| 1. |
- Bergman, Peder, et al.
(författare)
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Radial Variation of Measured Carrier Lifetimes in Epitaxial Layers Grown with Wafer Rotation
- 2012
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Ingår i: Materials Science Forum Vols 717 - 720. - : Trans Tech Publications Inc.. ; , s. 289-292
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Konferensbidrag (refereegranskat)abstract
- In this report we present homoepitaxial growth of 4H-SiC on the Si-face of nominally on-axis substrates with diameter up to 100 mm in a hot-wall chemical vapor deposition reactor. A comparatively low carrier lifetime has been observed in these layers. Also, local variations in carrier lifetime are different from standard off-cut epilayers. The properties of layers were studied with more focus on charge carrier lifetime and its correlation with starting growth conditions, inhomogeneous surface morphology and different growth mechanisms.
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| 2. |
- Booker, Ian Don, et al.
(författare)
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Carrier Lifetime Controlling Defects Z(1/2) and RB1 in Standard and Chlorinated Chemistry Grown 4H-SiC
- 2014
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Ingår i: Crystal Growth & Design. - : American Chemical Society (ACS). - 1528-7483 .- 1528-7505. ; 14:8, s. 4104-4110
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Tidskriftsartikel (refereegranskat)abstract
- 4H-SiC epilayers grown by standard and chlorinated chemistry were analyzed for their minority carrier lifetime and deep level recombination centers using time-resolved photoluminescence (TRPL) and standard deep level transient spectroscopy (DLTS). Next to the well-known Z(1/2) deep level a second effective lifetime killer, RB1 (activation energy 1.05 eV, electron capture cross section 2 x 10(-16) cm(2), suggested hole capture cross section (5 +/- 2) x 10(-15) cm(2)), is detected in chloride chemistry grown epilayers. Junction-DLTS and bulk recombination simulations are used to confirm the lifetime killing properties of this level. The measured RB1 concentration appears to be a function of the iron-related Fe1 level concentration, which is unintentionally introduced via the corrosion of reactor steel parts by the chlorinated chemistry. Reactor design and the growth zone temperature profile are thought to enable the formation of RB1 in the presence of iron contamination under conditions otherwise optimal for growth of material with very low Z(1/2) concentrations. The RB1 defect is either an intrinsic defect similar to RD1/2 or EH5 or a complex involving iron. Control of these corrosion issues allows the growth of material at a high growth rate and with high minority carrier lifetime based on Z(1/2) as the only bulk recombination center.
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| 3. |
- Hassan, Jawad, et al.
(författare)
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Influence of Growth Mechanism on Carrier Lifetime in on-axis Homoepitaxial Layers of 4H-SiC
- 2012
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Ingår i: Materials Science Forum Vols 717 - 720. - : Trans Tech Publications Inc.. ; , s. 157-160
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Konferensbidrag (refereegranskat)abstract
- In this report we present homoepitaxial growth of 4H-SiC on Si-face, nominally on-axis substrates with diameters up to 76 mm in a hot-wall chemical vapor deposition reactor. A comparatively low carrier lifetime has been observed in these layers; local variations in carrier lifetime are different from standard epilayers on off-cut substrates. The properties of the layers were studied with focus on charge carrier lifetime and its correlation with starting growth conditions, inhomogeneities of surface morphology and different growth mechanisms.
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| 4. |
- Kallinger, B., et al.
(författare)
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Comparison of carrier lifetime measurements and mapping in 4H SIC using time resolved photoluminescence and μ-PCD
- 2014
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Ingår i: SILICON CARBIDE AND RELATED MATERIALS 2013, PTS 1 AND 2. - Stafa-Zurich, Switzerland : Trans Tech Publications. - 9783038350101 ; , s. 301-304
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Konferensbidrag (refereegranskat)abstract
- Carrier lifetime measurements and wafer mappings have been done on several different 4H SiC epiwafers to compare two different measurement techniques, time-resolved photoluminescence and microwave induced photoconductivity decay. The absolute values of the decay time differ by a factor of two, as expected from recombination and measurement theory. Variations within each wafer are comparable with the two techniques. Both techniques are shown to be sensitive to substrate quality and distribution of extended defects.
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| 5. |
- Lilja, Louise, et al.
(författare)
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Improved Epilayer Surface Morphology on 2 degrees off-cut 4H-SiC Substrates
- 2014
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Ingår i: SILICON CARBIDE AND RELATED MATERIALS 2013, PTS 1 AND 2. - : Trans Tech Publications. ; , s. 206-209
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Konferensbidrag (refereegranskat)abstract
- Homoepitaxial layers of 4H-SiC were grown with horizontal hot-wall CVD on 2 degrees off-cut substrates, with the purpose of improving the surface morphology of the epilayers and reducing the density of surface morphological defects. In-situ etching conditions in either pure hydrogen or in a mixture of silane and hydrogen prior to the growth were compared as well as C/Si ratios in the range 0.8 to 1.0 during growth. The smoothest epilayer surface, together with lowest defect density, was achieved with growth at a C/Si ratio of 0.9 after an in-situ etching in pure hydrogen atmosphere.
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| 6. |
- Lilja, Louise, et al.
(författare)
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Influence of Growth Temperature on Carrier Lifetime in 4H-SiC Epilayers
- 2013
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Konferensbidrag (refereegranskat)abstract
- Carrier lifetime and formation of defects have been investigated as a function of growth temperature in n-type 4H-SiC epitaxial layers, grown by horizontal hot-wall CVD. Emphasis has been put on having fixed conditions except for the growth temperature, hence growth rate, doping and epilayer thickness were constant in all epilayers independent of growth temperature. An increasing growth temperature gave higher Z1/2 concentrations along with decreasing carrier lifetime. A correlation between growth temperature and D1 defect was also observed.
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| 7. |
- Lilja, Louise, et al.
(författare)
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The Effect of Growth Conditions on Carrier Lifetime in n-type 4H-SiC Epitaxial Layers
- 2012
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Ingår i: Materials Science Forum Vol 717 - 720. - : Trans Tech Publications Inc.. ; , s. 161-164
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Konferensbidrag (refereegranskat)abstract
- Carrier lifetime has been studied as a function of C/Si ratio and growth rate during epitaxial growth of n-type 4H-SiC using horizontal hot-wall CVD. Effort has been put on keeping all growth parameters constant with the exception of the parameter that is intended to vary. The carrier lifetime is found to decrease with increasing growth rate and the highest carrier lifetime is found for a C/Si ratio of 1. The surface roughness was correlated with epitaxial growth conditions with AFM analysis.
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| 8. |
- Lilja, Louise, et al.
(författare)
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The influence of growth conditions on carrier lifetime in 4H-SiC epilayers
- 2013
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Ingår i: Journal of Crystal Growth. - : Elsevier. - 0022-0248 .- 1873-5002. ; 381, s. 43-50
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Tidskriftsartikel (refereegranskat)abstract
- 4H-SiC homoepitaxial layers have been grown in a horizontal hot-wall CVD (chemical vapor deposition) reactor and the measured carrier lifetimes have been correlated to the CVD growth conditions. Two different generations of reactors were compared, resulting in measured carrier lifetimes in two different orders of magnitude, from a few hundreds of ns to a few ms. The variations in measured carrier lifetime were correlated to deep level concentrations of the Z(1/2) center and the D-1 center, seen by photoluminescence. Decreasing the growth temperature clearly prolonged the carrier life time and showed lower Z(1/2) concentrations, where as lowering the growth rate only showed a small improvement of the carrier lifetime and no obvious tendencyin Z(1/2) defect concentrations, indicating that Z(1/2) is not the only defect limiting the carrier lifetime. Increasing the C/Si ratio resulted in decreasing Z(1/2) concentrations, indicating the carbon vacancy nature of the defect. However, carrier lifetime measurements showed maximum values for a C/Si ratio of 1 but otherwise an increasing tendency for increasing C/Si ratios. The reactor giving higher carrier lifetimes, correspondingly also showed lower Z(1/2) concentrations indicating the lifetime limiting property of Z(1/2). Furthermore, the D-1 defect intensity increased with growth temperature and decreased with increasing C/Si ratio, similar to the Z(1/2) concentration.
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| 9. |
- Ul-Hassan, Jawad, et al.
(författare)
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Fast growth rate epitaxy on 4((degrees)under-bar) off-cut 4-inch diameter 4H-SiC wafers
- 2014
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Ingår i: SILICON CARBIDE AND RELATED MATERIALS 2013, PTS 1 AND 2. - : Trans Tech Publications. ; , s. 179-182
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Konferensbidrag (refereegranskat)abstract
- We report the development of over 100 mu m/h growth rate process on 4-inch diameter wafers using chlorinated growth. The optimized growth process has shown extremely smooth epilayers completely free of surface step-bunching with very low surface defect density, high uniformity in thickness and doping and high run to run reproducibility in growth rate, controlled doping and defect density.
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| 10. |
- ul Hassan, Jawad, et al.
(författare)
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On-axis homoepitaxial growth of 4H-SiC PiN structure for high power applications
- 2013
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Ingår i: Silicon Carbide and Related Materials 2012. - : Trans Tech Publications Inc.. - 9783037856246 ; 740-742, s. 173-176, s. 173-176
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Konferensbidrag (refereegranskat)abstract
- We demonstrate on-axis homoepitaxial growth of 4H-SiC(0001) PiN structure on 3-inch wafers with 100% 4H polytype in the epilayer excluding the edges. The layers were grown with a thickness of 105 μm and controlled n-type doping of 4 x 1014 cm-3.The epilayers were completely free of basal plane dislocations, in-grown stacking faults and other epitaxial defects, as required for 10 kV high power bipolar devices. Some part of the wafer had a lifetime enhancement procedure to increase lifetime to above 2 μs using carbon implantation. An additional step of epilayer polishing was adapted to reduce surface roughness and implantation damage.
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