Luminescence of II–VI and III–V nanostructures
Abstract: Photoluminescence of HgCdTe epitaxial films and nanostructures and electroluminescence of InAs(Sb,P) light-emitting diode (LED) nanoheterostructures were studied. For HgCdTe-based structures, the presence of compositional fluctuations, which localized charge carriers, was established. A model, which described the effect of the fluctuations on the rate of the radiative recombination, the shape of luminescence spectra and the position of their peaks, was shown to describe experimental photoluminescence data quite reasonably. For InAs(Sb,P) LED nanoheterostructures, at low temperatures (4.2–100 K) stimulated emission was observed. This effect disappeared with the temperature increasing due to the resonant ‘switch-on’ of the Auger process involving transition of a hole to the spin-orbit-splitted band. Influence of other Auger processes on the emissive properties of the nanoheterostructures was also observed. Prospects of employing II–VI and III–V nanostructures in light-emitting devices operating in the mid-infrared part of the spectrum are discussed.
Citations
More filters
TL;DR: In this paper, pure and Ni-doped ZnO nanostructures (NSs) with different concentrations of Ni (2, 4, 6%) were successfully prepared via solution combustion method.
Abstract: In this work, pure and Ni-doped ZnO nanostructures (NSs) with different concentrations of Ni (2, 4, 6%) were successfully prepared via solution combustion method. The TEM photograph shows the formation of flake-like structures with the decrease in size of NSs as the dopant concentration is increased. XRD investigation shows the hexagonal wurtzite structure of doped and undoped ZnO nanostructures with a NiO peak (200) as secondary phase for 4 and 6% dopant concentration level. Broadening of spectra of ZnO around 480 cm−1 in FTIR spectra is observed with the increase of dopant concentration. UV–Visible spectra show the increase in absorbance when the dopant level (Ni2+) is increase from 2 to 4% in ZnO and decrease in absorbance with further increase in dopant level to 6%. An increase in energy band gap is observed in Ni (6%)-doped ZnO due to due to the sp–d interactions taking place between the band electrons and the localised d electrons of Ni2+ ions (Burstein-Moss effect). I–V characteristics reveal the increase in current with the increase in dopant level from 2 to 4% and decrease in current when the dopant level is further increased to 6% which is in agreement with the Burstein-Moss effect.
10 citations
TL;DR: In this paper, an ab initio study of the electronic and magnetic properties of CdS doped by the transition metal elements has been investigated based on the KKR-CPA method within the Generalized Gradient Approximation (GGA).
Abstract: In this paper, an ab initio study of the electronic and magnetic properties of CdS doped by the transition metal elements has been investigated. Based on the KKR-CPA method within the Generalized Gradient Approximation (GGA), we have calculated the total energy to determine the most stable state in the system and found it to be the ferromagnetic state for Ti, V and Cr-doped CdS, while it is the stabilization in spin glass states for Mn and Co cases. On the other hand, we have investigated and plotted the density of states (DOSs) which reveals that the doped compounds exhibit a half-metallic character. The spin polarization at Fermi level is estimated and found to be around 100%. Furthermore, we have identified the type of mechanism of exchange interactions being double exchange for all components except Mn case where we find that the responsible mechanism is the p-d exchange. The evaluation of the Curie temperature variation TC for the three components stable in the ferromagnetic phase revealed values greater than 300 K for most cases. The effect of the crystal field and the exchange splitting as a function of the concentrations values has been also investigated. Half-metallic substances are very interesting for spin-dependent electronics devices as they boost their magnetoresistance capacity.
10 citations
TL;DR: ZnS/CdS1-xSex nancomposite has been obtained by a two-step process as mentioned in this paper, where CdS 1-xS nanoparticles are prepared by one-pot hydrothermal method, and then the Cds 1-XS is dispersed in Zn(NH3)42+ solution, and dropping with Na2S solution, resulting in the ZnS and Cds1-sex shell/core nanocomposite.
6 citations
TL;DR: In this paper, the authors investigated the optimum conditions of preparing CdS1-xSex conventional materials with high crystallinity and strong photoluminescence and found that the composition, structure, and photoluminance strongly depend on the reaction temperature, pH of reaction medium, and CS(NH2)2/CdCl2 molar ratio.
6 citations
TL;DR: In this paper, a simple chemical vapor deposition using Ga2O3 and NH3 as precursors was used to synthesize GaN nanostructures, and the configuration of GaN nano-structures was found to be strongly dependent on the growth temperature and the NH3 flow rate.
2 citations
References
More filters
TL;DR: In this article, the authors present a comprehensive, up-to-date compilation of band parameters for the technologically important III-V zinc blende and wurtzite compound semiconductors.
Abstract: We present a comprehensive, up-to-date compilation of band parameters for the technologically important III–V zinc blende and wurtzite compound semiconductors: GaAs, GaSb, GaP, GaN, AlAs, AlSb, AlP, AlN, InAs, InSb, InP, and InN, along with their ternary and quaternary alloys. Based on a review of the existing literature, complete and consistent parameter sets are given for all materials. Emphasizing the quantities required for band structure calculations, we tabulate the direct and indirect energy gaps, spin-orbit, and crystal-field splittings, alloy bowing parameters, effective masses for electrons, heavy, light, and split-off holes, Luttinger parameters, interband momentum matrix elements, and deformation potentials, including temperature and alloy-composition dependences where available. Heterostructure band offsets are also given, on an absolute scale that allows any material to be aligned relative to any other.
6,349 citations
TL;DR: A review of the history, the present status and possible future developments of HgCdTe ternary alloy for infrared (IR) detector applications is presented in this article.
Abstract: This article reviews the history, the present status and possible future developments of HgCdTe ternary alloy for infrared (IR) detector applications. HgCdTe IR detectors have been intensively developed since the first synthesis of this material in 1958. This article summarizes the fundamental properties of this versatile narrow gap semiconductor, and relates the material properties to its successful applications as an IR photoconductive and photovoltaic detector material. An emphasis is put on key developments in the crystal growth and their influence on device evolution. Competitive technologies to HgCdTe ternary alloy are also presented. Recent advances of backside illuminated HgCdTe heterojunction photodiodes have enabled a third generation of multispectral instruments for remote sensing applications and have led to the practicality of multiband IR focal plane array technology. Finally, evaluation of HgCdTe for room temperature long wavelength IR applications is presented. (Some figures in this article are in colour only in the electronic version)
806 citations
01 Jan 2006
TL;DR: In this article, the theory of mid-wavelength infrared laser active regions is discussed, including properties and design strategies for mid-infrared active regions, as well as the application of these regions for gas detection.
Abstract: Part I: Materials and Device Design Considerations- Theory of Mid-Wavelength Infrared Laser Active Regions: Intrinsic Properties and Design Strategies- Bandstructure and High-pressure Measurements- Part II: Lasers- III-Sb-based Type-I QW Diode Lasers- VCSELs Emitting in the 2 - 3 m Wavelength Range- Antimonide Type-II 'W' Lasers- Interface Lasers with Asymmetric Band Offset Confinement- IV-VI Semiconductors for Mid-Infrared Optoelectronic Devices- Mid-infrared Vertical Cavity Surface Emitting Lasers based on the Lead Salt Compounds- Optically Pumped MIR Lasers- Mid-infrared Quantum Cascade Lasers- Part III: Detectors- Mid-infrared Electroluminescence in LEDs Based on InAs and Related Alloys- LED-Photodiode Opto-pairs- QWIP Detectors for the MWIR- Negative Luminescence- Mid-Infrared Quantum Dot Photodetectors- Quantum Photovoltaic Devices Based on Antimony Compound Semiconductors- High-speed Avalanche Photodiodes for the 2-5 m Spectral Range- Part IV: Applications- Infrared Methods for Gas Detection- Mid-infrared Biomedical Applications- The Development of Infrared Countermeasure Technology and Systems- Survey of Thermophotovoltaic (TPV) Devices
192 citations
TL;DR: In this paper, the authors considered a set of physical phenomena occurring during epitaxial growth, including coupling that exists between the various effects, and concluded that several separate mechanisms exist for phase separation.
156 citations
TL;DR: In this paper, it has been shown by means of the envelope function approximation using the full $8\ifmmode\times\else\texttimes\fi{}8$ Kane Hamiltonian, that the valence band offset is primarily responsible for the separation between the $H1\ensuremath{-}E1$ and $L1\ENSuremath{\Lambda} intersubband transition energies of semiconducting superlattices and their dependence on temperature.
Abstract: Intersubband transitions in ${\mathrm{H}\mathrm{g}\mathrm{T}\mathrm{e}/\mathrm{H}\mathrm{g}}_{1\ensuremath{-}x}{\mathrm{Cd}}_{x}\mathrm{Te}$ superlattices and their dependence on temperature have been investigated for a large number of superlattices with widely different parameters. It has been shown by means of the envelope function approximation using the full $8\ifmmode\times\else\texttimes\fi{}8$ Kane Hamiltonian, that the valence band offset is primarily responsible for the separation between the $H1\ensuremath{-}E1$ and $L1\ensuremath{-}E1$ intersubband transition energies of semiconducting ${\mathrm{H}\mathrm{g}\mathrm{T}\mathrm{e}/\mathrm{H}\mathrm{g}}_{1\ensuremath{-}x}{\mathrm{Cd}}_{x}\mathrm{Te}$ superlattices with a normal band structure. To a good approximation, all other relevant superlattice parameters have little or no effect on this energy difference. This leads to an unequivocal determination of the valence band offset between HgTe and CdTe \ensuremath{\Lambda} which is $570\ifmmode\pm\else\textpm\fi{}60\mathrm{meV}$ at 5 K for both the (001) and the $(112)\mathrm{B}$ orientations. The temperature dependence of both intersubband transition energies can only be explained by the following conditions: \ensuremath{\Lambda} is also temperature dependent as expressed by $d\ensuremath{\Lambda}/dT=\ensuremath{-}0.40\ifmmode\pm\else\textpm\fi{}0.04\mathrm{m}\mathrm{e}\mathrm{V}/\mathrm{K};$ the anisotropic heavy hole effective mass has a significant temperature dependence; and ${E}_{g}(\mathrm{HgTe},300\mathrm{K})=\ensuremath{-}160\ifmmode\pm\else\textpm\fi{}5\mathrm{meV}$ which is appreciably lower than the extrapolated values found in the literature.
74 citations