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- Forsberg, Urban, et al.
(författare)
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Improved hot-wall MOCVD growth of highly uniform AlGaN/GaN/HEMT structures
- 2009
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Ingår i: Journal of Crystal Growth. - : Elsevier BV. - 0022-0248 .- 1873-5002. ; 311:10, s. 3007-3010
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Tidskriftsartikel (refereegranskat)abstract
- The inherent advantages of the hot-wall metal organic chemical vapor deposition (MOCVD) reactor (low temperature gradients, less bowing of the wafer during growth, efficient precursor cracking) compared to a cold-wall reactor make it easier to obtain uniform growth. However, arcing may occur in the growth chamber during growth, which deteriorates the properties of the grown material. By inserting insulating pyrolytic BN (PBN) stripes in the growth chamber we have completely eliminated this problem. Using this novel approach we have grown highly uniform, advanced high electron mobility transistor (HEMT) structures on 4 semi-insulating (SI) SiC substrates with gas-foil rotation of the substrate. The nonuniformities of sheet resistance and epilayer thickness are typically less than 3% over the wafer. The room temperature hall mobility of the 2DEG is well above 2000 cm(2)/V s and the sheet resistance about 270 Omega/sqr.
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- Henry, Anne, et al.
(författare)
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AlGaN Multiple Quantum Wells and AlN Grown in a Hot-wall MOCVD for Deep UV Applications
- 2009
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Ingår i: ECS Transactions, Vol. 25, Iss. 8. - : ECS. - 9781566777452 ; , s. 837-844
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Konferensbidrag (refereegranskat)abstract
- AlxGa1-xN multiple quantum wells (MQW) were grown on AlN epilayer grown on 4H-SiC substrate. The growth was performed without interruption in a horizontal hot-wall MOCVD reactor using a mixture of hydrogen and nitrogen as carrier gases. The precursors were ammonia, trimethylaluminum and trimethylgallium. Results obtained from X-ray diffraction and infra-red reflectance were used to obtain the composition of the films when growing simple AlxGa1 xN layer. Visible reflectance was used to evaluate the thickness of the films. Finally the MQW parameters as thicknesses and composition variation were obtained by scanning transmission electron microscopy and demonstrated an agreement with the growth parameters used
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- Kakanakova-Georgieva, Anelia, 1970-, et al.
(författare)
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AlGaInN metal-organic-chemical-vapor-deposition gas-phase chemistry in hydrogen and nitrogen diluents : First-principles calculations
- 2006
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Ingår i: Chemical Physics Letters. - : Elsevier BV. - 0009-2614 .- 1873-4448. ; 431:4-6, s. 346-351
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Tidskriftsartikel (refereegranskat)abstract
- Direct impact of H2 and N2 diluents on the metal-organic-chemical-vapor-deposition gas-phase chemistry in M(CH3)3/NH3 (M = Al, Ga, In) systems is identified in the framework of Density Functional Theory in terms of cohesive energy differences. While both diluents destabilize model reaction species, i.e. adducts, transition states and chain complexes, the effect is particularly strong with respect to N2 in the Al(CH3)3/NH3 system, and can be a factor to restrain the expansion of chain complexes that deplete the gas-phase from precursors. Theoretical results are supported by experimental evidences of higher growth rate and superior optical properties of AlN grown in N2 vs. H2 diluent. © 2006 Elsevier B.V. All rights reserved.
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- Kakanakova-Georgieva, Anelia, 1970-, et al.
(författare)
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Hot-Wall MOCVD for Highly Efficient and Uniform Growth of AIN
- 2009
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Ingår i: Crystal Growth & Design. - : American Chemical Society (ACS). - 1528-7483 .- 1528-7505. ; 9:2, s. 880-884
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Tidskriftsartikel (refereegranskat)abstract
- We demonstrated successful growth of AIN at a temperature of 1200 degrees C in a set of hot-wall MOCVD systems with the possibility of straightforward scaling up the process on larger wafer areas to meet the demand of device technologies. We outlined several aspects of the carefully optimized design and process parameters with relevance to achievement of a high overall growth rate (1 and up to 2 mu m/h), efficiency, and uniformity, which to a great extent depends on how consumption of growth-limiting species by gas-phase adduct formation can actively be prevented. Mixing of the precursors upstream from the deposition area facilitates uniform epitaxial growth, while the greater uniformity of substrate temperature inherent to the hot-wall reactor and rotation of the wafer are of fundamental importance for layer-growth uniformity. The AIN layer thickness can be controlled with an accuracy of +/- 1.3% on 2 in. wafers. The low-temperature cathodoluminescence spectrum of the AIN epitaxial material is strongly dominated by the intense near band-gap deep UV emission at about 208 nm.
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