D.-Y.; Kordina, O.; Zirath, H.; Chang, E. Y.; Rorsman, N. A Versatile Low-Resistance Ohmic Contact Process with Ohmic Recess and Low-Temperature Annealing for GaN HEMTs. Semicond. Sci. Technol. 2018, 095019. https://doi.org/10.1088/1361-6641/aad7a8.
  • Chen, J.-T.; Bergsten, J.; Lu, J.; Janzén, E.; Thorsell, M.; Hultman, L.; Rorsman, N.; Kordina, O. A GaN–SiC Hybrid Material for High-Frequency and Power Electronics. Appl. Phys. Lett. 2018, 041605. https://doi.org/10.1063/1.5042049.
  • Bergsten, J.; Thorsell, M.; Adolph, D.; Chen, J.-T.; Kordina, O.; Sveinbjornsson, E. O.; Rorsman, N. Electron Trapping in Extended Defects in Microwave AlGaN/GaN HEMTs With Carbon-Doped Buffers. IEEE Trans. Electron Devices 2018, 2446–2453. https://doi.org/10.1109/ted.2018.2828410.

DOCTORAL THESIS

  1. Malmros,N. Advanced III-Nitride Technology for mm-Wave Applications, Doktorsavhandlingar vid Chalmers tekniska högskola. Ny serie: 4594 , 2019.
  2. https://research.chalmers.se/en/publication/510091.
  3. Armakavicius, N. Free Charge Carrier Properties in Group III Nitrides and Graphene Studied by THz-to-MIR Ellipsometry and Optical Hall Effect. Linköping Studies in Science and Technology. Dissertations, 2019. https://doi.org/10.3384/diss.diva-154921.
  4. Bergsten, J. Buffer Related Dispersive Effects in Microwave GaN HEMTs, Calmers University of Technology: Chalmers, Sweden, 2018.
  5. research.chalmers.se/publication/501617

LICENTIATE THESES

  • Ding Yuan Chen, Optimization of Ohmic Contacts and Surface Passivation for “Buffer-Free” GaN HEMT Technologies, Chalmers University and SweGaN

  • Dat Tran, Thermal conductivity of AlxGa1-xN and β-Ga2O3 semiconductors, Linköping University

MASTER THESIS

  • Ohlsson, K. Optimization of Uniformity in Enhancement of Metal Organic Chemical Vapor Deposition Growth, Linköping University: Linköping

  • Kai-Hsin Wen, Study of ohmic contact formation on AlGaN/GaN heterostructures, Chalmers University of Technology and KTH

  • Oscar Johansson, Transition Time Impairment of GaN Switches in Electromagnetic Harsh Environments, Chalmers University of Technology and Saab

  • Emil Bjärehäll, Power System-on-Chip for Future Airborne Sensor Systems Feasibility Analysis, Chalmers University of Technology and Saab

  • Laurenz Geihofer, Epitaxial growth and basic material characterization of β-Ga2O3, Linköping University and Graz University of Technology

Conference contributions

APWS 2019, Okinawa, Japan, November 2019

  • M. Schubert, A. Mock, R. Korlacki, S. Knight, V. Darakchieva, S. Galazka, G. Wagner, H. Murakami, Y. Kumagai, K. Goto, M. Higashiwaki, and J. Speck. Phonons, free charge carriers, excitons and band-to-band transitions in β Ga2O3 and related alloys determined by ellipsometry and optical Hall effect (Invited talk)

8th international conference on spectroscopic ellipsometry, ICSE-8, Barcelona, Spain 2019

  • N. Armakavicius, P. Kuehne, V. Stanishev, S. Knight, T. Hofmann, C.M., Herzinger, M. Schubert, and V. Darakchieva “Stealth Technology-Based Terahertz Frequency-Domain Ellipsometry for In-situ and Ex-situ Applications” (Invited talk)
  • P. Kuehne, N. Armakavicius, V. Stanishev, Jr-Tai Chen, O. Kordina, M. Schubert, and V. Darakchieva “Field- and temperature-dependent optical Hall effect in group-III nitrides”(Talk) 
  • A. Mock, R. Korlacki, S. Knight, Z. Galazka, G. Wagner, V. Wheeler, M. Tadjer, K. Goto, and V. Darakchieva M. Schubert “Longitudinal phonon plasmon mode coupling and the strain-stress relationships in beta-Ga2O3” (Talk) 
  • A. Mock, R. Korlacki, S. Knight, M. Tadjer, V. Darakchieva, and M. Schubert “Generalized Ellipsometry on Low Symmetry Materials” (Invited talk)

13th International Conference on Nitride Semiconductors, ICNS-13, Bellevue USA,
July 2019

  • D. Y. Chen, Jr. Tai Che, O. Kordina, N. Rorsman, “QuanFINE – High RF Performance AlGaN/AlN/GaN HEMTs with a Thin Buffer Layer”

  • Rosalia Delgado-Carrascon, Dat Tran, Pitsiri Sukkaew, Alyssa Mock, Plamen P. Paskov, Rafal Ciechonski, Jonas Ohlsson, Yadan Zhu, Bo Monemar, Lars Samuelson and Vanya Darakchieva, “High quality GaN templates by coalescence overgrowth of GaN nanowires by MOCVD” (poster)

  • Dat Q. Tran, Pitsiri Sukkaew, Hengfang Zhang, Jr-Tai Chen, Motoaki Iwaya, Isamu Akasaki, Bo Monemar, Vanya Darackchieva, Plamen P. Paskov, “Thermal conductivity of AlGaN layers grown by MOCVD” (poster)

  • Hengfang Zhang, Ingemar Persson, Per Persson, Alyssa Mock, Pitsiri Sukkaew, Jr-Tai Chen and Vanya Darakchieva, “Polarity control in hot-wall MOCVD III-Nitride epitaxy on on-axis and vicinal SiC (000 ̅1) substrates” (poster)

21st International Vacuum Congress IVC-21, Malmö, Sweden, July 2019

  • Rosalia Delgado-Carrascon, Dat Tran, Pitsiri Sukkaew, Alyssa Mock, Plamen P. Paskov, Rafal Ciechonski, Jonas Ohlsson, Yadan Zhu, Bo Monemar, Lars Samuelson and Vanya Darakchieva, “High quality GaN templates by coalescence overgrowth of GaN nanowires by MOCVD” (talk)

  • Hengfang Zhang, Plamen Paskov, Olof Kordina, Jr. Tai Chen, Vanya Darakchieva “N-polar epitaxy of III Nitrides by hot wall MOCVD” (talk)

  • Olof Kordina “QuanFINE as RF and power device material” (invited)

8th South African Conference on Photonic Materials, Kariega, SA, May 2019

  • Kühne, P. Armakavicius, N. Stanishev, V. Chen, J.-T.; Kordina, O. Schubert, M. Darakchieva, V. Free Charge Carrier Properties in Group-III Nitride High Electron Mobility Transistor Structures Determined by Optical Hall Effect; Kariega, South Africa, 2019. Abstract
  • Zhang, H. Persson, I. Persson, P. Mock, A. Sukkaew, P. Chen, J.-T. Darakchieva, V. A Comprehensive Study of AlN Nucleation Layers Grown onto On-Axis and 4° off-Axis SiC (000𝟏̅) Substrates and Its Influence on GaN Growth; Kariega, South Africa, 2019. Abstract
  • Tran, D. Q. Sukkaew, P. Mock, A. Zhang, H. Blumenschein, N. Muth, John F. Paskov, P. P. Darackchieva, V. Thermal Conductivity of Ultra-Wide Bandgap Thin Layers: High-Al Content AlGaN and 𝜷-Ga2O3; Kariega, South Africa, 2019. Abstract
  • Darackchieva, V. Free charge carrier properties and phonon-plasmon coupling in ultrawide band gap semiconductors (invited talk); Kariega, South Africa, 2019.

Speck SPIE Opto Photonics West 2019, San Francisco, California, U.S.A., February 2019

  • M. Schubert, A. Mock, R. Korlacki, S. Knight, V. Darakchieva, S. Galazka, G. Wagner, H. Murakami, Y. Kumagai, K. Goto, M. Higashiwaki, and J. Speck. Phonon-plasmon coupling in monoclinic symmetry Ga2O3 (Invited talk)

10th International Workshop on Nitride Semiconductors, IWN2018, Kanazawa, Japan, November 2018

  • Sukkaew, P. Rönnby, K. Chen, J.-T. Zhang, H. Ojamäe, L. Darakchieva, V. Investigation of Growth Mode in AlN Buffer Layer for Strain and Dislocation Control in Al-Rich AlGaN Using Hot-Wall MOCVD; Kanazawa, Japan, 2018. Poster
  • Zhang, H. Persson, I. Persson, P. Mock, A. Sukkaew, P. Chen, J.-T. Darakchieva, V. Comparative Study of GaN Grown on On-Axis and Vicinal SiC (000𝟏̅) Substrates by Hot-Wall MOCVD; Kanazawa, Japan, 2018. Abstract
  • Sukkaew, P. Rönnby, K. Chen, J.-T. Zhang, H. Ojamäe, L. Darakchieva, V. Control of Growth Mode, Dislocations and Strain in Al-Rich AlGaN by Hot-Wall MOCVD; Kanazawa, Japan, 2018. Poster
  • Sukkaew, P. Chen, J.-T. Zhang, H. Darakchieva, V. The Control of Growth Mode and Strain in Al-Rich AlGaN by MOCVD; Kanazawa, Japan, 2019. Abstract

European Microwave week CSW2018, Madrid, Spain, September 2018

  • I. Angelov, “Modeling Semiconductor devices for PA” (Invited talk)

7th International Symposium on Growth of Nitride Semiconductors, ISGN-7, Warsaw, Poland, August 2018

  • Zhang, H. Sukkaew, P. Chen J.-T. and Darakchieva, V. “Hot-wall MOCVD growth of N-polar AlN nucleation layers on C-face vicinal and on-axis SiC substrates” (talk)

GaN Marathon 2.0, Padova, Italy, April 2018

  • Jr. Tai Chen ”A revolutionaryy GaN-on-SiC epitaxy for high frequency power transistors” (Invited talk)

Compound Semiconductor Week CSW2018, MIT, USA, May 2018

  • I. Angelov et al. “On the large Signal Modeling of MM wave GaAs PIN diodes” (poster)