| 1. |
- Ber, B. Y., et al.
(författare)
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Determination of nitrogen in silicon carbide by secondary ion mass spectrometry
- 2004
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Ingår i: Journal of Analytical Chemistry. - 1061-9348 .- 1608-3199. ; 59:3, s. 250-254
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Tidskriftsartikel (refereegranskat)abstract
- The emission of atomic and complex nitrogen ions, which are the main impurity determining the n type conduction of silicon carbide, is investigated. It is shown that, among all the secondary ions of the CxN and SixN kind (x = 0, 1, 2, 3), the (26)(CN)(-) fragment exhibits the highest ion yield. The use of an ion peak with a specified mass as an analytical signal provides a detection limit for nitrogen in SiC at a level of 10(16) cm(-3). This result is attained in measurements at high mass resolution (M/DeltaM = 7500, interference peak (26)(C-13(2))(-)).
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| 2. |
- Blank, T. V., et al.
(författare)
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Temperature dependence of the quantum efficiency of 4H-SiC-Based Schottky photodiodes
- 2001
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Ingår i: Technical physics letters. - : Pleiades Publishing Ltd. - 1063-7850 .- 1090-6533. ; 27:9, s. 776-778
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Tidskriftsartikel (refereegranskat)abstract
- Using metal-semiconductor structures based on a pure epitaxial layer of n-4H-SiC (N-d - N-a = 4 x 10(15) cm(-3)), UV photodetectors were created with a maximum photosensitivity at 4.9 eV and a quantum efficiency up to 0.3 el/ph. The photosensitivity spectrum of the base structure is close to the spectrum of bactericidal action of the UV radiation. For photon energies in the 3.4 - 4.7 eV range, the quantum efficiency of the photoelectric conversion exhibits rapid growth with the temperature above 300 K, which is explained by the participation of photons in indirect interband transitions. This growth is not manifested when the photon energy is close to the threshold energy of direct optical transitions in the nondirect-bandgap semiconductor, which allows the threshold energy to be evaluated (similar to4.9 eV).
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| 3. |
- Bratus, V. Y., et al.
(författare)
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Vacancy-related defects in ion-beam and electron irradiated 6H-SiC
- 2001
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Ingår i: Applied Surface Science. - 0169-4332 .- 1873-5584. ; 184:04-jan, s. 229-236
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Tidskriftsartikel (refereegranskat)abstract
- A brief review is given on EPR study of irradiation-induced defects in SiC. The results of low-temperature study of Ky1 and Ky2 centers reveal for both of them the C-S symmetry, spin S = 1/2 and close coincidence of the g-tensor components. For Ky2 defect the principal values of g-tensor have been determined as g(z) = 2.0048, g(x) = 2.0022 and g(y) = 2.0037, where z and x directions reside in the (11 (2) over bar0) plane and the z-axis makes up an angle 65 degrees with the c-axis. The same residence of z- and x-axis and an angle 59 degrees are found for Ky1 center, g(z) = 2.0058, g(x) = 2.0025 and g(y) = 2.0023. A comparison of experimental and calculated hyperfine (HF) parameters is presented which suggests that Ky2 and Ky1 defects can be assigned to the positively charged carbon vacancy in 6H-SiC. The EPR study of defects created along the Al+ ion track in n-type 6H-SiC shows that lineshape, linewidth and integral intensity of the EPR signal reflect the state of damaged layer generated by ion implantation. A variation of defect density with annealing is reported and defect origin is discussed.
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| 4. |
- Ivanov, A M, et al.
(författare)
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High-resolution short range ion detectors based on 4H-SiC films
- 2004
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Ingår i: Technical physics letters. - : Pleiades Publishing Ltd. - 1063-7850 .- 1090-6533. ; 30:7, s. 575-577
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Tidskriftsartikel (refereegranskat)abstract
- The energy resolution of SiC detectors has been studied in application to the spectrometry of alpha particles with 5.1-5.5 MeV energies. The Schottky barrier structure of the detector was based on a CVD-grown epitaxial n-4H-SiC film with a thickness of 26 mum and an uncompensated donor concentration of (1-2) x 10(15) cm(-3). An energy resolution of 0.5% achieved for the first time with SiC detectors allows fine structure of the alpha particle spectrum to be revealed. The average energy of the electron-hole pair formation in 4H-SiC is estimated at 7.71 eV.
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| 5. |
- Kalinina, E., et al.
(författare)
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Characterization of Al-implanted 4H SiC high voltage diodes
- 2002
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Ingår i: Physica Scripta. - 0031-8949 .- 1402-4896. ; T101, s. 207-210
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Tidskriftsartikel (refereegranskat)abstract
- The properties of 4H-SiC chemical vapor deposition epitaxial layers were studied by different methods. The effects of structural defects in 4H-SiC epitaxial layers on electrical and luminescence properties of Al high dose ion implanted p(+)-n junctions were studied. It has been shown that the structural imperfections of low-doped layers affect some electrical characteristics of the ion doped p(+)-n junctions created in these epitaxial layers.
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| 6. |
- Kalinina, E., et al.
(författare)
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Electrical study of fast neutron irradiated devices based on 4H-SiC CVD epitaxial layers
- 2004
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Ingår i: SILICON CARBIDE AND RELATED MATERIALS 2003, PRTS 1 AND 2. ; , s. 705-708
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Konferensbidrag (refereegranskat)abstract
- The radiation-induced defect formation in high purity 4H-SiC CVD epitaxial layers and changes in the electrical properties of diode structures based on its after irradiation with different fluences I MeV neutrons were investigated at temperatures as high as 700 K. The Z(1), deep center, typical for 4H-SiC, was observed both in the initial and irradiated samples. The presence and number of different deep levels increased with the neutron fluence. The rectifying properties of the diode structures disappeared after neutron irradiation with fluence of 6.2x10(14) cm(-2). However, the diode structures that had been degraded after irradiation with fast neutrons, recovered their properties at the temperature of 700 K.
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| 7. |
- Kalinina, E., et al.
(författare)
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High-dose Al-implanted 4H-SiC p(+)-n-n(+) junctions
- 2000
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Ingår i: Applied Physics Letters. - : AIP Publishing. - 0003-6951 .- 1077-3118. ; 77:19, s. 3051-3053
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Tidskriftsartikel (refereegranskat)abstract
- p(+)-n-n(+) junctions were fabricated by ion implantation with Al of low-doped epitaxial n layers of 4H-SiC grown by chemical vapor deposition on commercial 4H-SiC wafers both with and without reduction of micropipe densities. It was shown that, using high levels of Al ion doping (5x10(16) cm(-2)) in combination with rapid thermal anneal, single-crystal p(+)-4H-SiC layers can be obtained. These layers do not form barriers at the contact metal-semiconductor interface and do not introduce additional resistance into structures with p(+)-n junctions. This significantly reduces the forward voltage drop across the structure in a wide range of current densities up to 10(4) A cm(-2).
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| 8. |
- Kalinina, E., et al.
(författare)
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Influence of ion implantation on the quality of 4H-SiC CVD epitaxial layers
- 2001
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Ingår i: Applied Surface Science. - 0169-4332 .- 1873-5584. ; 184:04-jan, s. 323-329
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Tidskriftsartikel (refereegranskat)abstract
- The effect of ion implantation doping (ID) with high doses of Al followed by short high-temperature annealing of n-type 4H-SiC epitaxial layers grown by chemical vapor deposition (CVD) has been studied. The comparative investigations of the structural and electrical properties, lateral and as a function of depth, in the CVD layers before and after Al ID p(+)n junction formations were determined by several different methods. Structural improvement of the CVD epitaxial layers close to Al ID p(+)n junction positions was revealed for the first time.
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| 9. |
- Kalinina, E., et al.
(författare)
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Material quality improvements for high voltage 4H-SiC diodes
- 2001
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Ingår i: Materials Science & Engineering. - 0921-5107 .- 1873-4944. ; 80:03-jan, s. 337-341
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Tidskriftsartikel (refereegranskat)abstract
- The influence of thin 4H-SiC buffer layers grown by liquid phase epitaxy (LPE) on structural quality of 4H-SiC low-doped epitaxial layers, grown by chemical vapor deposition (CVD) was investigated in detail. A dramatic defect density reduction in CVD epitaxial layers grown on commercial wafers with buffer LPE layer was detected. P(+)n junctions were formed on these CVD layers by high dose Al ion implantation followed by rapid thermal anneal. It was shown that both the increase of diffusion lengths of minority carriers (Lp) in CVD lavers and the forming of p(+)-layers after Al ion implantation and high temperature anneal lead to superior device characteristics.
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| 10. |
- Kalinina, E., et al.
(författare)
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Structural, electrical, and optical properties of low-doped 4H-SiC chemical vapor deposited epitaxial layers
- 2001
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Ingår i: Journal of Applied Physics. - : AIP Publishing. - 0021-8979 .- 1089-7550. ; 90:10, s. 5402-5409
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Tidskriftsartikel (refereegranskat)abstract
- Results of complex studies of structural, optical, and electrical characteristics of 4H-SiC n-type low-doped epitaxial layers grown by the chemical vapor deposition (CVD) method are presented. Characteristics of CVD layers grown on commercial wafers with and without a thin (<0.1 mum) buffer layer grown by liquid phase epitaxy (LPE) between the commercial wafer and CVD epitaxial layer were compared. It has been shown that the LPE filling process caused a significant improvement in the structural quality of CVD layers. Cathodoluminescence (CL) data and electrical characteristics of Schottky barriers (SB) revealed that the LPE layer also made the concentration profiles of the uncompensated donors and recombination centers for holes as well as the hole diffusion lengths more uniform over the CVD layer. According to CL and secondary ion mass-spectroscopy measurements the presence of aluminum as an impurity was detected in initial commercial wafers, as well as having LPE and CVD epitaxial layers. Forward current-voltage characteristics of SBs formed on CVD layers with and without a LPE buffer layer followed an exponential relationship with an ideality factor of 1.04-1.06 over six to seven orders of magnitude in current density. A noticeable increase of the breakdown voltage was also observed in samples with a LPE layer.
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