Successive ion layer adsorption and reaction (SILAR) originally developed for the deposition of thin films on solid substrates from solution baths is introduced as a technique growth high-quality core/shell nanocrystals compound semiconductors. The shell was designed to grow one monolayer at time by alternating injections air-stable inexpensive cationic anionic precursors into mixture with core nanocrystals. principles SILAR were demonstrated CdSe/CdS model system using its...

Type II CdSe/CdTe core/shell nanocrystals with a dot shape were synthesized using modified SILAR technique that incorporates cycling of the reaction temperature (thermal cycling). Conversely, experimental results revealed standard alone produced type in peanut (1D). Despite their differences shape, optical properties observed for dot- and peanut-shaped similar. The dot-shaped confirmed as structures an abrupt heterojunction within accuracy, ones found to be consistent CdSe CdTe separated on...

A photovoltaic (PV) device based on an interband cascade (IC) structure is proposed for efficiently converting solar and thermal energy to electricity. These IC PV devices employ absorption transport regions with characteristics that are favorable achieving high open-circuit voltage thus possibly improving conversion efficiency over conventional devices. Preliminary experiments carried out using infrared photodetectors (seven stages) lasers (11 showed voltages exceed the single-band gap from...

InAs-based interband cascade (IC) lasers with improved optical confinement have achieved high-temperature operation a threshold current density as low 247 A/cm2 at 300 K for emission near 4.6 μm. The is the lowest ever reported among semiconductor mid-infrared similar wavelengths. These IC devices lased in pulsed mode temperatures up to 377 5.1 Narrow-ridge were able operate continuous-wave 308 4.8 implications and prospects of these results are discussed.

The high-frequency operation of a mid-infrared interband cascade system that consists type-I laser and an uncooled infrared photodetector (ICIP) is demonstrated at room temperature. 3-dB bandwidth this under direct frequency modulation was ∼850 MHz. A circuit model developed to analyze the characteristics. extracted for ICIP ∼1.3 GHz, signifying great potential structures high-speed applications. normalized Johnson-noise-limited detectivity these ICIPs exceeded 109 cm Hz1/2/W 300 K. These...

InAs/AlAs$_{x}$Sb$_{1-x}$ quantum wells are investigated for their potential as hot carrier solar cells. Continuous wave power and temperature dependent photoluminescence indicate a transition in the dominant relaxation process from conventional phonon-mediated below 90 K to regime where inhibited radiative recombination dominates at elevated temperatures. At temperatures measurements consistent with type-I that exhibit hole localization associated alloy/interface fluctuations....

Formation of Mn2+-doped ZnSe quantum dots (Mn:ZnSe d-dots) with both branched and nearly spherical shapes has been studied. Structure analysis indicates that the Mn2+ dopants were localized in core a nanocrystal. The growth d-dots, rather than ones, was achieved by simply varying concentration two organic additives, fatty acids, amines. photoluminescence properties nanocrystals explored compared those particles.

In order to achieve improved understanding and gain insights into the device operation of interband cascade infrared photodetectors (ICIPs) ultimately optimize design, we present a comparative study five long-wavelength (LW) ICIPs based on type-II InAs/GaSb superlattice. This shows how responsivity is affected by individual absorber thicknesses number stages, through impact light attenuation. Additionally, this further validates that electrical universally exists in non-current-matched...

We report on a comparison study of long wavelength infrared interband cascade photodetectors (ICIPs) with the goal an improved understanding that will lead to further increases in operation temperature. studied four sets detectors including single absorber barrier and multi-stage ICIPs four, six, eight discrete absorbers. The 90% cutoff these was between 7.5 11.5 μm from 78 340 K. Multiple stage were able operate monotonically increasing bias-independent responsivity up 280 K, while...

One of the main loss mechanisms in photovoltaic solar cells is thermalization photogenerated hot carriers via phonon-mediated relaxation. By inhibiting these relaxation and reducing losses, it may be possible to improve power conversion efficiency beyond single gap limit. Here, type-II InAs/AlAsSb multi-quantum well (MQW) structures are investigated study impact phononic properties AlAsSb barrier material carrier thermalization. Experimental theoretical results show that by increasing...

We have fabricated and characterized surface-emitting, spin-polarized light-emitting diodes with a Mn-doped InAs dilute magnetic quantum dot spin-injector contact region grown by low-temperature molecular beam epitaxy, an In0.4Ga0.6As active region. Energy-dispersive X-ray electron energy loss spectroscopies performed on individual dots indicate that the Mn atoms incorporate within themselves. Circularly polarized light is observed up to 160 K maximum degree of circular polarization 5.8%...

We report on a comparison study of the electrical and optical properties set device structures with different numbers cascade stages, type-II superlattice (T2SL) absorber thickness, doping variations, as well noncurrent-matched interband infrared photodetectors (ICIP) structure equal absorbers. Multistage ICIPs were demonstrated to be capable operating at high temperatures zero-bias superior carrier transport over comparable conventional one-stage detectors. Based temperature dependence bias...

Abstract Detection and characterization of a different type topological excitations, namely the domain wall (DW) skyrmion, has received increasing attention because DW is ubiquitous from condensed matter to particle physics cosmology. Here we present experimental evidence for skyrmion as ground state stabilized by long-range Coulomb interactions in quantum Hall ferromagnet. We develop an alternative approach using nonlocal resistance measurements together with local NMR probe measure effect...

We present a single-step, electrochemical approach to the growth and low contact resistance interconnecting of gold nanowires with targeted points on lithographic electrodes. Electron diffraction studies indicate that these are composed face-centred cubic crystalline gold, crystal structure is invariant along wire lengths. Four-point determinations electrode?nanowire?electrode assemblies consistently yield resistances <50??, contributions from electrode?wire contacts order 10??. Atomic force...

The optimal conditions for growth of homoepitaxial InAs layers by molecular beam epitaxy were investigated over a wide range substrate temperatures and As2/In flux ratios at rate 0.66 monolayer/s. Material quality was using variety techniques: differential interference contrast microscopy, scanning electron atomic force microscopy. results indicated that the layer grown temperature between 430 450 °C with an ratio about 15:1 yielded highest quality, defect density 2 × 104 cm−2 root mean...

We report on a comparative study of two sets different long-wavelength (LW) interband cascade infrared photodetectors (ICIPs) based type-II InAs/GaSb superlattice. The devices in one set have current-matched configuration while those the other are non-current-matched. It is shown that carrier transport these LW ICIPs at high temperatures diffusion limited and length estimated to be longer than or comparable 0.5 μm various temperatures. By comparing devices, we demonstrate necessity...

Electrically tunable interband cascade lasers are demonstrated with a wide tuning range of about 280 cm−1 (34 meV in energy or 630 nm wavelength) near 4.5 μm and 180 (22 900 nm) 7 wavelengths. The laser structures designed such that the heating Stark effects act together to enhance red-shift lasing wavelength current injection achieve tunability. control manipulation rate discussed.

InAs-based interband cascade (IC) lasers with dielectric-metal hybrid top cladding layers were demonstrated at emission wavelengths near 5.3 μm for temperatures up to 248 K in continuous wave mode and 300 pulsed mode. Preliminary experimental results showed that these waveguide IC had slightly better device performances terms of operating temperature, compared InAs plasmon on both sides. The threshold current densities as low 12 A/cm <sup xmlns:mml="http://www.w3.org/1998/Math/MathML"...

Interband cascade (IC) lasers take advantage of the broken band-gap alignment in type-II quantum wells to reuse injected electrons stages for photon generation with high efficiency, while retaining interband transitions emission without involving fast phonon scattering. As such, threshold current density can be significantly lowered voltage resulting low power consumption. After about 18 years exploration and development, IC have now been proven capable continuous wave operation at room...

We report the first implementation of an advanced waveguide structure, consisting GaSb separate confinement layers, n-doped InAs/AlSb superlattice intermediate cladding and n + -doped InAs0.91Sb0.09 plasmon-enhanced layers for GaSb-based interband cascade lasers (ICLs) with lasing wavelengths in 3 to 4 μm wavelength region. This configuration ICLs can have improved thermal dissipation enhanced optical confinement. Although grown ICL wafers had significant layer thickness deviations from...