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- Dochev, Dimitar Milkov, 1981, et al.
(författare)
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The influence of aging and annealing on the properties of Nb/Al-AlOx/Nb tunnel junctions
- 2010
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Ingår i: Journal of Physics: Conference Series. - : IOP Publishing. - 1742-6588 .- 1742-6596. ; 234:4
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Konferensbidrag (refereegranskat)abstract
- This paper presents results of our studies on aging and annealing properties of Nb/Al-AlOx/Nb junctions. We performed a long room temperature aging with subsequent annealing at different temperatures up to 250°C. A distinct change of the junctions' normal-state resistance has been observed. Aging at room temperature results in a slight decrease of the normal-state resistance combined with improved junction quality, characterised by a better subgap-to-normal resistance ratio. Annealing at moderate temperatures in air increases the normal-state resistance and leads to improvement of the junction quality followed by degradation at higher annealing temperatures. The increase in the junction quality after long-term aging at room temperature is attributed to relaxation of the internal junction structure and interfaces, thus, resulting in a lower density of interface traps. The deterioration at higher annealing temperatures could be a consequence of diffusion processes at the Al/Nb interface. We observe a sufficiently clear difference between the behaviour of preliminary aged and newly fabricated junctions after annealing: for the aged high-quality junction, the degradation was negligible up to temperatures of 200°C, while non-aged junctions show a much faster and abrupt degradation at lower annealing temperatures.
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| 2. |
- Song, Yuxin, 1981, et al.
(författare)
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Enhancement of optical quality in metamorphic quantum wells using dilute nitride buffers
- 2010
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Ingår i: Applied Physics Letters. - : AIP Publishing. - 0003-6951 .- 1077-3118. ; 97:9, s. 091903-
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Tidskriftsartikel (refereegranskat)abstract
- Strong enhancement of optical quality in quantum wells by incorporating nitrogen in metamorphic InGaAs buffers grown on GaAs substrates is demonstrated. This has resulted in 3.7 or 5.4 times enhancement of photoluminescence intensity from the metamorphic quantum wells when using dilute nitride superlattice alone or adding nitrogen in a strain compensated GaAs/In0.3Al0.7As superlattice, respectively. This study shows great potentials by incorporating N in metamorphic buffers to further improve the quality of metamorphic optoelectronic devices.
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