nanocomposites and semiconductor nanostructures

... GaAs and InAs are called direct semiconductors, because the valence band maximum and the conduction band minimum are both at the same point Γ 3.5 Band structure near band extrema: k·p-theory In semiconductor ... GaAs, the valence band maximum and the conduction band minimum are at Γ Comparison of band structures All four band structures appear to be very similar to each other and to the band structure of ... eV, and a V11 = 0.163 eV Unlike in silicon, in GaAs the fundamental band gap appears between the valence band maximum at Γ and the conduction band minimum at Γ The conduction band minima at L and...

Ngày tải lên: 11/06/2014, 10:16

... intensity of the D band, and (d) the G band, together with the images generated from the sample graphene sheet after the nm SiO2 top layer deposition: (e) the D band, and (f) the G band Figure 5.3 ... 532nm(2.33eV), and 633nm(1.96eV) Figure 6.7 The frequencies of Raman mode (D band, 2D band, D+G band) of CNWs as a function of excitation energy Figure 6.8 The intensity ratio of D band to G band ID/IG ... nanotubes and 2D nanographite sheets In the electronic band structure of graphene, the conduction band touches the CHAPTER Introduction valence band at two points (K and K’)5,6 in Brillouin zone, and...

Ngày tải lên: 13/09/2015, 21:36

... four band model of semiconductors (Fedorov et al., 1996) In their model, there are a doubly spin degenerate conduction band, a heavy-hole band, a light-hole band and a spin orbit- split band; and ... the bottom of the conduction band by intraband carrier-carrier and carrier-phonon (optical and acoustical) scattering, and will recombine with holes in the valence band Under high intensity of ... Nanorods and Hetero-junction nanocomposites 1.2.1 Quantum Dots and Nanorods The optical properties of nanocrystals are determined by their electronic structure (Smith and Nie, 2009; Buhro and Colvin,...

Ngày tải lên: 17/09/2015, 17:17

... electronic band structure of GaAs is shown in figure 1.2 From the band structure, the smallest bandgap between the valence band and conduction band occurs at the Γ point making it a direct bandgap semiconductor ... Motivation and objective of the thesis The goal of this thesis is to design and fabricate 3D nanostructures, QDs and QRs on III-V compound semiconductors The fabrication of the 3D nanostructures ... (a) band-to-band transition, (b) free electron-to-acceptor transition, (c) free holeto-donor transition, and (d) donor-acceptor pair transition EV is the valence band, EC is the conduction band,...

Ngày tải lên: 30/09/2015, 06:04

... Conclusion Si and SiOx nanostructures of ®st-capped ®bers, tree-like and tadpole-like objects were generated by heating pure silicon powder at 1373 K under Ar ¯ow SEM, TEM, HRTEM and EDS(X) reveal ... 380 nm diameter) and SiOx nano®bers branches ($3 lm length and 70±230 nm diameter) While, the product in zone C is in the form of tadpoles with di€erent length (Fig 1e) Figs 1f and 1g show that ... that the tadpoles on the left and right side of zone C have lengths of 15±30 and 30±70 lm, respectively At the same time, the ®bers in each `tadpole' coalesced together and formed a bundle (referred...

Ngày tải lên: 16/03/2014, 15:07

... gas handling system and the reactor chamber [15] The gas handling system includes the alkyl and hydride sources and the valves, pumps, and other instruments necessary to control the gas flows and ... of semiconductor nanostructures has been in the area of optoelectronic devices, with the two most important areas being semiconductor lasers and detectors Early efforts focused on band-to-band ... semiconductor nanostructure growth and materials development and also reviews progress in semiconductor devices using nanostructures, with a particular emphasis on 3D nanostructures that have emerged...

Ngày tải lên: 17/03/2014, 13:40

... between the conduction band and the hybridized valence band VBi is 2.2 eV, which is the direct band gap; and the band gap between the conduction band and the oxide valence band VBj is 3.1 to 3.5 eV, ... Energy Bands of Semiconductors The energy bands of frontier electrons in semiconductors consist of a valence band (VB) fiilly occupied by electrons at low energy levels and a vacant conduction band ... distribution and electron-hole pair formation in the conduction and valence bands of intrinsic semiconductors: «F = Fermi level of intrinsic semiconductors 2.4.2 n-type and p-type semiconductors...

Ngày tải lên: 01/04/2014, 11:36

... properties and of the glass transition temperatures of the (A)n and (B)n homopolymers and of the (AB)n random and alternated copolymers and (BAB)n alternated copolymers has been achieved and showed ... led to an increased viscosity and difficulty in handling and degassing materials, producing remnant voids Nonetheless, Jang and other groups such as that of Sohn and Hu [28] showed that the use ... scattering (SAXD) studies of epoxy layered silicate nanocomposites and their in-situ formation have been reported Chin et al [45] and Tolle and Anderson [46] have reported insitu SAXD studies on...

Ngày tải lên: 02/04/2014, 16:28

... measured from the center of the band gap Eg0 , and m˙ and t m˙ represent the contributions to the transverse and longitudinal effective masses l ! of the external LC and L bands arising from the k :! ... spectrum of III–V semiconductors can be described by the three- and two-band models of Kane [103, 104], together with the models of Stillman et al [105], Newson and Kurobe [106], and Palik et al ... types of band models as discussed for III–V semiconductors are also applicable for ternary and quaternary compounds In Sect 1.2.2, the FNFE from QWs of III–V, ternary, and quaternary semiconductors...

Ngày tải lên: 29/05/2014, 16:25

... Ag, and Co), semiconductors (II-VI, III-V, and IV materials), insulators (TiO2, SiO2, mica, and polymers), and magnetic materials (Fe2O3) These colloid particles are pure, stable, uniform, and ... knowledge and personal experience accumulated throughout 18 years of work in the field of physics and technology of thin organic films, organic-inorganic nanostructures, and chemical and biosensing ... colleagues and friends from the Institute of Semiconductor Physics, Academy of Sciences of the Ukraine (Kiev), Sheffield Hallam and Sheffield Universities (United Kingdom), and the other universities and...

Ngày tải lên: 01/06/2014, 10:43

... relation is useful for semiconductor homostructures [7, 8], semiconductor semiconductor heterostructures [9, 10], metals semiconductor heterostructures [11–19] and insulator semiconductor heterostructures ... expressions for n0 and DMR for semiconductors whose energy band structures are 14 The Einstein Relation in Bulk Specimens of Compound Semiconductors defined by the two-band model of Kane and that of ... the three-band model of Kane using the energy band constants as Eg = 0.095 eV, m∗ = m∗ + m∗ / ⊥ || and ∆ = ∆|| + ∆⊥ / The curves (d) and (e) correspond to the two-band model of Kane and that of...

Ngày tải lên: 04/06/2014, 14:44

... ‘‘Ab-initio Methods: DFT and MBPT’’, it is well known that the DFT-LDA severely underestimates the band gaps for semiconductors and insulators A correction to the fundamental band gap is usually obtained ... type II band offset, when there is a planar interface between the two semiconductors This type of offset implies that the minimum of conduction band (CBM) and the maximum of the valence band (VBM) ... electronic and optical properties of Si and Ge nanostructures We have concentrated our interest to those nanostructures that play a role in PV applications In particular, we presented oneparticle and...

Ngày tải lên: 21/06/2014, 17:20

... reveal the existence and hierarchy of sites for enhanced nucleation of new nanostructures In particular 1.4, 1.5 and 1.6 ML of InAs were deposited at 0.01 ML/s, Ts = 510 °C and BEP(As4) = 10-7 ... morphology and differences in the nucleation of InAs nanostructures at the top surface First, as above commented, we observe mounds with the same density as that of the buried nanostructures and with ... between the mounds and the buried nanostructures The results obtained also permit a direct observation of the different preferential sites for nanostructures formation driven by strain and/ or curvature...

Ngày tải lên: 22/06/2014, 00:20

... elongational flow [47] The reflections at 2h = 11 and 21° are -201/200/001 and 020 of the c form, respectively, and the reflections at 2h = *20 and 23° are 200 and 002 of the a form, respectively [47] ... 4:39–46 Materials and Methods Materials e-Caprolactam (99% purity) and 6-aminocaproic acid (6-amino hexanoic acid) (99% purity) were purchased from Aldrich and Sigma, respectively, and used as received ... p-Amino benzoic acid, P-MWNTs, and PPA were placed in resin flask equipped with a mechanical stirrer, and nitrogen inlet and outlet The mixture was heated to 130 °C for h, and P2O5 was then added into...

Ngày tải lên: 22/06/2014, 01:20

... random directions and thus give rise to dendrites or island type morphology of the film structure as shown in the set of micrographs in Fig The exact nature of morphology like dendrites or island, ... radians) and h is of course the Bragg angle The CuKa line has the ˚ average wavelength of 1.54178 A and consists of two lines ˚ CuKa1 and CuKa2 with CuKa1 at 1.5405 A with a shoulder ˚ band of ... mounted on a spinner and the sol was placed on top of it and the wafer was allowed to spin at the rate of 3000 rpm This step was followed by drying the coated wafer at 100 °C and subsequent baking...

Ngày tải lên: 22/06/2014, 18:20

... gas handling system and the reactor chamber [15] The gas handling system includes the alkyl and hydride sources and the valves, pumps, and other instruments necessary to control the gas flows and ... of semiconductor nanostructures has been in the area of optoelectronic devices, with the two most important areas being semiconductor lasers and detectors Early efforts focused on band-to-band ... semiconductor nanostructure growth and materials development and also reviews progress in semiconductor devices using nanostructures, with a particular emphasis on 3D nanostructures that have emerged...

Ngày tải lên: 27/06/2014, 10:20

... in semiconductor nanostructures, and especially for all experiments which are considered in this book, only the Γ6 conduction band and the Γ8 , and – in InGaAs material – the Γ7 valence bands ... index of the Q2D subbands 18 Fundamentals of Semiconductors and Nanostructures Later in this book we will find that, when realized in semiconductor nanostructures, Q2D, Q1D, and Q0D systems are ... Heitmann, and C Sch¨ ller: Phys u Rev B 67, 121309(R) (2003) Fundamentals of Semiconductors and Nanostructures The majority of experiments of inelastic light scattering on semiconductor nanostructures...

Ngày tải lên: 29/06/2014, 09:20

... of NR and ENR nanocomposites Comparing the NR nanocomposites and ENR nanocomposites, the minimum torque and maximum torque of ENR nanocomposites showed higher values than those of the NR nanocomposites ... NR and nanocomposites ENR Figures and show the effect of organoclay loading on stress at 100% elongation (M100) and stress at 300% elongation (M300) of NR and ENR nanocomposites For both NR and ... min–1 RESULTS AND DISCUSSION 3.1 Cure Characteristics Figures and and Table show the results for the scorch time, t2, and cure time, t90, for both organoclay-filled NR nanocomposites and organoclayfilled...

Ngày tải lên: 07/08/2014, 14:20

... excitation and photon emission in semiconductors Figure 1-4: Illustration and comparison of absorption (dashed line) and emission (solid line) spectra, and stokes shift of (a) organic dye and ... Illustration of band structure of inorganic semiconductor as bulk material, nanocrystal and atom (b) Schematic depiction of band diagram of QDs and corresponding electron transition between CB and VB upon ... band (VB) and conduction band (CB) contributed by the ensemble electrons eventually split and show discrete energy states In the meantime, the bandgap, the energy difference between valence band...

Ngày tải lên: 10/09/2015, 09:30

... optoelectronics, memory and sensors.20-22 Introduction and Motivation 1.3 Challenges and Opportunities in Syntheses of Si and Ge Nanostructures Despite the fact that Si and Ge nanostructures are gaining ... Chapter Introduction and Motivation 1.1 Nanotechnology 1.2 Semiconductor Nanostructures 1.3 Challenges and Opportunities in Syntheses of Si and Ge Nanostructures 1.4 ... exploration of self-assembled synthesis and the possible applications of new Si and/ or Ge nanostructures and, (b) achieving a controlled growth of Si and Ge nanostructures 1.4 Organization of Thesis...

Ngày tải lên: 11/09/2015, 10:04