Molecular beam epitaxy growth of an In;Ga;As/GaAs quantum well（QW） structure（x equals to 0.17 or 0.3） on offcut（100） Ge substrate has been investigated.The samples were characterized by atomic force microscopy,p...Molecular beam epitaxy growth of an In;Ga;As/GaAs quantum well（QW） structure（x equals to 0.17 or 0.3） on offcut（100） Ge substrate has been investigated.The samples were characterized by atomic force microscopy,photoluminescence（PL）,and high resolution transmission electron microscopy.High temperature annealing of the Ge substrate is necessary to grow GaAs buffer layer without anti-phase domains.During the subsequent growth of the GaAs buffer layer and an In;Ga;As/GaAs QW structure,temperature plays a key role. The mechanism by which temperature influences the material quality is discussed.High quality In;Ga;As/GaAs QW structure samples on Ge substrate with high PL intensity,narrow PL linewidth and flat surface morphology have been achieved by optimizing growth temperatures.Our results show promising device applications forⅢ-Ⅴcompound semiconductor materials grown on Ge substrates.展开更多
Top-illuminated metamorphic InGaAs p-i-n photodetectors （PDs） with 50% cut-off wavelength of 1.75 μm at room temperature are fabricated on GaAs substrates. The PDs are grown by a solid-source molecular beam epitaxy...Top-illuminated metamorphic InGaAs p-i-n photodetectors （PDs） with 50% cut-off wavelength of 1.75 μm at room temperature are fabricated on GaAs substrates. The PDs are grown by a solid-source molecular beam epitaxy system. The large lattice mismatch strain is accommodated by growth of a linearly graded buffer layer to create a high quality virtual InP substrate indium content in the metamorphic buffer layer linearly changes from 2% to 60%. The dark current densities are typically 5 × 10^-6 A/cm^2 at 0 V bias and 2.24 × 10^-4 A/cm^2 at a reverse bias of 5 V. At a wavelength of 1.55 μm, the PDs have an optical responsivity of 0.48 A/W, a linear photoresponse up to 5 mW optical power at -4 V bias. The measured -3 dB bandwidth of a 32 μm diameter device is 7 GHz. This work proves that InGaAs buffer layers grown by solid source MBE are promising candidates for GaAs-based long wavelength devices.展开更多
Molecular beam epitaxy growth of a bilayer stacked InAs/GaAs quantum dot structure on a pure GaAs matrix has been systemically investigated.The influence of growth temperature and the InAs deposition of both layers on...Molecular beam epitaxy growth of a bilayer stacked InAs/GaAs quantum dot structure on a pure GaAs matrix has been systemically investigated.The influence of growth temperature and the InAs deposition of both layers on the optical properties and morphologies of the bilayer quantum dot（BQD） structures is discussed.By optimizing the growth parameters,InAs BQD emission at 1.436μm at room temperature with a narrower FWHM of 27 meV was demonstrated.The density of QDs in the second layer is around 9×10~9 to 1.4×10^（10） cm^（-2）. The BQD structure provides a useful way to extend the emission wavelength of GaAs-based material for quantum functional devices.展开更多
The solar spectrum covers a broad wavelength range, which requires that antireflection coating （ARC） is effective over a relatively wide wavelength range for more incident light coming into the cell. In this paper, ...The solar spectrum covers a broad wavelength range, which requires that antireflection coating （ARC） is effective over a relatively wide wavelength range for more incident light coming into the cell. In this paper, we present two methods to measure the composite reflection of SiO2/ZnS double-layer ARC in the wavelength ranges of 300-870 nm （duaI- junction） and 300-1850 nm （triple-junction）, under the solar spectrum AM0. In order to give sufficient consideration to the ARC coupled with the window layer and the dispersion effect of the refractive index of each layer, we use multidimensional matrix data for reliable simulation. A comparison between the results obtained from the weighted-average reflectance （WAR） method commonly used and that from the effective-average reflectance （EAR） method introduced here shows that the optimized ARC through minimizing the effective-average reflectance is convenient and available.展开更多
Tunable metamorphic InGaAs partially depleted absorber photodiodes with resonant cavity enhanced structure are fabricated on GaAs substrate.Dark-current densities of 7.2×10^(-7)A/cm^(2) at 0 V and 3.6×10^(-4...Tunable metamorphic InGaAs partially depleted absorber photodiodes with resonant cavity enhanced structure are fabricated on GaAs substrate.Dark-current densities of 7.2×10^(-7)A/cm^(2) at 0 V and 3.6×10^(-4)A/cm^(2) at-5 V,a high quantum efficiency of 74.4%at 1546nm,and a 3-dB bandwidth up to 12GHz are achieved.The full width at half maximum of the detector is about 16nm.Furthermore,through thermal tuning,the peak wavelength red shifts from 1527nm to 1544 nm,and a tuning range of 17nm is realized without fabricating extra tuning electrodes.展开更多
The GaAs based InGaAs metamorphic structures and their growth by molecular beam epitaxy (MBE) are investigated. The controlling of the source temperature is improved to realize the linearly graded InGaAs metamorphic s...The GaAs based InGaAs metamorphic structures and their growth by molecular beam epitaxy (MBE) are investigated. The controlling of the source temperature is improved to realize the linearly graded InGaAs metamorphic structure precisely. The threading dislocations are reduced. We also optimize the growth and annealing parameters of the InGaAs quantum well (QW). The 1.3-μm GaAs based metamorphic InGaAs QW is completed. A 1.3-μm GaAs based metamorphic laser is reported.展开更多
According to the theory of optical films,we simulate the reflectivity of antireflection coatings(ARCS)for solar cells of Gao.51no.5P/GaAs/Ge based on an optical transfer matrix.In order to provide sufficient considera...According to the theory of optical films,we simulate the reflectivity of antireflection coatings(ARCS)for solar cells of Gao.51no.5P/GaAs/Ge based on an optical transfer matrix.In order to provide sufficient consideration of the refractive index dispersion effect of multilayer ARCS,we use multi-dimensional matrix data for reliable simulation.After the reflection curves are obtained,the effective average reflectance Re is introduced to optimize the film system by minimizing Re.Optimization of single layer(A1_(2)0_(3)),double layer(MgF_(2)/ZnS)and triple layer(MgF_(2)/A1_(2)0_(3)/ZnS)ARCS is realized by using this method for space and terrestrial applications.Effects of these ARCS are compared after optimization.These theoretical parameters can be used to guide experiments.展开更多
Molecular beam epitaxy growth of GaAs on an offcut Ge （100） substrate has been systemically investigated. A high quality GaAs/Ge interface and CaAs film on Ge have been achieved. High temperature annealing before Ga...Molecular beam epitaxy growth of GaAs on an offcut Ge （100） substrate has been systemically investigated. A high quality GaAs/Ge interface and CaAs film on Ge have been achieved. High temperature annealing before GaAs deposition is found to be indispensable to avoid anti-phase domains. The quality of the GaAs film is found to strongly depend on the GaAs/Ge interface and the beginning of GaAs deposition. The reason why both high temperature annealing and GaAs growth temperature can affect epitaxial GaAs film quality is discussed. High quality InonTGao.s3As/GaAs strained quantum wells have also been achieved on a Ge substrate. Samples show flat surface morphology and narrow photoluminescence line width compared with the same structure sample grown on a GaAs substrate. These results indicate a large application potential for Ⅲ-Ⅴcompound semiconductor optoelectronic devices on Ge substrates.展开更多
基金Project supported by the National Natural Science Foundation of China(No60625405)the National Basic Research Program of China (Nos2007CB936304,2010CB327601)
文摘Molecular beam epitaxy growth of an In;Ga;As/GaAs quantum well（QW） structure（x equals to 0.17 or 0.3） on offcut（100） Ge substrate has been investigated.The samples were characterized by atomic force microscopy,photoluminescence（PL）,and high resolution transmission electron microscopy.High temperature annealing of the Ge substrate is necessary to grow GaAs buffer layer without anti-phase domains.During the subsequent growth of the GaAs buffer layer and an In;Ga;As/GaAs QW structure,temperature plays a key role. The mechanism by which temperature influences the material quality is discussed.High quality In;Ga;As/GaAs QW structure samples on Ge substrate with high PL intensity,narrow PL linewidth and flat surface morphology have been achieved by optimizing growth temperatures.Our results show promising device applications forⅢ-Ⅴcompound semiconductor materials grown on Ge substrates.
文摘Top-illuminated metamorphic InGaAs p-i-n photodetectors （PDs） with 50% cut-off wavelength of 1.75 μm at room temperature are fabricated on GaAs substrates. The PDs are grown by a solid-source molecular beam epitaxy system. The large lattice mismatch strain is accommodated by growth of a linearly graded buffer layer to create a high quality virtual InP substrate indium content in the metamorphic buffer layer linearly changes from 2% to 60%. The dark current densities are typically 5 × 10^-6 A/cm^2 at 0 V bias and 2.24 × 10^-4 A/cm^2 at a reverse bias of 5 V. At a wavelength of 1.55 μm, the PDs have an optical responsivity of 0.48 A/W, a linear photoresponse up to 5 mW optical power at -4 V bias. The measured -3 dB bandwidth of a 32 μm diameter device is 7 GHz. This work proves that InGaAs buffer layers grown by solid source MBE are promising candidates for GaAs-based long wavelength devices.
基金Project supported by the National Natural Science Foundation of China(Nos.10734060,90921015)the National Basic Research Program of China(Nos.2007CB936304,2010CB327601)
文摘Molecular beam epitaxy growth of a bilayer stacked InAs/GaAs quantum dot structure on a pure GaAs matrix has been systemically investigated.The influence of growth temperature and the InAs deposition of both layers on the optical properties and morphologies of the bilayer quantum dot（BQD） structures is discussed.By optimizing the growth parameters,InAs BQD emission at 1.436μm at room temperature with a narrower FWHM of 27 meV was demonstrated.The density of QDs in the second layer is around 9×10~9 to 1.4×10^（10） cm^（-2）. The BQD structure provides a useful way to extend the emission wavelength of GaAs-based material for quantum functional devices.
基金Project supported by the National Natural Science Foundation of China (Grant Nos. 61176012 and 90921015)the National Basic Research Program of China (Grant Nos. 2010CB327601 and 2012CB932701)the National Science Foundation for Post-doctoral Scientists of China (Grant No. 20080440507)
文摘The solar spectrum covers a broad wavelength range, which requires that antireflection coating （ARC） is effective over a relatively wide wavelength range for more incident light coming into the cell. In this paper, we present two methods to measure the composite reflection of SiO2/ZnS double-layer ARC in the wavelength ranges of 300-870 nm （duaI- junction） and 300-1850 nm （triple-junction）, under the solar spectrum AM0. In order to give sufficient consideration to the ARC coupled with the window layer and the dispersion effect of the refractive index of each layer, we use multidimensional matrix data for reliable simulation. A comparison between the results obtained from the weighted-average reflectance （WAR） method commonly used and that from the effective-average reflectance （EAR） method introduced here shows that the optimized ARC through minimizing the effective-average reflectance is convenient and available.
基金Supported by the National Natural Science Foundation of China under Grant Nos 60876039 and 61176053the Hi-Tech Research and Development Program of China(863 Program)under Grant No 2009AA03Z404the National Basic Research Program of China(973 Program)under Grant No 2010CB327601.
文摘Tunable metamorphic InGaAs partially depleted absorber photodiodes with resonant cavity enhanced structure are fabricated on GaAs substrate.Dark-current densities of 7.2×10^(-7)A/cm^(2) at 0 V and 3.6×10^(-4)A/cm^(2) at-5 V,a high quantum efficiency of 74.4%at 1546nm,and a 3-dB bandwidth up to 12GHz are achieved.The full width at half maximum of the detector is about 16nm.Furthermore,through thermal tuning,the peak wavelength red shifts from 1527nm to 1544 nm,and a tuning range of 17nm is realized without fabricating extra tuning electrodes.
基金supported by the National Natural Science Foundation of China (Nos.90921015 and 10734060)the National Basic Research Program of China (No.2010CB327601)
文摘The GaAs based InGaAs metamorphic structures and their growth by molecular beam epitaxy (MBE) are investigated. The controlling of the source temperature is improved to realize the linearly graded InGaAs metamorphic structure precisely. The threading dislocations are reduced. We also optimize the growth and annealing parameters of the InGaAs quantum well (QW). The 1.3-μm GaAs based metamorphic InGaAs QW is completed. A 1.3-μm GaAs based metamorphic laser is reported.
基金Supported by the National Natural Science Foundation of China under Grant No 60625405the National Basic Research Program of China under Grant Nos 2007CB936304 and 2010CB327601the China Postdoctoral Science Foundation under Grant No 20080440507.
文摘According to the theory of optical films,we simulate the reflectivity of antireflection coatings(ARCS)for solar cells of Gao.51no.5P/GaAs/Ge based on an optical transfer matrix.In order to provide sufficient consideration of the refractive index dispersion effect of multilayer ARCS,we use multi-dimensional matrix data for reliable simulation.After the reflection curves are obtained,the effective average reflectance Re is introduced to optimize the film system by minimizing Re.Optimization of single layer(A1_(2)0_(3)),double layer(MgF_(2)/ZnS)and triple layer(MgF_(2)/A1_(2)0_(3)/ZnS)ARCS is realized by using this method for space and terrestrial applications.Effects of these ARCS are compared after optimization.These theoretical parameters can be used to guide experiments.
基金Project supported by the National Natural Science Foundation of China(Grant No.60625405)the National Basic Research Program of China(Grant Nos.2007CB936304 and 2010CB327601)
文摘Molecular beam epitaxy growth of GaAs on an offcut Ge （100） substrate has been systemically investigated. A high quality GaAs/Ge interface and CaAs film on Ge have been achieved. High temperature annealing before GaAs deposition is found to be indispensable to avoid anti-phase domains. The quality of the GaAs film is found to strongly depend on the GaAs/Ge interface and the beginning of GaAs deposition. The reason why both high temperature annealing and GaAs growth temperature can affect epitaxial GaAs film quality is discussed. High quality InonTGao.s3As/GaAs strained quantum wells have also been achieved on a Ge substrate. Samples show flat surface morphology and narrow photoluminescence line width compared with the same structure sample grown on a GaAs substrate. These results indicate a large application potential for Ⅲ-Ⅴcompound semiconductor optoelectronic devices on Ge substrates.
