69,832 research outputs found
Native p-type transparent conductive CuI via intrinsic defects
No full textThe ability of CuI to be doped p-type via the introduction of native defects has been investigated using first-principles pseudopotential calculations based on density functional theory. The Cu vacancy has a lower formation energy than any of the other native defects, which include I vacancy (V(I)), Cu interstitial (Cu(i)), I interstitial (I(i)), Cu antisite (Cu(I)), and I antisite (I(Cu)). Combined with its shallow acceptor level, it offers sufficient hole concentrations in CuI. The natural band alignments as compared to zinc-blende ZnS, ZnSe, and ZnTe have also been calculated in order to further identify the p-type dopability of CuI. It is found that CuI has a relatively high valence band maximum and conduction band minimum, which also makes it easy to dope CuI p-type in terms of the doping limit rule. In addition, the small effective mass of the light hole-about 0.303m(0)-can provide high mobility and p-type conductivity in CuI. All of these results make CuI an ideal candidate for native p-type materials (C) 2011 American Institute of Physics. [doi:10.1063/1.3633220
Growth Strategy and Physical Properties of the High Mobility P-Type CuI Crystal
No full textAcquiring stable binary wide band-gap semiconductor (WBS) materials with high p-type mobility is essential for the development of WBS optoelectronic devices. CuI is-a p-type WBS material with a large band gap (3.1 eV) and high exciton binding energy (62 meV). However, the semiconductor-characteristics of the CuI single crystal are unknown due to the lack of a large sized and high quality crystal. Our approach focuses on the design of the mineralizer for the hydrothermal method to effectively control the growth habit and the impurity concentration in the crystal. A large size (15 mm x 10 mm x 1 mm) and high quality CuI single crystal is obtained by using a new mineralizer (NH4I + KI). The crystal shows high p-type mobility (43.9 cm(2).V-1.S1-). The strong and sharp band-edge emission at 410 nm indicates that the interband excitonic transition dominates the optical response in the spectrum. Such a binary crystalline material may open the way to new applications in optoelectronic devices
CuI-functionalized halloysite nanoclay as an efficient heterogeneous catalyst for promoting click reactions: Combination of experimental and computational chemistry
No full text Amine-functionalized
halloysite nanotubes (HNTs-2 N) were prepared and further modified by introduction of salicylaldehyde
and formation of imine functionality (HNTs-2 N-Sal). The latter was
subsequently used for immobilization of CuI and formation of
CuI@HNTs-2 N-Sal, which could effectively promote click reactions of
terminal alkynes, sodium azide and α-haloketones or alkyl halides in aqueous
media and under mild reaction conditions to afford 1,2,3-triazoles in
relatively short reaction times. Notably, the catalyst could be recycled in up
to six reaction runs with negligible loss of catalytic activity and CuI
leaching. Also, the geometry of CuI adsorption on the modified HNTs surface was
explored by molecular simulation with density functional theory. Furthermore,
topographic steric maps of possible coordination modes were obtained using the
recently released SambVca2 web application tool. Based on obtained results, a
catalytic site with superior performance was suggested.</p
CuI as a P-type Transparent Semiconductor
No full textWe propose a simple new method for the synthesis of truly transparent p-type CuI films. The chemical reaction between Cu3N thin films and solid-phase iodine was found to yield highly transparent polycrystalline CuI films with shiny appearance. An as-prepared film had a resistivity of 1.1x10-1Ω cm, hole density (nh) of 1.1x1019cm-3, and mobility (μ) of 5.6cm2 V-1s-1. Mild heat treatment at 100-120℃ under an inert atmosphere was found to suppress nh and enhance μ. The heat-treated films had μvalues of 20cm2V-1s-1, which are much higher than those of other wide-bandgap p-type semiconductors grown epitaxially at high temperatures above 400℃. Furthermore, we successfully fabricated p-CuI/i-ZnO/n-ZnO heterojunctions with good rectification ratios exceeding 104 on PET substrates. These findings would assist studies on applications of CuI thin films in transparent electronics
-type CuI
No full textArt. 051101, 9 S.For every semiconducting material, the long-term stability of thin film characteristics is a crucial necessity for device applications. This is particularly true for the p-type semiconductor CuI, where the thin film properties are especially sensitive to environmental influences and motivate the application of capping materials. Utilizing pulsed laser deposition (PLD) and Al2O3 cappings, we performed systematic studies on the N2/O2 partial pressure during growth and the effect of layer thickness. Our results suggest that oxygen, acting as an acceptor, and its diffusion through Al2O3 and CuI dominate the conductivity of PLD grown CuI thin films. The diffusion process of atmospheric oxygen into CuI was traced with 18O-isotopes. Additionally, the transparency and morphology of CuI films are also affected by the oxygen supply during capping growth. These results challenge the currently accepted idea that intrinsic, and not extrinsic, effects determine the conductivity of CuI thin films.9Nr.
Robustagramma triangulatum Cui and Marshall 2005
No full text<i>Robustagramma triangulatum</i> group <p> Diagnosis: Dorsocentral bristles in three pairs. Prosternum narrow, bare. Wing pigmented, with two transverse, zigzag, clear bands beyond end of R 2+3; R 2+3 short and straight. Distiphallus with nodes on paired whip­like sclerites.</p>Published as part of <i>Marshall, Stephen A. & Cui, Yongsheng, 2005, Systematics of Robustagramma, a new genus of New World Sphaeroceridae (Diptera), pp. 1-122 in Zootaxa 1026 (1)</i> on page 92, DOI: 10.11646/zootaxa.1026.1.1, <a href="http://zenodo.org/record/5049813">http://zenodo.org/record/5049813</a>
Improving the robustness of location-based routing for underwater sensor networks
No full textThis paper investigates a fundamental networking problem in underwater sensor networks: robust and energy-efficient routing. We present an adaptive location-based routing protocol, called hop-by-hop vector-based forwarding (HH-VBF). It uses the notion of a "routing vector" (a vector from the source to the sink) acting as the axis of the "routing pipe", similar to the vector based forward (VBF) routing in the work of P. Xie, J.-H. Cui and L. Lao (VBF: Vector-Based Forwarding Protocol for Underwater Sensor Networks. Technical report, UCONN CSE Technical Report: UbiNet-TR05-03 (BECAT/CSE-TR-05-6), Feb. 2005). Unlike the original VBF approach, however, HH-VBF suggests the use of a routing vector for each individual forwarder in the network, instead of a single network-wide source-to-sink routing vector. By the creation of the hop-by-hop vectors, HH-VBF can overcome two major problems in VBF: (1) too small data delivery ratio for sparse networks; (2) too sensitive to "routing pipe" radius threshold. We conduct simulations to evaluate HH-VBF, and the results show that HH-VBF yields much better performance than VBF in sparse networks. In addition, HH-VBF is less sensitive to the routing pipe radius threshold. Furthermore, we also analyze the behavior of HH-VBF and show that assuming proper redundancy and feedback techniques, HH-VBF can facilitate the avoidance of any "void" areas in the network
(CuI)₃P₄S₄: Preparation, structural, and NMR spectroscopic characterization of a copper(I) halide adduct with β-P₄S₄
No full text(CuI)(3)P4S4 is obtained by reaction of stoichiometric amounts of CuI, P, and S in evacuated silica ampoules. The yellow compound consists of monomeric beta-P4S4 cage molecules that are separated by hexagonal columns of CuI. (CuI)(3)P4S4 crystallizes isotypic to (CuI)(3)P4Se4 in the hexagonal system, space group P6(3)cm (no. 185) with a = 19.082(3), c = 6.691 (1) Angstrom, V = 2109.9(6) Angstrom(3), and Z=6. Three of the four phosphorus atoms are bonded to copper, whereas no bonds between copper and sulfur are observed. The two crystallographically distinct copper sites are clearly differentiated by Cu-65 magic-angle spinning (MAS) NMR spectroscopy. Furthermore, an unequivocal assignment of the P-31 MAS-NMR spectra is possible on the basis of homo- and heteronuclear dipole-dipole and scalar interactions. Dipolar coupling to the adjacent quadrupolar spins Cu-63 65 generates a clear multiplet structure of the peaks attributable to P1 and P2, respectively. Furthermore, the utility of a newly developed two-dimensional NMR technique is illustrated to reveal direct connectivity between P atoms based on (P-31-P-31) scalar interactions
Robustagramma gigantisclerosum Marshall & Cui 2005
No full textgigantisclerosum Marshall & Cui, 2005. Type locality: Ecuador, (Pichincha), Río Palenque. HT M (DEBU). Distr.: Colombia (Norte de Santander (Santiago, 2,000 ft), Belize, Bolivia, Costa Rica, Ecuador, Guatemala, Guyana, Mexico, Panama, Peru, Trinidad, Venezuela. Refs: Marshall & Cui, 2005: 72 (key, diag.); Marshall et al., 2011: 273 –274 (cat.).Published as part of Tepedino, Karla P., 2016, FAMILY SPHAEROCERIDAE, pp. 685-695 in Zootaxa 4122 (1) on page 691, DOI: 10.11646/zootaxa.4122.1.59, http://zenodo.org/record/26473
Robustagramma spinatimargo Marshall & Cui 2005
No full textspinatimargo Marshall & Cui, 2005: 88. Type locality: Venezuela, Aragua, Maracay, Rancho Grande, (1,200 m). HT M (IZAV). Distr.: Colombia (Norte de Santander (Santiago, 2.000 ft)), Venezuela. Refs.: Marshall & Cui, 2005: 88 (key, diag.); Marshall et al., 2011: 276 (cat.).Published as part of Tepedino, Karla P., 2016, FAMILY SPHAEROCERIDAE, pp. 685-695 in Zootaxa 4122 (1) on page 691, DOI: 10.11646/zootaxa.4122.1.59, http://zenodo.org/record/26473
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