| 1. |
- Tiira, Jonna, et al.
(författare)
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Intracavity double diode structures with GaInP barrier layers for thermophotonic cooling
- 2017
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Ingår i: Optical and Electronic Cooling of Solids II. - : SPIE. - 9781510606838 ; 10121
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Konferensbidrag (refereegranskat)abstract
- Optical cooling of semiconductors has recently been demonstrated both for optically pumped CdS nanobelts and for electrically injected GaInAsSb LEDs at very low powers. To enable cooling at larger power and to understand and overcome the main obstacles in optical cooling of conventional semiconductor structures, we study thermophotonic (TPX) heat transport in cavity coupled light emitters. Our structures consist of a double heterojunction (DHJ) LED with a GaAs active layer and a corresponding DHJ or a p-n-homojunction photodiode, enclosed within a single semiconductor cavity to eliminate the light extraction challenges. Our presently studied double diode structures (DDS) use GaInP barriers around the GaAs active layer instead of the AlGaAs barriers used in our previous structures. We characterize our updated double diode structures by four point probe IV-measurements and measure how the material modifications affect the recombination parameters and coupling quantum efficiencies in the structures. The coupling quantum efficiency of the new devices with InGaP barrier layers is found to be approximately 10 % larger than for the structures with AlGaAs barriers at the point of maximum efficiency.
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| 2. |
- Torregrosa Hetland, Sara, et al.
(författare)
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Impact of innovation policy on firm innovation : A comparison of Finland and Sweden, 1970-2013
- 2017
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Annan publikation (övrigt vetenskapligt/konstnärligt)abstract
- To what extent have public policies contributed to the innovation performance of Finland and Sweden in the period 1970-2013? This paper aims to assess the share of innovations stimulated by the public sector, specifically because of receiving public funding or being the result of research collaboration with public institutions. We combine survey and LBIO results on these variables, to overcome reporting biases found in the two methods.The main data comes from the new UDIT dataset, which gathers the most significant innovations of both countries for the period, in total about 4,100 Swedish and 2,600 Finnish innovations. It has been constructed following the LBIO method (Literature Based Innovation Output), which obtains information on relevant commercialized innovations from general technology journals as well as industry specific trade journals.Our results indicate that Finland had a substantially larger public involvement in these innovations than Sweden. This is specially true in the years between 1990 and 2000, when we see a drop in the relative role of the Swedish public sector in innovation output, while the Finnish trends are constant or slightly increasing over the period. However, in both countries public policies lie behind a significant share of the innovations (30-50% in Finland, 15-35% in Sweden), and in the Swedish case we can further assess that the publicly stimulated innovations were more often found among the most significant new products (written about in several articles).
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| 3. |
- Torregrosa-Hetland, Sara, et al.
(författare)
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The prevalence of publicly stimulated innovations – A comparison of Finland and Sweden, 1970–2013
- 2019
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Ingår i: Research Policy. - : Elsevier BV. - 0048-7333.
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Tidskriftsartikel (refereegranskat)abstract
- While the role played by the state in stimulating innovation in the private sector has been a prevalent interest in innovation research, studies analysing the impacts of public interventions have usually focused on individual policies, programs or projects. Public stimulation is hence often studied from a relatively restricted and temporarily confined perspective, leaving a macro-level and longer-term perspective unrecognized. This article provides further evidence on the matter by examining how many innovations in Finland and Sweden have been publicly stimulated through funding or research collaboration, over a period of more than four decades (1970–2013). Our main source is a new innovation database constructed following the Literature Based Innovation Output (LBIO) method, which gathers the most significant innovations of both countries for the study period, totalling approximately 4100 Swedish and 2600 Finnish innovations. Our results indicate that the public sector has played a very prominent role in stimulating private innovation in both countries, and with an increasing trend. This is especially true for Finland, where 35–55% of the innovations of the period have been stimulated by public funding and 25–65% by collaboration with public research. In Sweden, the share of publicly stimulated innovations has been somewhat lower and erratic, but has increased over time.
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| 4. |
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