Sn-doped Material Research Articles

D. C. Electrical Conductivity of Ga doped ZnO

Doped ZnO is seen as a potential substitute to the expensive Sn doped material, as a transparent electrode in optoelectronic devices. Here, highly conductive and transparent Ga doped ZnO were prepared by chemical vapor deposition. The lowest resistivity and highest carrier concentration ever reported for CVD grown ZnO, Ga was achieved due to using oxygen poor growth conditions enabled by diethylzinc and triethylgallium precursors. Physical properties like Electrical Conductivity of Zinc Oxide (ZnO) are studied with different doping in it. The dopant to study the varying physical properties of the ZnO semiconductor with respect to Gallium (Ga) semiconductor with changing doping by weight percent of0, 1, 3 and 5 wt. % gallium doped ZnO system are reported here. The electrical properties include dc electrical studies.

Investigation on the structure and electrochemical performance of LiNi0.8Co0.1Mn0.1O2 modified with Sn

Ni-rich layered cathode materials are promising cathode materials for lithium-ion batteries with high energy density. To reveal the influence of Sn-coating and doping on the structure and electrochemical performances of Ni-rich layered cathode materials, LiNi0.8Co0.1Mn0.1O2, LiNi0.8Co0.1Mn0.1O2@xLi2SnO3 and LiNi0.8−xCo0.1Mn0.1SnxO2 (x = 0.02 and 0.04) are designed and synthesized. The effect of lithium-tin-oxide coating and Sn-doping on the structural and electrochemical behavior of Ni-rich cathode material are compared and investigated. Compared with the bare LiNi0.8Co0.1Mn0.1O2 cathode material, both LiNi0.8Co0.1Mn0.1O2@xLi2SnO3 and Sn-doped LiNi0.8−xCo0.1Mn0.1SnxO2 (x = 0.02 and 0.04) samples exhibit better electrochemical performances. The capacity retention for Li2SnO3-coated and Sn-doped materials after 270 cycles at 0.5C can reach as high as 93.7 and 96.6%, respectively. Besides, improved rate capabilities and thermal stability are also obtained for Li2SnO3-coated and Sn-doped materials. The superior electrochemical performances and enhanced thermal stability of Li2SnO3 coated samples are mainly ascribed to the higher interfacial stability and those of Sn-doped materials may be mainly due to higher structural stability and lower polarization than those of the bare LiNi0.8Co0.1Mn0.1O2 cathode material. These results indicate that the introduction of Sn ions, especially Sn doping, may be an effective strategy to improve the performance of Ni-rich layered cathode materials.

Synthesis, electrochemical investigation and structural analysis of doped Li[Ni0.6Mn0.2Co0.2-xMx]O2 (x = 0, 0.05; M = Al, Fe, Sn) cathode materials

Layered Ni-rich Li[Ni0.6Mn0.2Co0.2-xMx]O2 cathode materials (x = 0, 0.05; M = Al, Fe, Sn) are synthesized via a co-precipitation synthesis route and the effect of dopants on the structure and electrochemical performance is investigated. All synthesized materials show a well-defined layered structure of the hexagonal α-NaFeO2 phase investigated by X-ray diffraction (XRD). Undoped LiNi0.6Mn0.2Co0.2O2 exhibits a discharge capacity of 170 mAh g−1 in Li-metal 2032 coin-type cells. Doped materials reach lower capacities between 145 mAh g−1 for Al and 160 mAh g−1 for Sn. However, all doped materials prolong the cycle life by up to 20%. Changes of the lattice parameter before and after delithiation yield information about structural stability. A smaller repulsion of the transition metal layer during delithiation in the Sn-doped material leads to a smaller expansion of the unit cell, which results in enhanced structural stability of the material. The improved structural stability of Sn-doped NMC cathode active material is proven by thermal investigations with the help of Differential Scanning Calorimetry (DSC) and Thermogravimetric Analysis (TGA).

Resonant Levels, Vacancies, and Doping in Bi2Te3, Bi2Te2Se, and Bi2Se3 Tetradymites

The electronic structure of the tetradymites, Bi $$_2$$ Te $$_3$$ , Bi $$_2$$ Te $$_2$$ Se, and Bi $$_2$$ Se $$_3$$ , containing various dopants and vacancies, has been studied using first-principles calculations. We focus on the possibility of formation of resonant levels (RL), confirming the formation of RL by Sn in Bi $$_2$$ Te $$_3$$ and predicting similar behavior of Sn in Bi $$_2$$ Te $$_2$$ Se and Bi $$_2$$ Se $$_3$$ . Vacancies, which are likely present on chalcogen atom sites in real samples of Bi $$_2$$ Te $$_2$$ Se and Bi $$_2$$ Se $$_3$$ , are also studied and their charged donor and resonant behavior discussed. Doping of vacancy-containing materials with regular acceptors, such as Ca or Mg, is shown to compensate the donor effect of vacancies, and $$n-p$$ crossover, while increasing the dopant concentration, is observed. We verify that the RL on Sn is not disturbed by chalcogen vacancies in Bi $$_2$$ Te $$_2$$ Se or Bi $$_2$$ Se $$_3$$ , and for the Sn-doped materials with Se or Te vacancies, double doping, instead of heavy doping with Sn, is suggested as an effective way of obtaining the resonant level. This should help to avoid smearing of the RL, a possible reason for earlier unsuccessful experimental observation of the influence of the RL on the thermoelectric properties of Sn-doped Bi $$_2$$ Te $$_2$$ Se. Finally, we show that Al and Ga are possible new resonant impurities in tetradymites, hoping that this will stimulate further experimental studies.

New Insights into Improving Rate Performance of Lithium-Rich Cathode Material.

A Sn doping strategy is demonstrated to improve lithium diffusion kinetics by expanding the spacing of (003) planes without destroying the layered structure. A large (003) spacing will significantly decrease the energy barrier associated with lithium diffusion. Besides better rate capability, the Sn-doped material exhibits an unexpected much improved capacity above 3.0 V (vs Li(+) /Li), which is highly desired in future applications.

Enhancement in the figure of merit of p-type Bi100−xSbx alloys through multiple valence-band doping

N-type Bi100−xSbx alloys have the highest thermoelectric figure of merit (zT) of all materials below 200 K; here, we investigate how filling multiple valence band pockets at the T and Η-points of the Brillouin zone produces high zT’s in p-type Sn-doped material. This approach, theoretically predicted to potentially give zT > 1 in Bi, was used in PbTe. We report thermopower, electrical and thermal conductivity (2 to 400 K) measurements of single crystals with 12 ≤ x ≤ 37 and polycrystals (x = 50-90), higher Sb concentrations than previous studies. We obtain a 60% improvement in zT to 0.13.

Optical activity of Sn-variants of oxygen deficient centers in fluorine-modified silica

Photoluminescence in fluorine-modified Sn-doped silica has been analyzed by means of synchrotron radiation in the UV and vacuum-UV, from 120 to 330 nm, looking at the optical activity of oxygen-deficient-centers ODC(II) in Sn-substituted cationic sites. The comparison between F-modified Sn-doped samples and previous data on F-free Sn-doped material evidences differences in the intensity of the 3.2 eV emission band excited at 3.7 eV, and in the thermal dependence of the intensity of this emission excited via intersystem crossing. The role of fluorine in modifying the optical activity of ODC(II) and in the SnO 2 clustering is discussed, showing that an efficient excitation transfer may be activated from SnO 2 to the Sn-variant of ODC(II).

High-energy proton radiation induced defects in tin-doped n-type silicon

The formation of radiation defects in Sn-doped Float-Zone (FZ) and Czochralski (Cz) n-type silicon after a high-energy proton irradiation is studied by a combination of Deep Level Transient Spectroscopy (DLTS) and Photoluminescence (PL). Besides the Sn-V levels, evidence is found for at least three new Sn-related radiation defects, two electron traps close to the conduction band and one hole trap close to the valence band. No new PL lines have been identified so far in Sn-doped material. It is furthermore concluded that the Sn-related radiation defects do not show pronounced recombination activity, in the concentration range studied.

Tin Doping of Silicon for Controlling Oxygen Precipitation and Radiation Hardness

This paper reviews the impact of doping silicon with substitutional tin impurities on the formation of intrinsic and extrinsic lattice defects. The two major topics covered are (i) the effect on the diffusivity and aggregation/precipitation of interstitial oxygen in Czochralski (CZ) silicon and (ii) the formation of stable radiation defects in irradiated Sn-doped material. As demonstrated, the compressive stress associated with incorporating a large Sn atom on a lattice site is the basic feature governing the interactions with point defects. Consequently, Sn acts as a selective vacancy trap, while, in contrast, not affecting interstitial reactions. This leads to a reduced formation of oxygen thermal donors in n-type Si and lowers the concentration of vacancy-oxygen and divacancy centers in irradiated material. Enhanced oxygen precipitation has been noted around 750°C in p-type CZ silicon. Furthermore, specific Sn-related radiation defects are introduced, which question the use of doping with tin as a technique for substrate hardening. © 2001 The Electrochemical Society. All rights reserved.

Deep levels in high-energy proton-irradiated tin-doped n-type Czochralski silicon

A deep level transient spectroscopy study of defects created by 61 MeV proton irradiation of tin-doped n-type Czochralski silicon is reported. A comparison is made with the deep levels observed in irradiated p–n junction diodes fabricated in n-type float-zone silicon, without tin doping. The main conclusions are that in Sn-doped material, at least two additional deep radiation centers are introduced at 0.29±0.01 and 0.61±0.02 eV below the conduction band. From annealing experiments, it is concluded that these electron traps dissociate below 120 °C, which is lower than observed before for Sn–V related levels. It is demonstrated that the introduction rates of the well-known radiation defects are significantly smaller in Sn-doped material.

Growth of n- and p-type Al(As)Sb by metalorganic chemical vapor deposition

AlSb and AlAsxSb1−x epitaxial films grown by metalorganic chemical vapor deposition were successfully doped p- or n-type using diethylzinc or tetraethyltin, respectively. AlSb films were grown at 500 ° C and 76 Torr using trimethylamine alane and triethylantimony. AlAs0.16Sb0.84 films lattice matched to InAs were grown at 600 ° C and 76 Torr by adding arsine. Secondary ion mass spectroscopy showed C and O levels below 2×1018 and 6×1018 cm−3, respectively, for undoped AlSb. Similar levels of O were found in AlAs0.16Sb0.84 films but C levels were an order of magnitude less in undoped and Sn-doped AlAs0.16Sb0.84 films. Hall measurements of AlAs0.16Sb0.84 showed hole concentrations between 1×1017 to 5×1018 cm−3 for Zn-doped material and electron concentrations in the low to mid- 1018 cm−3 for Sn-doped material.

The Growth and Doping of Al(As)Sb by Metal-Organic Chemical Vapor Deposition

AbstractAlSb and AlAsxSb1−x epitaxial films grown by metal-organic chemical vapor deposition were successfully doped p- or n-type using diethylzinc or tetraethyltin, respectively. AlSb films were grown at 500°C and 76 torr using trimethylamine or ethyldimethylamine alane and triethylantimony. We examined the growth of AlAsSb using temperatures of 500 to 600 ° C, pressures of 65 to 630 torr, V/Ill ratios of 1–17, and growth rates of 0.3 to 2.7 μm/hour in a horizontal quartz reactor. SIMS showed C and 0 levels below 2 × 1018 cm−3 and 6×1018 cm−3 respectively for undoped AlSb. Similar levels of O were found in AlAs0.16Sb0.84 films but C levels were an order of magnitude less in undoped and Sn-doped AlAs0.16 Sb0.84 films. Hall measurements of AlAs0.16Sb0.84 showed hole concentrations between l×1017 cm−3 to 5×1018 cm−3 for Zn-doped material and electron concentrations in the low to mid 1018 cm−3 for Sndoped material. We have grown pseudomorphic InAs/InAsSb quantum well active regions on AlAsSb cladding layers. Photoluminescence of these layers has been observed up to 300 K.

The effect of defects on some photoelectrochemical properties of semiconducting MgFe 2O 4

Undoped Magnesium Ferrite, when functioning as a photoanode in aqueous solution, shows a large transient current response; in contrast Sn-doped material shows no transients and has comparatively small photocurrents. This difference is correlated with the resistivities of the samples and is attributed to the presence of defects in the undoped material. The undoped material shows a photoresponse at 1.1 eV photon energy, well below the 2.18 eV bandgap of MgFe 2O 4. A comparison with the analogous properties of Fe 2O 3 is made.

TEM observation in cross section of defects in a long-term-degraded Ga1−xAlxAs double-heterostructure injection laser diode

A degraded Ga1−xAlxAs double-heterostructure injection cw laser diode with a lifetime of 1070 h was examined in cross section by TEM. The device contains defects whose contrast is identical to that produced by coherent or partially coherent precipitates and/or by prismatic dislocation loops. They have not previously been observed either in undegraded Ge- or Sn-doped material or in devices degraded by DLD formation. These defects were observed in the top p (Ge) -GaAs layer as well as in the p (Ge) -Ga1−xAlxAs layer adjacent to it. There is a tendency for these defects to decorate the interface between these two layers as well as the interface between the active region and the p (Ge) -Ga1−xAlxAs layer. Furthermore, these defects seem to cluster in regions adjacent and above these two interfaces. These defects have not, however, been observed in the active, the n- (Sn) -Ga1−xAlxAs, and the n-GaAs substrate regions.