| 1. |
- Dahlquist, Fanny, et al.
(author)
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Junction barrier Schottky diodes in 4H-SiC and 6H-SiC
- 1998
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In: Materials Science Forum. - : Trans Tech Publications Inc.. - 0255-5476 .- 1662-9752. ; 264-268:PART 2, s. 1061-1064
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Journal article (peer-reviewed)abstract
- The Junction Barrier Schottky (JBS) diode in silicon carbide is a promising candidate for a low-leakage power rectifier for high switching frequencies and elevated temperature operation. It has the advantage of a low forward voltage drop while keeping a low leakage current at high blocking voltage. JBS devices have been fabricated in 4H SiC and 6H SiC and then electrically characterised in comparison with pn and Schottky diodes on the same wafer. The JBS devices reached blocking voltages up to 1.0 kV at a leakage current density of 13 ÎŒA/cm2 and the forward conduction was limited by an on-resistance close to the theoretical value.
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| 2. |
- Danielsson, Erik, et al.
(author)
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Thermal stability of sputtered TiN as metal gate on 4H-SiC
- 1998
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In: Materials Science Forum. - : Trans Tech Publications Inc.. - 0255-5476 .- 1662-9752. ; 264-268:PART 2, s. 805-808
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Journal article (peer-reviewed)abstract
- MOS-structures were made with TiN as metal gate on 4H-SiC. The thermal stability and electrical properties of this gate was determined by CV-measurements. Comparison with Al gates showed that TiN worked well as a gate metal on 4H-SiC. The hysteresis and density of the interface states were comparable for the two gate types. The n-type samples had low leakage and a flatband voltage of a few volts, while the p-type samples had high leakage and a fiatband voltage of around -20 V. The structure showed poor characteristics after a 700°C anneal for one hour, which is probably caused by the formation of titanium silicide. The TiN films had a lower content of nitrogen than expected, which could influence the stability.
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| 3. |
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| 4. |
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| 5. |
- Zetterling, Carl-Mikael, et al.
(author)
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Comparison of SiO2 and AlN as gate dielectric for SiC MOS structures
- 1998
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In: Materials Science Forum. - : Trans Tech Publications Inc.. - 0255-5476 .- 1662-9752. ; 264-268, s. 877-880
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Journal article (peer-reviewed)abstract
- The electrical properties of silicon dioxide (thermal oxidation) and aluminum nitride (metal organic chemical vapor deposition) have been compared for use as gate dielectric for silicon carbide metal insulator semiconductor structures. High frequency capacitance voltage measurements at room temperature were used to investigate fixed charge and deep interface states. The deep interface states could be passivated with hydrogen if introduced during growth of silicon dioxide. Although results are promising for aluminum nitride, the morphology of the films grown so far do not allow a fair comparison with silicon dioxide.
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| 6. |
- Edvardsson, Sverker, et al.
(author)
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The use of CI calculated polarizabilities to study rare-earth CFP dependencies in the laser host RE:YLF
- 1999
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In: Materials Science Forum. - 0255-5476. ; 315/317, s. 407-414
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Journal article (peer-reviewed)abstract
- It has earlier been shown that the Sternheimer method is appropriate in deriving crystal field parameters (CFP) for Pr3+ and Nd3+ doped in YLF or Nd3+ in YAG. In this connection, the dipole (αD) and quadrupole (αQ) polarizabilities for the whole rare-earth (RE) series will be presented. These are needed for the self consistent lattice summations performed. The various rare-earth wavefunctions needed for the computations are derived from the well known relativistic full Hartree-Fock code by R. D. Cowan. The main CFP behaviour for the various RE dopants in YLF are seen to agree fairly well with the experimentally fitted parameters. Covalency effects are, as expected, observed to be more important for higher order parameters. It is also seen that the contribution to the crystal field due to covalency is approximately constant for a given Btp. This observation is also supported by calculations of Newman. The shielding, nuclear antishielding factors and radial integrals for the whole RE series are also presented.
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| 7. |
- Klintenberg, Mattias, et al.
(author)
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The use of molecular dynamics to simulate the temperature dependence of the calculated absorption spectrum for Nd3+:YAG
- 1999
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In: Materials Science Forum. - 0255-5476. ; 315-317, s. 42-50
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Journal article (peer-reviewed)abstract
- The use of molecular dynamics (MD) and the inclusion of configuration interaction (CI) effects have been shown to be important in the simulation of polarized absorption spectra for rare-earth doped compounds. This work, focuses on how well the MD approach can account for the temperature dependence of the calculated absorption spectrum for Nd3+:YAG, using the standard MD pair-potential of the Born-Mayer-Huggins form. All simulated spectra are compared to the corresponding experimental spectra. The results indicate that the simple pair-potential must be replaced by a many-body potential to describe the motion of the ions with sufficient accuracy. They also suggest that an “effective temperature” (T') should be used in the MD simulation of the form T'=aT+b
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| 8. |
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