Zobrazeno 1 - 10
of 42
pro vyhledávání: '"Roman Dimitrov"'
Autor:
Martin Stutzmann, T. Graf, Oliver Ambacher, James S. Speck, Y. Smorchkova, Roman Dimitrov, A. Link, Umesh K. Mishra
Publikováno v:
physica status solidi (b). 228:603-606
We have performed Shubnikov-de Haas (SdH) and Hall effect measurements to investigate the electronic transport properties of polarisation induced 2DEGs in Al x Ga 1-x N/GaN heterostructures with alloy compositions between x = 0.10 and 0.35 and sheet
Autor:
Oliver Ambacher, Roman Dimitrov, William J. Schaff, T. Prunty, Joseph A. Smart, E.M. Chumbes, Hyungtak Kim, M. J. Murphy, L.F. Eastman, Nils Weimann, V. Tilak, B.M. Green, James R. Shealy
Publikováno v:
IEEE Transactions on Electron Devices. 48:479-485
Undoped AlGaN/GaN structures are used to fabricate high electron mobility transistors (HEMTs). Using the strong spontaneous and piezoelectric polarization inherent in this crystal structure a two-dimensional electron gas (2DEG) is induced. Three-dime
Autor:
Oliver Ambacher, Hyungtak Kim, B.M. Green, L.F. Eastman, Martin Stutzmann, V. Tilak, Roman Dimitrov, James R. Shealy, Joseph A. Smart, E.M. Chumbes, William J. Schaff, C. R. Miskys, W. Yeo
Publikováno v:
Solid-State Electronics. 44:1361-1365
Plasma-induced damage often reduces the electrical and optical performance and the lifetime of compound semiconductor devices. We have investigated the effect of oxygen and methane reactive ion etching plasma on the electrical characteristics of nomi
Autor:
Martin S. Brandt, M. W. Bayerl, Martin Stutzmann, Sebastian T. B. Goennenwein, Roman Dimitrov, Oliver Ambacher, R. Zeisel
Publikováno v:
Physical Review B. 61:R16283-R16286
In Si doped AlN, a large persistent photoconductivity is found for temperatures below 60 K after exposure to light with photon energies above 1.5 eV. Simultaneously, a persistent electron spin resonance signal is observed with an isotropic g factor o
Autor:
Oliver Ambacher, L.F. Eastman, Martin Stutzmann, James R. Shealy, William J. Schaff, Joseph A. Smart, Roman Dimitrov, M. J. Murphy
Publikováno v:
Scopus-Elsevier
We report on the growth of nominally undoped GaN/AlxGa1−xN/GaN (x
Autor:
A. J. Sierakowski, Roman Dimitrov, Oliver Ambacher, Nils Weimann, James R. Shealy, A. Mitchell, B. E. Foutz, William J. Schaff, M. J. Murphy, K. Chu, Joseph A. Smart, L.F. Eastman, Martin Stutzmann
Publikováno v:
Scopus-Elsevier
Two dimensional electron gases in Alcursivₑ chiGa₁₋cursivₑ chiN/GaN based heterostructures, suitable for high electron mobility transistors, are induced by strong polarization effects. The sheet carrier concentration and the confinement of th
Autor:
J. Krinke, Roman Dimitrov, Martin Albrecht, Axel Voigt, Ana Cremades, Oliver Ambacher, Martin Stutzmann
Publikováno v:
Solid State Phenomena. :139-146
Combined electron beam induced current and transmission electron microscopy measurements have been performed on both undoped and Si-doped AlGaN epitaxial films with aluminium contents x ranging from x=0 to x=0.79. TEM analysis shows the distribution
Autor:
Martin S. Brandt, Ch Deger, T. Metzger, N. M. Reinacher, Oliver Ambacher, F. Freudenberg, A. Cros, Martin Stutzmann, Roman Dimitrov, D. Brunner, R. Höpler, R. Handschuh, H. Angerer
Publikováno v:
Scopus-Elsevier
AlGaN epitaxial films have been grown on sapphire by plasma-induced molecular beam epitaxy (MBE) over the entire composition range from GaN to AlN. Structural and optical properties of the alloys have been investigated by X-ray diffraction (XRD), tra
Autor:
Roman Dimitrov, Martin Stutzmann, W. Rieger, H. Angerer, Andreas Bergmaier, Oliver Ambacher, Günther Dollinger
Publikováno v:
Scopus-Elsevier
The role of hydrogen in gallium nitride was studied on thin films of GaN on sapphire prepared at substrate temperatures in the range of 600 to 1100 °C. By using triethylgallium and ammonia as precursor and hydrogen and/or nitrogen as transport gases
Publikováno v:
Scopus-Elsevier
Sub-band-gap absorption of GaN grown by metal-organic chemical vapor deposition on sapphire was investigated by photothermal deflection spectroscopy (PDS), transmission measurements, and the constant photocurrent method (CPM). We determine acceptor b