Introduction to Semiconductor Heterojunctions

Milnes, A. G.; Feucht, D. L.

doi:10.1016/b978-0-12-498050-1.50007-6

Cited by 110 publications

(74 citation statements)

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“…This leads to A j Cd = 12µeV. Taking the CdSe lattice constant a 0 ≈ 4.2Å [27] we calculate N L = 3, 500 for the ground 1S electron state in spherical nanocrystals with a radius 28Å. Only 1/8 of these nuclei contribute to dephasing.…”

Section: Discussionmentioning

confidence: 99%

Electron spin relaxation by nuclei in semiconductor quantum dots

2002

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We have studied theoretically the electron spin relaxation in semiconductor quantum dots via interaction with nuclear spins. The relaxation is shown to be determined by three processes: (i) -the precession of the electron spin in the hyperfine field of the frozen fluctuation of the nuclear spins; (ii) -the precession of the nuclear spins in the hyperfine field of the electron; and (iii) -the precession of the nuclear spin in the dipole field of its nuclear neighbors. In external magnetic fields the relaxation of electron spins directed along the magnetic field is suppressed. Electron spins directed transverse to the magnetic field relax completely in a time on the order of the precession period of its spin in the field of the frozen fluctuation of the nuclear spins.Comparison with experiment shows that the hyperfine interaction with nuclei may be the dominant mechanism of electron spin relaxation in quantum dots.

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Section: Discussionmentioning

confidence: 99%

Electron spin relaxation by nuclei in semiconductor quantum dots

2002

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“…One possibility is that this transition occurs due to interface states, which would be expected for a heterojunction with lattice mismatch exceeding 1%. 52 Furthermore, low energy emission band (1.9-2.7 eV) observed in nitride tunneling diodes was attributed to tunneling and found to be related to the high electric field strength. 49 Thus, under reverse bias, tunneling of the electrons occurs from pGaN to ZnO resulting in the appearance of holes in the pGaN.…”

Section: The Origin Of the Emission Peaksmentioning

confidence: 99%

“…[48][49][50][51] Furthermore, since the lattice mismatch between GaN and ZnO is higher than 1%, interface states are expected to significantly affect the current flow across the junction and severely limit the injection of the minority carriers. 52 Thus, significant current transport mechanisms in these devices are expected to involve tunneling and recombination at the interface, 52 and the tunneling likely involves the defect states at the interface, as illustrated in Fig. 1(b).…”

Section: B Performance Under Reverse Biasmentioning

confidence: 99%

ZnO nanorod/GaN light-emitting diodes: The origin of yellow and violet emission bands under reverse and forward bias

Chen

Fang

et al. 2011

Journal of Applied Physics

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Study of droop phenomena in InGaN-based blue and green light-emitting diodes by temperature-dependent electroluminescence Appl. Phys. Lett. 100, 153506 (2012) Silicon-nanocrystal resonant-cavity light emitting devices for color tailoring J. Appl. Phys. 111, 074512 (2012) Effects of energetic disorder on the low-frequency differential capacitance of organic light emitting diodes J. Appl. Phys. 111, 074506 (2012) Probing the electrode-polymer interface in conjugated polymer devices with surface-enhanced Raman scattering Appl. Phys. Lett. 100, 141907 (2012) Low-cost caesium phosphate as n-dopant for organic light-emitting diodes J. Appl. Phys. 111, 074502 (2012) Additional information on J. Appl. Phys. ZnO nanorods have been prepared by electrodeposition under identical conditions on various p-GaN-based thin film structures. The devices exhibited lighting up under both forward and reverse biases, but the turn-on voltage and the emission color were strongly dependent on the p-GaN-based structure used. The origin of different luminescence peaks under forward and reverse bias has been studied by comparing the devices with and without ZnO and by photoluminescence and cathodoluminescence spectroscopy. We found that both yellow-orange emission under reverse bias and violet emission under forward bias, which are commonly attributed to ZnO, actually originate from the p-GaN substrate and/or surface/interface defects. While the absolute brightness of devices without InGaN multiple quantum wells was low, high brightness with luminance exceeding 10 000 cd/m 2 and tunable emission (from orange at 2.1 V to blue at 2.7 V, with nearly white emission with Commission internationale de l'éclairage (CIE) coordinates (0.30, 0.31) achieved at 2.5 V) was obtained for different devices containing InGaN multiple quantum wells.

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“…5 (20,28). The band diagram clearly indicates how the large discontinuity in the valence band at the Se 97 S 3 ∕ZnS3 interface would create a barrier to hole flow, and the estimated valence band discontinuity between Se 97 S 3 and ZnSe of 0.7 eV is nearly equal to the observed built-in voltage of 0.8 eV.…”

Section: Determined By Both C-v and Kpfm Measurementsmentioning

confidence: 70%

Fiber draw synthesis

Orf

Shapira²,

Sorin

et al. 2011

Proc. Natl. Acad. Sci. U.S.A.

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The synthesis of a high-melting temperature semiconductor in a low-temperature fiber drawing process is demonstrated, substantially expanding the set of materials that can be incorporated into fibers. Reagents in the solid state are arranged in proximate domains within a fiber preform. The preform is fluidized at elevated temperatures and drawn into fiber, reducing the lateral dimensions and bringing the domains into intimate contact to enable chemical reaction. A polymer preform containing a thin layer of selenium contacted by tin-zinc wires is drawn to yield electrically contacted crystalline ZnSe domains of sub-100-nm scales. The in situ synthesized compound semiconductor becomes the basis for an electronic heterostructure diode of arbitrary length in the fiber. The ability to synthesize materials within fibers while precisely controlling their geometry and electrical connectivity at submicron scales presents new opportunities for increasing the complexity and functionality of fiber structures.flexible electronics | optical fiber processing | semiconductor device T hermal fiber drawing is a process in which a macrostructured preform is heated and drawn into extended lengths of microstructured fiber. New methods of increasing both the structural complexity of fibers and number of materials compatible with the drawing process are substantially expanding the functionality of photonic crystal and semiconductor device fibers (1-3). The drawing process, however, has until now been limited to materials that flow at the draw temperature. Approaches that attempt to circumvent this limitation include depositing materials inside (4-7) or onto the surface (8-11) of previously drawn fiber substrates. These methods do not take full advantage of the scaling associated with fiber drawing and are limited in their geometric complexity and the length over which uniform structures can be produced. Here this seemingly fundamental limitation is lifted by utilizing the fiber drawing process to synthesize in situ a chemical compound that has a melting temperature far exceeding the draw temperature. In this process, precursors are arranged in adjacent domains in a macroscopic preform. During thermal drawing, the fluid reactants come into contact and precipitate a new compound. To demonstrate the potential of this fiber draw synthesis method, a polymer fiber preform containing a thin seleniumsulfur layer next to eutectic tin-zinc wires is constructed and thermally codrawn into a fiber consisting of electrically contacted crystalline ZnSe domains of sub-100-nm scales at the interface between the metallic domains and selenium layer. The formation of the interface compound is the basis for an electronic heterostructure and a thermally drawn fiber device exhibiting rectifying behavior. The ability to synthesize materials during the fiber draw process while maintaining precise and arbitrary geometries should lead to substantial advances in the form and function of fibers. Results and DiscussionA fiber preform consisting of metallic Sn 74 P...

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Introduction to Semiconductor Heterojunctions

Cited by 110 publications

References 0 publications

Electron spin relaxation by nuclei in semiconductor quantum dots

Electron spin relaxation by nuclei in semiconductor quantum dots

ZnO nanorod/GaN light-emitting diodes: The origin of yellow and violet emission bands under reverse and forward bias

Fiber draw synthesis

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