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Record Nr. |
UNINA9911046723803321 |
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Autore |
della Casa Pietro |
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Titolo |
Two-step MOVPE, in-situ etching and buried implantation |
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Pubbl/distr/stampa |
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Göttingen : , : Cuvillier Verlag, , 2021 |
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©2021 |
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ISBN |
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Edizione |
[1st ed.] |
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Descrizione fisica |
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1 online resource (251 pages) |
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Collana |
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Innovationen mit Mikrowellen und Licht. Forschungsberichte aus dem Ferdinand-Braun-Institut, Leibniz-Institut für Höchstfrequenztechnik ; ; v.63 |
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Disciplina |
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Soggetti |
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Lingua di pubblicazione |
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Formato |
Materiale a stampa |
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Livello bibliografico |
Monografia |
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Nota di contenuto |
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Intro -- 1 Introduction -- 2 Zincblende III-V semiconductors -- 2.2 Zincblende crystal structure -- 2.3 Point defects in III-V semiconductors -- 2.4 III-V semiconductors and optoelectronics -- 3 MOVPE growth of III-V compounds -- 3.1 Introductory remarks on the MOVPE technique -- 3.2 Planetary reactors AIX2400G3 and AIX2800G4 -- 3.3 Precursors selected for the experimental work -- 3.4 Dopants and impurities incorporation -- 4 In-situ etching with CBr4 -- 4.1 Motivation for in-situ etching -- 4.2 Pre-existing research on in-situ etching -- 4.3 Investigation of CBr4 etching of GaAs -- 4.4 Investigation of CBr4 etching of GaAs assisted with TMGa and TMAl -- 4.5 CBr4 etching of AlGaAs and GaInP -- 5 SG-DBR tunable lasers -- 5.1 Chapter introduction -- 5.2 SG-DBR lasers -- 5.3 Thermally tuned SG-DBR lasers -- 5.4 Investigation of electronic tuning -- 6 Buried-mesa broad-area lasers -- 6.1 Chapter introduction -- 6.2 High-power lasers -- 6.3 Structure and process -- 6.4 Results and discussion -- 6.5 Chapter summary and conclusions -- 7 Lasers with buried implantation -- 7.1 Chapter introduction -- 7.2 Ion implantation -- 7.3 Device description and fabrication procedure -- 7.4 Material characterization -- 7.5 Characterization of as-cleaved devices -- 7.6 Characterization of coated and mounted devices -- 7.7 Step-stress |
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tests -- 7.8 Chapter summary and conclusions -- 8 Summary and outlook -- A1 Zincblende III-V semiconductors and related properties -- A1.1 Appendix content -- A1.2 Composition, bonding and related properties -- A1.3 Crystal structure -- A1.4 Ternary and higher order compounds -- A1.5 Epitaxial multilayers: mismatch, strain, relaxation -- A1.6 Defects -- A1.7 Electronic structure and related properties -- A1.8 Carrier transport -- A1.9 Interband transitions -- A1.10 Optical properties in the transparency region. |
A2 Some general aspects of III-V MOVPE -- A2.1 Different III-V epitaxy techniques -- A2.2 General considerations about MOVPE reactors -- A2.3 Precursors for the growth of arsenides and phosphides -- A2.4 Surface processes -- A2.5 Stoichiometry, composition and impurity control in MOVPE -- A3 Justification of the equations used in modeling the CBr4+TMAl etch -- A4 Model for the calculation of αip in the implanted sections -- Glossary -- References. |
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Sommario/riassunto |
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This work is about two-step epitaxial growth using metalorganic vapor-phase epitaxy (MOVPE) for the realization of edge-emitting near-infrared laser diodes. The fabricated gallium arsenide-based devices fall into two categories: high-power lasers (watt range, multimodal) and tunable lasers (milliwatt range, monomodal). Common to both cases is that surface contamination - particularly that due to oxygen - needs to be removed before regrowth. Thus, in-situ etching with carbon tetrabromide (CBr4) is first studied. The experimental results include kinetic data, the effects of different etching conditions as well as substrate characteristics, and the effectiveness in reducing surface contamination.These investigations pave the way to devices based on 2-step epitaxy combined with in-situ etching. Correspondingly, thermally-tuned SG-DBR lasers operating around 975 nm have been successfully realized, obtaining a tuning range of 21 nm. In addition, the possibility of using electronic tuning in similar devices has been explored.High-power broad-area lasers have also been realized, using two-step epitaxy combined with ex-situ and in-situ etching, to create a buried, shallow "mesa" containing the active zone. This approach allows introducing lateral electrical and optical confinement, and - simultaneously - non-absorbing mirrors at the laser facets.Additionally, a different strategy to create a buried current aperture is presented, which is based on ion implantation followed by epitaxial regrowth. This enables to improve device performance and simultaneously introduce non-absorbing mirrors at the facets with correspondingly increased reliability. |
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2. |
Record Nr. |
UNINA9910961088603321 |
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Autore |
Weiß Volker |
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Titolo |
Deutschlands Neue Rechte : Angriff der Eliten - Von Spengler bis Sarrazin / Volker Weiß |
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Pubbl/distr/stampa |
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Paderborn, : Brill | Schöningh, 2012 |
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ISBN |
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Edizione |
[1st ed.] |
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Descrizione fisica |
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Disciplina |
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Soggetti |
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Faschismus |
Nationalsozialismus |
Neue Rechte |
Politik |
Staat |
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Lingua di pubblicazione |
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Formato |
Materiale a stampa |
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Livello bibliografico |
Monografia |
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Nota di contenuto |
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Preliminary Material -- Apokalypse 2010 – Schafft Deutschland sich ab? -- Deutsche Untergänge -- Der Weg zur selbstbewussten Nation -- Die anthropotechnische Wende -- Die Angst vor den Massen -- Demographie und Krise -- Partisanen im Diskurs -- Falsche Propheten -- Nachweise. |
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Sommario/riassunto |
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Die Forderung nach »Elite« hat Konjunktur. Dabei wohnt der Debatte die Tendenz inne, vom Bestehen gesellschaftlicher Funktionseliten auf die Existenz einer generell höher begabten Menschengruppe zu schließen. Die Befähigung zur »Elite« wird schließlich auf die biologische Disposition einer privilegierten Gruppe zurückgeführt: ihre »Rasse«, vererbte Intelligenz oder genetische Veranlagung.Volker Weiß analysiert, wie sich das Bedürfnis nach Abgrenzung einer Elite in Deutschlands jüngerer Vergangenheit äußerte: von Ortega y Gasset und Friedrich Sieburg über Botho Strauß bis hin zu Peter Sloterdijk und Thilo Sarrazin. Er weist nach, dass dieses Bedürfnis nach »Elite« in direkter Tradition der republikfeindlichen Theoretiker der Weimarer Zeit steht und heute von einer »neuen« Rechten befeuert wird, der an einer konservativen Revolution gelegen ist. Ihr Ziel ist die Revision gesellschaftlicher Liberalisierungen seit dem Ende der sechziger Jahre. |
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Neu ist, dass sich diese Strömung nicht nur mit dem Gestus der Opfer und Tabubrecher präsentiert, sondern dass sie mit dieser Strategie Erfolg hat. |
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