Physics of Wurtzite Nitrides and Oxides

Gil, Bernard

doi:10.1007/978-3-319-06805-3

Cited by 23 publications

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“…O AlN foi descoberto em 1862, mas a primeira síntese ocorreu apenas em 1876 [20]. Esta cerâmica não exibe ponto de fusão, pois se dissocia em alumínio (Al) e nitrogênio (N) acima de 2230 ºC [20].…”

Section: Síntese E Hidrólise Do Nitreto De Alumíniounclassified

“…Esta cerâmica não exibe ponto de fusão, pois se dissocia em alumínio (Al) e nitrogênio (N) acima de 2230 ºC [20]. Embora seja considerado covalente [13], o AlN é constituído por ligações tanto covalente (60%) como iônica (40%) [21], tendo estrutura cristalina hexagonal compacta 2H similar à da wurtzita [13,20]. A cerâmica de AlN é sintetizada a partir de matérias-primas industrializadas, como pós de alumínio (Al) ou de Al 2 O 3 .…”

Section: Síntese E Hidrólise Do Nitreto De Alumíniounclassified

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Processamento, propriedades e aplicações das cerâmicas de nitreto de alumínio

Molisani

2017

Cerâmica

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INTRODUÇÃOA tecnologia planar em silício possibilitou a fabricação de dispositivos eletrônicos miniaturizados (circuitos integrados ou chips). Este processo avançou até atingir dimensões que resultaram em problemas tanto de flexibilização funcional como de custos efetivos, que inviabilizaram a produção de chips com alta complexidade. Os referidos problemas foram solucionados com o advento da tecnologia de circuitos passivos, que é responsável pela fabricação de substratos e componentes para encapsulamento (packaging), os quais são acoplados ao chip de silício para fornecer interconexão,

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Section: Síntese E Hidrólise Do Nitreto De Alumíniounclassified

Processamento, propriedades e aplicações das cerâmicas de nitreto de alumínio

Molisani

2017

Cerâmica

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“…Over the past decade, III-nitride-based semiconductors have reached a high level of dissemination second only to silicon based on a wide range of applications covering both electronics and optoelectronics [38]. Many aspects of our daily life are already impacted by III-nitride-based lightemitting diodes (LEDs) and laser diodes [39,40], while high-power electronics is also on the rise [41,42].…”

Section: Introductionmentioning

confidence: 99%

Probing Alloy Formation Using Different Excitonic Species: The Particular Case of InGaN

2019

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Since the early 1960s, alloys are commonly grouped into two classes that feature either bound states in the band gap (I) or additional, nondiscrete band states (II). Consequently, one can observe either excitons bound to isoelectronic impurities or the typical band edge emission of a semiconductor that shifts and broadens with rising isoelectronic doping concentration. Microscopic parameters for class I alloys can directly be extracted from photoluminescence (PL) spectra, whereas any conclusions drawn for class II alloys usually remain limited to macroscopic assertions. Nonetheless, we present a spectroscopic study on exciton localization in a mixed-crystal alloy (class II) that allows us to access microscopic alloy parameters. In order to illustrate our approach, we study bulk In x Ga 1−x N epilayers at the onset of alloying (0 ≤ x ≤ 2.4%) in order to understand their robustness to point and structural defects. Through an indepth PL analysis it is demonstrated how different excitonic complexes (free, bound, and complex bound excitons) can serve as a probe to monitor the dilute limit of class II alloys. From an x-dependent linewidth analysis we extract the length scales at which excitons become increasingly localized, i.e., their conversion from a free to a bound particle upon alloy formation. Already at x ¼ 2.4% the exciton diffusion length is reduced to 5.7 AE 1.3 nm at a temperature of 12 K; hence, detrimental exciton transfer mechanisms toward nonradiative defects are suppressed. In addition, the associated low-temperature PL data suggest that a single indium atom cannot permanently capture an exciton. The low density of silicon impurities in our samples even allows studying their local indium-enriched environment at the scale of the exciton Bohr radius based on impurity bound excitons. The associated temperature-dependent PL data reveal an alloying dependence for the exciton-phonon coupling. Thus, the formation of the random alloy can not only be monitored by the emission of various excitonic complexes, but also more indirectly via the associated coupling(s) to the phonon bath. Micro-PL spectra even give access to a probing of silicon bound excitons embedded in a particular environment of indium atoms thanks to the emergence of a series of individual and energetically sharp emission lines (full width at half maximum ≈300 μeV). Consequently, the present study allows us to extract microscopic properties formerly mostly only accessible for class I alloys.

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“…Over the past decade, III-nitride-based semiconductors have reached a high level of dissemination only second to silicon based on a wide range of applications covering both, electronics and optoelectronics [33]. Many aspects of our daily life are already impacted by III-nitride-based light-emitting and laser diodes (LEDs and LDs) [34,35], while high-power electronics is also on the rise [36,37].…”

Section: Introductionmentioning

confidence: 99%

Probing alloy formation using different excitonic species: The particular case of InGaN

Callsen

Butté

2019

2019 Compound Semiconductor Week (CSW)

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Since the early 1960s, alloys are commonly grouped into two classes, featuring bound states in the bandgap (I) or additional, non-discrete, band states (II). As a consequence, one can observe either a rich and informative zoo of excitons bound to isoelectronic impurities (I), or the typical bandedge emission of a semiconductor that shifts and broadens with rising isoelectronic doping concentration (II). Microscopic material parameters for class I alloys can directly be extracted from photoluminescence (PL) spectra, whereas any conclusions drawn for class II alloys usually remain indirect and limited to macroscopic assertions. Nonetheless, here, we present a comprehensive spectroscopic study on exciton localization in a so-called mixed crystal alloy (class II) that allows us to access microscopic alloy parameters. In order to exemplify our experimental approach we study bulk InxGa1−xN epilayers at the onset of alloy formation (0 ≤ x ≤ 2.4%) in order to understand the material's particular robustness to point and structural defects. Based on an in-depth PL analysis it is demonstrated how different excitonic complexes (free, bound, and complex bound excitons) can serve as a probe to monitor the dilute limit of class II alloys. From an x-dependent linewidth analysis we extract the length scales at which excitons become increasingly localized, meaning that they convert from a free to a bound particle upon alloy formation. Already at x = 2.4% the average exciton diffusion length is reduced to 5.7±1.3 nm at a temperature of 12 K, thus, detrimental exciton transfer mechanisms towards non-radiative defects are suppressed. In addition, the associated low temperature luminescence data suggests that a single indium atom does not suffice in order to permanently capture an exciton. The low density of silicon impurities in our samples even allows studying their local, indium-enriched environment at the length scale of the exciton Bohr radius based on impurity bound excitons. The associated temperature-dependent PL data reveals an alloying dependence for the exciton-phonon coupling. Thus, the formation of the random alloy can not only directly be monitored by the emission of various excitonic complexes, but also more indirectly via the associated coupling(s) to the phonon bath. Micro-PL spectra even give access to a forthright probing of silicon bound excitons embedded in a particular environment of indium atoms, thanks to the emergence of a hierarchy of individual, energetically sharp emission lines (full width at half maximum ≈ 300 µeV). Consequently, the present spectroscopic study allows us to extract first microscopic alloy properties formerly only accessible for class I alloys. * gordon.callsen@epfl.ch tronic centers (II) evokes the formation of mixed crystal alloys like, e.g., SiGe [14], GaAsP [15], InGaAs [16], AlGaAs [17], InGaN [18], AlGaN [19], CdSSe [20, 21], ZnSeTe [21], and MgZnO [22]. In these cases, no new electronic levels are formed in the bandgap, but rather in the bands themselves, a process often described a...

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Physics of Wurtzite Nitrides and Oxides

Cited by 23 publications

References 0 publications

Processamento, propriedades e aplicações das cerâmicas de nitreto de alumínio

Processamento, propriedades e aplicações das cerâmicas de nitreto de alumínio

Probing Alloy Formation Using Different Excitonic Species: The Particular Case of InGaN

Probing alloy formation using different excitonic species: The particular case of InGaN

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