Si/Ge nanostructures for optoelectronics applications

The optical and structural properties of multilayer Si/Ge structures with precritical, as well as close-to-critical, germanium inclusions in a silicon matrix, for which the transition from the two-dimensional to island growth occurs, were studied. The possibility of obtaining intense photoluminescence at room temperature in both cases under optimally chosen growth parameters is demonstrated. The proposed approaches to producing an active region appear promising for applications in silicon-based optoelectronics.     

Fabrication and optical properties of self-assembled InAsSb/InP nanostructures on InP (001) substrate

This article presents a study on the growth and optical properties of self-assembled InAsSb/InP nanostructures on (001) InP substrate, which are potential candidate materials for making mid-infrared lasers. The surfactant effect of Sb atoms is found to play a crucial role in the formation of flat InAsSb quantum dashes with almost identical island width no matter the change of InAsSb deposition thickness. The critical thickness for the transition from two-dimensional plane growth to three-dimensional island growth is observed to be less than two monolayer. And the photoluminescence measurements on InAsSb quantum dashes with different nominal Sb composition well demonstrate the band-gap bowing effect induced by the incorporation of Sb atoms into InAs quantum dots. The photoluminescence linewidth of InAsSb quantum dashes also present unusual temperature behavior, which can be attributed to the narrow size distribution of InAsSb quantum dashes.     

Novel nanostructures of ZnO for nanoscale photonics,optoelectronics, piezoelectricity,and sensing

Wurtzite-structured semiconductors such as ZnO, GaN, AlN, CdSe and ZnS are important materials for nanoscale devices. Zinc oxide, for example, is a unique material that exhibits semiconducting, piezoelectric, and pyroelectric properties. Using a solid–vapor phase thermal sublimation technique, nanocombs, nanorings, nanohelixes/nanosprings, nanobows, nanobelts, nanowires, and nanocages of ZnO have been grown under specific growth conditions. This paper is about the synthesis, structure, growth mechanisms, and potential applications of these nanostructures in optoelectronics, sensors, transducers, and biomedical science. PACS 81.07.-b; 78.67.-n; 85.35.-p     

Detectors for monolithic optoelectronics

In this paper, we present data on the electrical characteristics and the optical response of photodetectors integrated on GaAs substrates with FET devices. We compare the differences between devices fabricated on globally implanted areas versus the undoped semi-insulating regions of the same wafer.     

Detectors for monolithic optoelectronics

In this paper, we present data on the electrical characteristics and the optical response of photodetectors integrated on GaAs substrates with FET devices. We compare the differences between devices fabricated on globally implanted areas versus the undoped semi-insulating regions of the same wafer.     

A dual-polarization InSb receiver for 461/492 GHz

A dual-polarization InSb hot-electron bolometer-mixer receiver has been built for the James Clerk Maxwell Telescope, for operation at 461 and 492 GHz (the frequencies of theJ=43 rotational transition of CO and of the³ P ₁³ P ₀ transition of neutral carbon). Receiver noise temperatures of 500K have been obtained at 461 GHz, in observing bandwidths of 3 MHz. The receiver was designed as a common-user or facility instrument. Here we describe those aspects of the design and construction which enabled this goal to be realized.     

InAsSb/InAsSbP current-tunable laser with narrow spectral line width

The article describes the manufacture and testing of a new type of semiconductor laser working at low temperatures (12–100 K) in the wavelength range 3200–3300 cm^-1. This kind of laser can be tuned in the modal range up to 6 cm^-1 and is characterized by a narrow spectral line width (about 7 MHz). Received: 12 September 2002 / Final version: 29 January 2003 / Published online: 22 May 2003 RID="*" ID="*"Corresponding author. Fax: +420-286/591-766, E-mail: civis@jh-inst.cas.cz     

Quantum wells for femtosecond optoelectronics applications

The ultrafast nonlinear optical properties of quantum well excitons have been studied extensively in recent years. Quantum well excitons, which are sharp and well-resolved at room temperature, are well suited to optoelectronics applications, having large electroabsorption response. In this review, we discuss experiments which use simultaneously the nonlinear optical response of the quantum well exciton and the electroabsorption response in order to characterize electrical signals in the femtosecond time scale. In addition, we discuss intrinsic speed limitations in excitonic optoelectronics and extensions to one- and two-dimensional spatiotemporal field mapping.     

Organic polymer p-n heterostructures for optoelectronics

The photovoltaic effect due to the photogeneration of charge carriers at the interface in organic polymeric p-n-heterostructures based on the developed composites with hole (doped polyimides, conjugated polymers) and electron (doped polyetherimides and carbazolyl-containing polymers) conduction was observed and studied. The best performance was observed for heterostructures with diffuse and developed (bulk) interface. The maximum energy conversion efficiency was found to be 0.5% at λ = 400–650 nm. Components with enhanced photo and thermal stability were used. A weak photovoltaic effect was observed for heterostructures based on conjugated polymers (with a sharp interface). In this case, the rectification (diode) effect was observed for both dark current and photocurrent due to dark and photo injection of carriers from the electrodes at bias voltages across the cell above the injection threshold (V > V _i ). This conclusion is supported by the observation of recombination electroluminescence of the dopant in the n-layer, indicating a full or partial recombination of carriers at the interface. At V < V _i , photocurrent under reverse bias (+A1, ?ITO) is significantly higher than that under forward bias due to an efficient photogeneration of carriers at the interface and separate transport thereof. A sensitivity of about 100 mA/W at λ = 400–500 nm was reached.     

Advances in wide bandgap SiC for optoelectronics

Silicon carbide (SiC) has played a key role in power electronics thanks to its unique physical properties like wide bandgap, high breakdown field, etc. During the past decade, SiC is also becoming more and more active in optoelectronics thanks to the progress in materials growth and nanofabrication. This paper will review the advances in fluorescent SiC for white light-emitting diodes, covering the poly-crystalline doped SiC source material growth, single crystalline epitaxy growth of fluorescent SiC, and nanofabrication of SiC to enhance the extraction efficiency for fluorescent SiC based white LEDs.     

An integrated organic photoconductive detector for optoelectronics

In the system (poly-(N-vinyl carbazole) (PVK): trinitrofluorenone (TNF) a photoconductive complex is formed. Thin metal films are sputtered on BK7 glass substrates, forming two electrodes with 1 mm separation. The photoconductive complex is deposited from a solution in chlorobenzene/tetrahydrofurane on the glass substrate between the electrodes, forming a photoconductive detector. Photoconductivity of these planar detectors is studied using He-Ne laser light (=633 nm) as a function of electric field and for different TNF concentrations. An increase of photosensitivity is found for high TNF concentrations.Time resolution of the photoconductive PVK:TNF detector is investigated using a ruby pulse laser (=694 nm). The possible use of such detectors in combination with other polymer lightguides is demonstrated. Compared to most polymer waveguide materials PVK exhibits a rather high refractive index ofn=1.7. Thus the coupling of light into the photoconductive film is achieved directly. The planar structure allows further integration of polymeric components for optoelectronics.     

Optical transitions in strained InAsSb/GaInSb interband QC lasers

In this paper a detailed simulation and theoretical analysis based on model-solid theory and the(→κ)·(→ρ)methodare presented to investigate the dependence of the band structure on the strain deformation in a noveltype-Ⅱ quantum well(QW)heterostructure InAs1_ySby/GaxIn1-xSb under the uniaxial approximation,and subsequently the optical transition and the gain in the interband cascade lasers containing it havebeen evaluated with unchanged injection current densities.The simulation results show that the straineffect on the transition in this heterostructure will not behave as a simple monotonic trend with the latticemismatch of InAs1_ySby/GaxIn1_xSb interface,but as a function of the complex strain chain includingthe whole active region.It is important to the subsequent device design and optimization.     

中红外光参变振荡器在高反射率测量中的应用

根据光腔衰荡光谱技术(CRDS)原理,使用中红外光参变振荡器(OPO)为光源建立了直腔与折叠腔相结合的中红外波段3.6 μm 反射率测量实验装置,用于研究中红外波段的高反射膜反射率,测试精度为10-4。使用直型衰荡光腔测试了三对不同薄膜材料设计镀制的高反射腔镜的反射率,并选择了一对腔镜用于实验装置中。采用该装置精确测试了不同薄膜材料镀制的高反射膜的反射率,包括YbF3/ZnS,YbF3 /ZnSe多层膜,以及由银加保护膜镀制的反射镜。研究表明,中红外波段介质膜的反射率可达到R>0.9990,其中由YbF3/ZnSe镀制在硅基底上的多层介质膜3.6 μm反射率可达到99.96％。     

Study of Single-Electron Spectrum of GaAs/AlGaAs Heterostructure for Mid-IR Photodetectors via Low-Temperature Luminescence

Bulletin of the Lebedev Physics Institute - By measuring low-temperature photoluminescence, we demonstrated the role of interface blurring and the introduction of background impurities in the...     

InSb/CdTe heterostructures grown by MBE

InSb/CdTe heterostructures were grown by MBE, including a 10 layer superlattice. The structures were characterized by X-ray diffraction, van der Pauw measurements, and SNMS depth profiling. The interfaces widen because of interdiffusion and through the formation of an interface compound from the reaction of Te with the InSb surface. The interface compound is identified as strained InTe(II). The interfaces are still too wide for practical devices. Thermochemical analysis indicates that the reaction can be suppressed by applying a Cd overpressure. The diffusion of In and Sb in CdTe is very fast and will necessitate a MEE growth scheme at lower temperatures.     

Forming a Type-II Heterojunction in the InAsSb/InAsSbP Semiconductor Structure

Physics of the Solid State - We report on the electroluminescent and I–V characteristics of the n-InAs/n-InAsSb/p-InAsSbP heterostructure grown by metalorganic vapor-phase epitaxy. In the...     

Performance limits of the mid-wave InAsSb/AlAsSb nBn HOT infrared detector

InAsSb ternary alloy is considered to be an alternative to HgCdTe (MCT) in mid-wavelength infrared spectral region. The high operation temperature conditions are successfully reached with $\hbox {A}^{\mathrm{III}}\hbox {B}^{\mathrm{V}}$ bariodes, where InAsSb/AlAsSb system is playing dominant role. Since there is no depletion region in the active layer, the generation-recombination and trap-assisted tunneling mechanisms are suppressed leading to lower dark currents in comparison with standard photodiodes. As a consequence, the bariodes operate at a higher temperature than standard photodiodes which could be used in wide range of system applications, especially where the size, weight, and power consumption are crucial. The paper presents detailed analysis of the bariode’s performance (such as dark and photocurrent, differential resistance area product, and detectivity) versus applied voltage, operating temperatures and structural parameters. The optimal working conditions are calculated. The theoretical predictions of bariode’s performance are compared with experimental data published in the literature. Finally, the nBn InAsSb/AlAsSb performance is compared to the MCT “Rule 07”.