Papers by Author: Bengt Gunnar Svensson

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Authors: Lars S. Løvlie, Lasse Vines, Bengt Gunnar Svensson
Abstract: 4H-SiC has been irradiated with 10 keV protons and a laterally resolved DLTS study performed to study the diffusion of irradiation induced intrinsic point defects. It is found that the defects migrate on the order of hundreds of μm laterally and carbon interstitials (CI) are believed to be involved in the defect formation. However, the vertical diffusion lengths are revealed to be several orders of magnitude shorter, on the order of hundreds of nm. Specifically, the Z1,2, S1,2 and EH6,7 levels are found to be generated significant distances from the irradiated area, suggesting that CI or another highly mobile species are involved in the formation of these defects.
Authors: J. Lennart Lindström, Bengt Gunnar Svensson, W.M. Chen
Authors: Ioana Pintilie, Francesco Moscatelli, Roberta Nipoti, Antonella Poggi, Sandro Solmi, Bengt Gunnar Svensson
Abstract: This work is focusing on the effect of a high concentration of nitrogen (N) introduced by ion implantation at the SiO2/4H-SiC interface in MOS capacitors. The N implanted sample (Ninterface ~1x1019cm-3) is compared with a non-implanted one (Ninterface ~1x1016cm-3) by means of the electron interface trap density (Dit). The Dit is determined via High-Low frequency C-V method and Thermal Dielectric Relaxation Current (TDRC) technique. It is shown that the TDRC method, mainly used so far for determination of near interface oxide charges, can be exploited to gain information about the Dit too. The determined value of Dit in the N-implanted sample is nearly one order of magnitude lower than that in the sample without N implantation. Good agreement between the TDRC results and those obtained from High-Low frequency C-V measurements is obtained. Furthermore, the TDRC method shows a high accuracy and resolution of Dit evaluation in the region close to the majority carrier band edge and gives information about the traps located into the oxide.
Authors: T. Hallberg, J. Lennart Lindström, Bengt Gunnar Svensson, Krzysztof Swiatek
Authors: Bengt Gunnar Svensson, J. Lennart Lindström
Authors: Margareta K. Linnarsson, Martin S. Janson, Adolf Schöner, Andrey O. Konstantinov, Bengt Gunnar Svensson
Authors: Quan Bao Ma, Augustinas Galeckas, Alexander Azarov, Annett Thøgersen, Patricia Almeida Carvalho, Daniel N. Wright, Spyros Diplas, Ole Martin Løvvik, Valdas Jokubavicius, Xin Yu Liu, Jian Wu Sun, Mikael Syväjärvi, Bengt Gunnar Svensson
Abstract: Sublimation-grown 3C-SiC crystals were implanted with 2 atomic percent of boron ions at elevated temperature (400 °C) using multiple energies (100 to 575 keV) with a total dose of 8.5×1016 atoms/cm2. The samples were then annealed at 1400, 1500 and 1600 °C for 1h at each temperature. The buried boron box-like concentration profile can reach ~2×1021 cm-3 in the plateau region. The optical activity of the incorporated boron atoms was deduced from the evolution in absorption and emission spectra, indicating possible pathway for achieving an intermediate band behavior in boron doped 3C-SiC at sufficiently high dopant concentrations.
Authors: Mads E. Ingebrigtsen, Lasse Vines, Giovanni Alfieri, Andrei Mihaila, Uwe Badstübner, Bengt Gunnar Svensson, Andrej Kuznetsov
Abstract: Electrical properties of Schottky contacts of high work-function metals (Pd, Au, and Ni) on (010) and (201) oriented β-Ga2O3 were investigated. Current-voltage characteristics reveal that all the contacts exhibit high rectifying behavior with ideality factors as low as 1.04. However, the reverse leakage currents were lower in the (010) samples compared to the (201) ones. Thermal admittance spectroscopy confirms a main charge carrier level to be at ~0.15 eV below the conduction band edge (Ec). Secondary ion mass spectrometry indicates that Si may be responsible for this donor level. Deep level transient spectroscopy reveals four levels (E1-E4) in the upper part of the band gap, with the corresponding energy level positions at 0.56, 0.76, 1.01, and 1.48 eV below Ec.
Authors: Valentin V. Litvinov, Bengt Gunnar Svensson, L.I. Murin, J. Lennart Lindström, Vladimir P. Markevich
Abstract: Intensities of infrared absorption due to asymmetric stretching vibrations of interstitial oxygen atoms in Ge crystals enriched with 16O and 18O isotopes have been compared with oxygen concentrations determined by means of secondary ion mass spectrometry (SIMS). For Ge samples with oxygen content less than 5⋅1017 cm-3 a good correlation has been found between the values of oxygen concentration and values of absorption coefficient in maximum of the absorption band at 855.6 cm-1 with a proportionality coefficient CO = 0.95.1017 сm-2. It is argued that kinetics of oxygen-related thermal double donor formation and oxygen loss upon heat-treatments of Ge crystals at 350 оС cannot be described properly with the application of calibration coefficient CO = 5.1016 cm-2, which is widely used for the determination of oxygen concentration in Ge crystals.
Authors: Giovanni Alfieri, Edouard V. Monakhov, Margareta K. Linnarsson, Bengt Gunnar Svensson
Abstract: Deep level transient spectroscopy (DLTS) was employed to investigate the annealing behaviour and thermal stability of radiation induced defects in nitrogen doped 4H-SiC epitaxial layers, grown by chemical vapor deposition (CVD). The epilayers have been irradiated with 15 MeV electrons and an isochronal annealing series has been carried out. The measurements have been performed after each annealing step and six electron traps located in the energy band gap range of 0.42-1.6 eV below the conduction band edge (Ec) have been detected.
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