Oxyphosphide Research Articles

Synthesis, crystal structure and superconductivity of LaNiPO

Single crystals of LaNiPO were synthesized by reacting La, P and NiO at 1173 K in a tin flux under argon atmosphere. A phase analysis and crystal structure determination was carried out using X-ray powder and single crystal methods. The quaternary phosphide oxide crystallizes in the tetragonal ZrCuSiAs structure ( P4/ nmm, a = 404.53(1) pm, c = 810.54(3) pm, Z = 2), which is characterized by layers of edge-sharing [La 4/4 O] ∞ 2 and [NiP 4/4 ] ∞ 2 tetrahedra alternating along [001]. LaNiPO is a Pauli paramagnetic metal at room temperature and becomes a type-II superconductor at T C = 4.3 K with an upper critical field H c2 ≈ 320 mT at 1.8 K. Connections between the crystal chemistry and the occurrence of superconductivity in LaNiPO and related ThCr 2Si 2 type compounds are discussed.

Dimorphic CeZnPO and PrZnPO

AbstractWell‐shaped single crystals of the phosphide oxides CeZnPO and PrZnPO were obtained from the rare earth metals, zinc oxide, and red phosphorous in an equimolar NaCl/KCl flux in sealed quartz ampoules. The high‐temperature (β) NdZnPO type modifications were obtained at 1170 K while the low‐temperature (α) ZrCuSiAs type modifications crystallized at 970 K. The four compounds were characterized by X‐ray diffraction on powders and single crystals: P4/nmm, a = 401.08(9), c = 882.0(4) pm, wR2 = 0.1277, 173 F2 values, 9 variables for α–CeZnPO, a = 399.3(2), c = 877.2(7) pm, wR2 = 0.0583, 220 F2 values, 12 variables for α–PrZnPO, and R3m, a = 401.2(4), c = 3121(3) pm, wR2 = 0.0221, 509 F2 values, 14 variables for β–CeZnPO, a = 399.0(2), c = 3108(1) pm, wR2 = 0.0452, 291 F2 values, 14 variables for β–PrZnPO. In both modifications we observe clear separation into rare earth–oxygen and zinc–phosphorous layers without any P–P and Zn–O interactions, leading to electron precise formulations Ce3+Zn2+P3−O2− and Pr3+Zn2+P3−O2− for these transparent compounds. The crystal chemical peculiarities are briefly discussed.

Oxidation of vanadium films on InP substrates

The kinetics and mechanism of the thermal oxidation of V/InP structures in flowing oxygen are investigated by x-ray diffraction and IR spectroscopy. The results demonstrate that the oxidation of thin (25 nm) vanadium films yields various oxides, which accelerate the oxidation of indium phosphide, leading to the formation of multiphase dielectric layers through a number of parallel reactions.

Quaternary Phosphide Oxides Pr3Cu4P4O2–x and Sm3Cu4P4O2–x with Ordered Zr3Cu4Si6-Type Structure

The compounds Ln3Cu4P4O2-χ (Ln = Pr, Sm) were prepared by annealing the elemental components in a NaCl/KCl flux. They crystallize with an ordered Zr3Cu4Si6-type structure (space group I4/mmm, Z = 2), which was refined from single-crystal X-ray data for both compounds; Pr3Cu4P4O2-χ: a = 397.8(1), c = 2658.7(3) pm, R = 0.046 for 235 structure factors and 19 variable parameters; Sm3Cu4P4O2-χ: a = 392.8(1), c = 2643.6(3) pm, R = 0.057 for 145 F values and 19 variables. The refinements showed partial occupancy for the oxygen positions resulting in approximately 1.5 oxygen atoms per formula unit. Half of the phosphorus atoms form pairs with typical two-electron bond distances of 222.8(4) and 221.7(8) pm, respectively. Using oxidation numbers chemical bonding in these phosphide oxides can be rationalized with the formula (Ln+3)3(Cu+1)4(P-P)-4(P-3)2(O-2)1.5. Hence, the empirical formula may also be doubled (Ln6Cu8P8O3), and the compounds are expected to be semiconducting.

Vibrational study of indium phosphide oxides

Passivation of semi-insulating indium phosphide surfaces by various types of oxides is investigated with infrared absorption spectroscopy (IRAS) and X-ray photoelectron spectroscopy (XPS). The difficulty in studying oxide-related modes in the 800–1300 cm −1 range is due to the bulk phonon absorption of the InP substrate and has stimulated the optimization of single-pass “external” transmission as well as multiple internal reflection geometries for ex situ and in situ studies, respectively. The nature of oxides prepared commercially for epitaxy (epi-ready) and oxides prepared by wet chemistry is studied as well as the wet chemical etching of such oxides, including the reactivity of InP in various solutions. Combining XPS and polarization-dependent IRAS, we find that epi-ready oxides tend to be porous, and plasma-grown oxides denser.

Solid-State Reactions Underlying the Thermal Oxidation of Ni/InP Structures

The layers grown by thermal oxidation of indium phosphide coated with vacuum-deposited nickel were characterized by ellipsometry, IR spectroscopy, x-ray energy spectroscopy, x-ray diffraction, and electrical measurements. The results demonstrate that the layers consist mainly of indium phosphates and nickel phosphates and polyphosphates. The Ni layer acts as a barrier which prevents phosphorus diffusion to the surface and ensures the growth of phosphates and polyphosphates in the surface layer. A model for the thermal oxidation of Ni/InP structures is proposed.

Effect of VO+2 Cation on the Nitric Acid Oxidation of Indium Phosphide

The nitric acid oxidation of indium phosphide was found to be notably accelerated by VO+2. The reaction scheme of the process was proposed. The composition of the forming oxide layers was determined by IR and x-ray energy spectroscopy techniques.

Thermal oxidation of indium phosphide in the presence of lead, zirconium, and titanium oxides

A nonlinear effect of activation of InP thermal oxidation by lead, titanium, and zirconium oxides introduced during the process was discovered. The source of the activating admixtures was their solid solution. Under such conditions, mass transfer of metal cations towards the outer interface of the solid-phase source becomes the reaction-rate-limiting process. Oxide formation in an InP film is the governing process

Equiatomic Quaternary Rare Earth Element Zinc Pnictide Oxides RZnPO and RZnAsO.

The twelve phosphide oxides RZnPO (R = Y, La-Nd, Sm, Gd-Tm) and the nine arsenide oxides (R = Y, La-Nd, Sm, Gd-Dy) have been prepared by reaction of the rare earth elements, ZnO, and phosphorus or arsenic, respectively, in a NaCl/KCl flux. The compounds RZnPO (R = Y, Pr, Nd, Sm, Gd-Tm) crystallize with a new trigonal rhombohedral structure type, determined from single-crystal X-ray diffractometer data of NdZnPO: R&thremacr;m, a = 397.7(1) pm, c = 3097.5(5) pm, Z = 6. The other eleven compounds are isotypic with ZrCuSiAs (P4/nmm, Z = 2). This tetragonal structure was refined from single-crystal X-ray data of LaZnPO (a = 404.0(1) pm, c = 890.8(2) pm) and NdZnAsO (a = 403.0(1) pm, c = 894.9(4) pm). In both structure types rare earth element-oxygen layers alternate with zinc-pnictogen layers. The rare earth element atoms have four oxygen and three (NdZnPO) or four (LaZnPO, NdZnAsO) pnictogen neighbors. The zinc atoms have tetrahedral pnictogen coordination. The arsenide oxides as well as the tetragonal phosphide oxides LaZnPO and CeZnPO are black, while the other (trigonal) phosphide oxides are transparent. The more metallic character of the tetragonal compounds is ascribed to their more delocalized chemical bonding, as is indicated by their higher coordination numbers, which in part also result through significant Zn-Zn bonding.

The rate earth transition metal phosphide oxides LnFePO, LnRuPO and LnCoPO with ZrCuSiAs type structure

The compounds LnFePO (Ln = La−Nd, Sm, Gd), LnRuPO (Ln = La−Nd, Sm, Gd) and (Ln = La−Nd, Sm) crystallize with the tetragonal) ZrCuSiAs type structure ( P4/ nmm, Z = 2), which was refined from single-crystal X-ray data of PrFePO ( a = 391.13(6) pm, c = 834.5(2) pm, R = 0.026) and CeRuPo ( a = 402.6(1) pm, c = 825.6(2) pm, R = 0.018). The refinement of the occupancy parameters showed the oxygen position to be fully occupied in both compounds. The oxygen content of the samples was also proven by EDAX analyses. The structures of the compounds SmFePO and LaCoPO were refined by Rietveld analyses of X-ray powder data.

In Situ Studies of the Anodic Oxidation of Indium Phosphide

The anodic oxidation of indium phosphide has been investigated using ellipsometric measurements. The in situmeasurements revealed a two‐layer system: an outer indium‐rich oxide layer and, close to the substrate, a phosphorus‐rich oxide layer. This two‐layer composition was obtained with different electrolytes: a complex glycol‐based solution and pure water. Considering these experimental results, a tentative explanation for the oxidation mechanism is proposed. The oxide growth is controlled by the drift of ionic species under the electric field. The anodic efficiency, which is defined as the ratio of ionic charge to total charge, is dependent on the barrier height at the electrolyte/oxide interface. Therefore the reduction of the growth rate as the oxidation proceeds is explained by the change in the surface composition.

Oxidation of GaP in an Aqueous H 2 O 2 Solution

The oxidation of gallium phosphide in aqueous has been accomplished by both galvanic action at about 106°C and by externally applied anodic reaction at room temperature. These oxides can be used as passivation materials in light‐emitting devices. A detailed examination of the kinetics of galvanic oxide growth indicates that the oxidation mechanism involves predominantly the transfer of holes, and the rate‐controlled step in the growth mechanism involves the diffusion of the oxidant through the growth oxide. The growth of an oxide by externally applied anodic bias has resulted in the fact that the oxide thickness depends linearly on the applied bias up to about 150V, with the proportionality constant being 13 Å/V. Uniform films can be obtained with up to 200V of forming voltage. In order to obtain a stable amorphous oxide, a drying procedure to remove the water of hydration is necessary for both methods.

Indium phosphide oxide on Inp for MOSFET applications

Oxide films have been deposited on InP by sputtering InP in an oxygen DC-excited plasma. The rate of sputtering was enhanced by applying a magnetic field. Preliminary microprobe and Auger analysis of the films has indicated equal proportions of indium and phosphorus with a good incorporation of oxygen and a moderately uniform composition. Measurements on MOS devices have shown a film resistivity of ̃3 × 1012 σcm. The oxide film has been used in fabricating n-channel inversion-type MOSFETs.

Local atomic order in native III–V oxides

This paper considers the nature of the local atomic boning in native III–V oxides. On the basis of comparisons with the elemental oxides of the constituent group V atoms, we argue that the key factor in establishing the increased stability of phosphide oxides relative to both arsenide and antimonide oxides is a donor–acceptor pair bond, P=O, that is well-known in phosphorous–oxygen chemistry. The stability of this bond is to a large extent related to its partial π-bonding character. Detection of this group at oxidized surfaces or in the bulk of anodized oxides, should be possible by Raman scattering or low energy electron loss spectroscopy.

Anodic Oxidation of GaP in N‐methylacetamide for Electrical Profiling of Ion‐Implanted GaP

The anodic oxidation of gallium phosphide in properly pH‐adjusted NMA solutions was carried out under constant current conditions. Uniform oxides have been reproducibly grown in NMA with 10% . The pH was adjusted to 12 using and readjusted to 8.5–10 using citric acid. The oxide thickness‐forming voltage relationship is linear, with a slope of approximately 11 Å · V−1, independent of current density from 0.125–4.0 mA · cm−2. The thickness of consumed during the oxide growth voltage relationship is also linear, but its slope varies with current density (, mA · cm−2) and is described empirically as . Electrical carrier‐concentration and mobility profiles in Zn‐implanted were obtained by differential Hall‐effect and sheet‐resistivity measurements combined with an oxide growth‐stripping process, where anodization is performed under optimumly defined conditions.

ChemInform Abstract: ANODIC OXIDATION AND ELECTRICAL CARRIER CONCENTRATION PROFILES OF ION‐IMPLANTED INDIUM PHOSPHIDE

Chemischer InformationsdienstVolume 10, Issue 15 Physical Inorganic Chemistry ChemInform Abstract: ANODIC OXIDATION AND ELECTRICAL CARRIER CONCENTRATION PROFILES OF ION-IMPLANTED INDIUM PHOSPHIDE J. P. LORENZO, J. P. LORENZOSearch for more papers by this authorD. E. DAVIES, D. E. DAVIESSearch for more papers by this authorT. G. RYAN, T. G. RYANSearch for more papers by this author J. P. LORENZO, J. P. LORENZOSearch for more papers by this authorD. E. DAVIES, D. E. DAVIESSearch for more papers by this authorT. G. RYAN, T. G. RYANSearch for more papers by this author First published: April 10, 1979 https://doi.org/10.1002/chin.197915015Read the full textAboutPDF ToolsRequest permissionExport citationAdd to favoritesTrack citation ShareShare Give accessShare full text accessShare full-text accessPlease review our Terms and Conditions of Use and check box below to share full-text version of article.I have read and accept the Wiley Online Library Terms and Conditions of UseShareable LinkUse the link below to share a full-text version of this article with your friends and colleagues. Learn more.Copy URL Share a linkShare onFacebookTwitterLinkedInRedditWechat No abstract is available for this article. Volume10, Issue15April 10, 1979 RelatedInformation

Anodic oxidation of indium phosphide in glycol-based solutions

An anodic native oxide has been grown onto indium phosphide using glycol-based solutions. The variation of the anodic current behaviour with various circuit parameters has been measured, together with the thickness of the oxide as a function of voltage. MOS capacitor structures have been fabricated using this native oxide as the insulator and the I/ V and C/ V characteristics of these structures have been measured and analysed.