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Growth of GaAs-based 1.3 μm InAs/InGaAs Quantum Dots and Lasers by Molecular Beam Epitaxy
No full text在本篇論文中，我們分別以氣態源分子束磊晶法和固態源分子束磊晶法研究在砷化鎵基板上成長長波長砷化銦/砷化銦鎵量子點及量子點雷射。
首先，我們以氣態源分子束磊晶法在(100)指向的砷化鎵基板上，有系統地研究成長放光波長為1.3 μm的量子點。我們發現以V/III比為2成長的砷化銦量子點，擁有最好的光學與表面結構特性。在砷化銦量子點上成長砷化銦鎵帽層，可使量子點放光紅移，同時放光強度會增強且半高寬會變窄。另外，砷化銦量子點的成長條件會嚴重影響砷化銦/砷化銦鎵量子點的品質。我們藉由不同的成長方法成長砷化銦鎵帽層，可在對放光強度影響不大的情況下，將砷化銦/砷化銦鎵量子點密度控制在2.3 × 1010到 1.7 × 1011 cm-2的範圍，且成功地成長出發光波長為1.32 μm、密度高達7.6 × 1010 cm-2的量子點。此外，我們結合在基板溫度530oC成長之砷化銦和以次原子層沈積法成長砷化銦鎵帽層的方法，成長出放光波長為1292 nm的高品質量子點，其光激螢光的半高寬為26 meV，量子點密度為4.5 × 1010 cm-2。
其次，我們以氣態源分子束磊晶法成長不含鋁之多層砷化銦/砷化銦鎵量子點雷射結構，並探討不同長晶方法對於量子點雷射特性的影響。以次原子層遷移強化法成長砷化銦鎵帽層，因單層量子點密度僅為2.3 × 1010 cm-2，即使使用4層的砷化銦/砷化銦鎵量子點雷射結構，雷射亦無法在基態達到起振。以傳統分子束磊晶法成長砷化銦鎵帽層，由於單層量子點密度高達1.7 × 1011 cm-2，故2層的砷化銦/砷化銦鎵量子點雷射在共振腔長度為1.5 mm時仍可達到基態起振；但以傳統分子束磊晶法成長高成分的砷化銦鎵帽層可能會有缺陷伴隨產生，而使起振電流密度高達5.3 KA/cm2。而使用次原子層沈積法成長砷化銦鎵帽層，則可同時兼顧高量子點密度與量子點的品質，使得量子點雷射能夠達到基態起振。3層的SMD量子點雷射在共振腔長度為3.96 mm時，其雷射起振放光波長為1305 nm，起振電流密度為360 A/cm2。最後，我們以結合高溫成長的砷化銦和次原子層沈積法成長的砷化銦鎵，獲得高均勻度的量子點，並製作出起振放光波長為1296 nm，起振電流密度為111 A/cm2的量子點雷射，據我們所知，這是目前成長在砷化鎵基板上不含鋁的1.3 μm雷射最低的起振電流密度值。
最後，我們以在氣態源分子束磊晶機研究得到之量子點磊晶方法，成功地應用在固態源分子束磊晶機上，並得到特性相當好的量子點雷射。首先，我們研究砷化銦鎵厚度對於砷化銦/砷化銦鎵量子點的影響。並發現覆蓋6.0 ML砷化銦鎵的砷化銦/砷化銦鎵量子點因無額外的缺陷產生，使得其量子點發光效率最好。以此長晶條件成長的3層砷化銦/砷化銦鎵量子點雷射，在共振腔長度為2.54 mm時，其起振電流密度為124 A/cm2，雷射起振放光波長為1212 nm。此量子點雷射之內部量子效率、外部量子效率內部損失、基態飽和增益和特徵溫度分別為74 %、59 %、2.5 cm-1、23.0 cm-1和59 K。In this disseration, high quality 1300 nm InAs/InGaAs quantum dots (QDs) and QD lasers grown by gas-source molecular-beam epitaxy (GSMBE) and solid-source molecular-beam epitaxy (SSMBE) were studied.
The growth condition for QDs with emission wavelength at 1.3 μm was systematically investigated by GSMBE on (100) GaAs substrates. InAs QDs grown at V/III ratio ~ 2 show the best structural and optical properties. After depositing InGaAs capping layer on top of the InAs QDs, the resultant InAs/InGaAs QDs have longer emission wavelength, stronger photoluminescence (PL) intensity, and narrower PL linewidth. It is also found that the growth condition of the InAs QDs could affect the quality of the InAs/InGaAs QDs significantly. With different deposition methods for the InGaAs capping layer, namely sub-monolayer migration-enhanced epitaxy (SMEE), sub-monolayer deposition (SMD) and traditional MBE deposition, the dot density of InAs/InGaAs QDs ranging from 2.3第一章 簡介 1
1.1 分子束磊晶技術簡介 1
1.2 量子點雷射的優點 2
1.3 論文概要 4
第二章 以氣態源分子束磊晶法成長放光波長在1.3 μm之InAs/InGaAs量子點 8
2.1 簡介 8
2.2 V/III通量比對於InAs量子點的影響 10
2.2.1 實驗方法 10
2.2.2 結果與討論 12
2.3 InGaAs厚度對於InAs/InGaAs量子點的影響 14
2.3.1 實驗方法 14
2.3.2 結果與討論 15
2.4 InGaAs成長方法對於InAs/InGaAs量子點的影響 19
2.4.1 實驗方法 19
2.4.2 結果與討論 19
2.5 成長溫度對於InAs和InAs/InGaAs量子點的影響 22
2.5.1 實驗方法 22
2.5.2 結果與討論 23
2.6 本章概要結論 28
第三章 以氣態源分子束磊晶法成長放光波長在1.
Photoreflectance Study on the Interface of InGaP/GaAs Heterostructures Grown by Gas Source Molecular Beam Epitaxy
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Ultrasensitive Electrical DNA Identification with Bio-Bar-Code DNA and Nanoparticles in Nanogap Device
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Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Apoyo sociofamiliar y funcionalidad del adulto mayor, una revisión sistemática
Full text linkAntecedentes: Un pilar fundamental en la salud del adulto mayor es su
funcionalidad, donde el apoyo sociofamiliar juega un papel importante.
Objetivo: Determinar la asociación entre el apoyo sociofamiliar y la
funcionalidad del adulto mayor.
Metodología: Revisión sistemática de 18 estudios basados en dominios
específicos y criterios STROBE, del 2015 al 2020 en los idiomas inglés y
español, cuyas bases de datos fueron Pubmed, Scopus y Science Direct, se
usó términos MesH y operadores booleanos. La información destacada se
sintetizó en tablas personalizadas.
Resultados: Prevalencia de apoyo sociofamiliar entre 17,8% y 97,14%,
identificándose 4 tipos: apoyo social, participación social, apoyo familiar y apoyo
sociofamiliar. La funcionalidad se describió como actividades de la vida diaria
básicas (ABVD) e instrumentales (AIVD), encontrándose prevalencias altas de
ABVD y AIVD 86,6% y 86,3% respectivamente, y prevalencias bajas de 4,27%
y 10,3%. El apoyo sociofamiliar y la funcionalidad tuvieron asociación
significativa en la mayoría estudios, identificándose en 4 estudios que la falta
de apoyo sociofamiliar es un factor de riesgo para deterioro funcional con un
OR mayor a uno y un IC del 95%.
Conclusiones: Existe relación significativa entre el apoyo sociofamiliar y la
funcionalidad del adulto mayor, su ausencia es un factor de riesgo para
deterioro funcional.
Limitaciones: La heterogeneidad metodológica de los estudios encontrados, la
falta de datos estadísticos y de accesibilidad a información por rubros
económicosBackground: A fundamental pillar in the health of the elderly is its functionality,
where socio-family support plays an important role.
Objective: To determine the association between socio-family support and the
functionality of the elderly.
Methodology: Systematic review of 18 studies based on specific domains and
STROBE criteria, from 2015 to 2020 in English and Spanish, whose databases
were Pubmed, Scopus and Science Direct, using MesH terms and Boolean
operators. The highlighted information was synthesized in personalized tables.
Results: Prevalence of socio-family support between 17.8% and 97.14%,
identifying 4 types: social support, social participation, family support and socio family support. Functionality was described as basic activities of daily living
(BADL) and instrumental activities (IADL), finding high prevalences of BADL
and IADL 86.6% and 86.3% respectively, and low prevalences of 4.27% and
10.3 %. Socio-family support and functionality had a significant association in
most studies, identifying in 4 studies that the lack of socio-family support is a
risk factor for functional deterioration with an OR greater than one and a 95%
CI.
Conclusions: There is a significant relationship between socio-family support
and the functionality of the elderly, its absence is a risk factor for functional
deterioration.
Limitations: The methodological heterogeneity of the studies found, the lack of
statistical data and accessibility to information by economic items.Especialista en Medicina Familiar y ComunitariaCuenc
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