Stoichiometric InSb Research Articles

Investigation of electrodeposition kinetics of In, Sb, and Zn for advanced designing of InSb and ZnSb thin films

In this work, the kinetics of indium, antimony, and zinc electrodepositions were investigated by using a gold rotating disc electrode (RDE). The performed studies shed light on the influence of electrodeposition parameters (i.e., working electrode potential and hydrodynamic conditions) on the chemical composition of In-Sb and Zn-Sb films. Stoichiometric InSb and ZnSb are one of the most promising thermoelectric materials, therefore a strictly controlled chemical composition of deposits is required. During electrochemical studies, as a primary electrolyte, a citrate bath with the addition of metal ion precursors, i.e., 0.06 M InCl 3 and/or 0.045 M SbCl 3 and/or 0.045 M ZnCl 2 , was applied. Based on the linear voltammetry measurements in the RDE system, the Koutecký-Levich analyses were performed. The diffusion coefficients ( D ) determined at 293 K for indium, antimony, and zinc ions equal to 1.45 × 10 −6 , 3.76 × 10 −6 , and 5.94 × 10 −6 cm 2 s −1 , respectively. The activation energy ( E A ) for the diffusion of metal ions was determined using D values calculated at different temperatures. E A of indium, antimony, and zinc ions equals to 25.1, 9.2, and 10.6 kJ mol −1 , respectively. The number of transferred electrons ( n ) and rate constant for heterogeneous reactions ( k ) occurring in the studied electrolytes at different potentials were also determined. • Electrodeposition of In, Sb, and Zn is under diffusion and kinetics control. • Diffusion coefficient of ion increase in line: In-citrate<Sb-citrate<Zn-citrate. • Adsorption of citrate ions on the RDE surface slows down electroreduction of In. • Indium-citrate ions have the highest E A of diffusion among studied species.

Study of InSb thin films grown on different substrates by the pulsed electrodeposition technique

Stoichiometric InSb thin films were prepared, on four different substrates, using a pulsed electrodeposition technique. The electrochemical bath used for the growth of InSb thin films was made up of a mixture of aqueous solutions of indium trichloride (InCl3), antimony trichloride (SbCl3), citric acid (C6H8O7·H2O) and sodium citrate (Na3C6H5O7·2H2O). Energy dispersive analysis of X rays along with X-ray diffraction (XRD) studies show that the elemental composition and crystalinity of thin films is strongly dependent on the ionic composition of the electrochemical bath. Stoichiometric InSb thin films can be grown on all the four substrates from the same bath, by properly selecting the composition of the bath. XRD studies show that the InSb thin films grown on all the four substrates have preferred orientation along the (111) plane. The presence of sharp Raman peaks of longitudinal optical phonon mode and transverse optical phonon mode in stoichiometric thin films confirm that they are of good crystalinity.

Hole-dominated transport in InSb nanowires grown on high-quality InSb films

We have developed an effective strategy for synthesizing p-type indium antimonide (InSb) nanowires on a thin film of InSb grown on glass substrate. The InSb films were grown by a chemical reaction between Sb2S3 and In and were characterized by structural, compositional, and optical studies. Scanning electron microscopy (SEM) and atomic force microscopy (AFM) studies reveal that the surface of the substrate is covered with a polycrystalline InSb film comprised of sub-micron sized InSb islands. Energy dispersive X-ray (EDX) results show that the film is stoichiometric InSb. The optical constants of the InSb film, characterized using a variable-angle spectroscopic ellipsometer (VASE) shows a maximum value for refractive index at 3.7 near 1.8 eV, and the extinction coefficient (k) shows a maximum value 3.3 near 4.1 eV. InSb nanowires were subsequently grown on the InSb film with 20 nm sized Au nanoparticles functioning as the metal catalyst initiating nanowire growth. The InSb nanowires with diameters in the range of 40–60 nm exhibit good crystallinity and were found to be rich in Sb. High concentrations of anions in binary semiconductors are known to introduce acceptor levels within the band gap. This un-intentional doping of the InSb nanowire resulting in hole-dominated transport in the nanowires is demonstrated by the fabrication of a p-channel nanowire field effect transistor. The hole concentration and field effect mobility are estimated to be ≈1.3 × 1017 cm−3 and 1000 cm2 V−1 s−1, respectively, at room temperature, values that are particularly attractive for the technological implications of utilizing p-InSb nanowires in CMOS electronics.

Electrodeposition of Stoichiometric Indium Antimonide from Room‐Temperature Ionic Liquid 1‐Butyl‐1‐Methylpyrrolidinium Dicyanamide

AbstractA stoichiometric InSb film was electrodeposited on a nickel (Ni) substrate in a room‐temperature ionic liquid, 1‐butyl‐1‐methylpyrrolidinium dicyanamide (BMP‐DCA), containing anhydrous InCl3 and SbCl3 with a molar concentration ratio of 1:1. The composition of the deposited InSb film was found to depend on both the applied potential and the deposition charge. Crystalline deposits can be directly obtained at low temperature (60 °C) without any post‐heat treatment. The optical band gap of the InSb film analyzed by using FTIR spectroscopy measurements was approximately 0.17 eV. Results from photocurrent experiments indicate that the electrodeposited InSb film was a p‐type semiconductor.

Electrochemically deposited nanocrystalline InSb thin films and their electrical properties

Indium antimonide thin films were fabricated by pulse electrodeposition. Band gap widening due to quantum confinement (0.17 eV) and the Burstein–Moss effect (0.19 eV) was observed. The stoichiometric InSb films showed S coefficient values higher than those obtained by MOCVD.

Defect formation in InSb nanowires and its effect on stoichiometry and carrier transport

This paper presents a study of point defects that exist as a result of non-stoichiometry in InSb nanowires. Using thermodynamics, equilibrium defect concentrations are estimated as a function of antimony vapor pressure. The point defects under study are indium and antimony mono-vacancies and charged versions of these. The magnitude of the defect concentrations is determined by estimating the equilibrium constant for each of the reaction equations, and their values are in agreement with experimental data. At 526 °C, corresponding to the temperature of formation of stoichiometric InSb crystals, the approximate defect concentration is estimated to be of the order of 1018 cm−3. To validate the defect model, InSb nanowires that were ≈10 μm long and had diameters in the range of 40–80 nm, were synthesized by direct antimonidization of In droplets. The nanowire stoichiometry was studied as a function of growth temperature and antimony partial pressure. Our experimental results show that it was essential to maintain an overpressure of antimony-rich vapor for the growth of stoichiometric InSb nanowires. Transport measurements on a single near-stoichiometric InSb nanowire show an electron concentration of ≈2.7 × 1018 cm−3, while the indium-rich InSb nanowires were found to have a higher electron concentration of ≈4 × 1019 cm−3. Metallic In nanowires grown at 600 °C had an electron concentration of ≈1.4 × 1021 cm−3.

A Study of Point Defects and Cause of Nonstoichiometry in InSb Nanowires

ABSTRACTSynthesis of InSb nanowires using chemical vapor deposition (CVD) is technically challenging due to the tuning of III-V vapor pressures. Growth parameters such as the choice of the metal catalyst, growth temperature and vapor pressure of constituents affect the morphology and stoichiometry of InSb nanowires. By controlling the growth temperature, it was possible to grow either stoichiometric InSb nanowires or In nanowires that contained no Sb within detectable limits. We present a simple model to show that the occurrence of native point defects in InSb is influenced by the growth kinetics and by the thermodynamics of defect formation. Results from this model are in good agreement with our experimental findings of the evidence of point defects in these nanowires.

Influence of growth temperature on the stoichiometry of InSb nanowires grown by vapor phase transport

We report on the influence of growth parameters on the stoichiometry of indium antimonide nanowires grown by vapor phase transport. Using electron microscopy and composition analysis, we show that there is an optimum growth temperature window for growing stoichiometric indium antimonide (InSb) nanowires. The choice of the metal catalyst, evaporation and growth temperature are all critical parameters affecting the morphology and stoichiometry of the growing crystal. By controlling the growth temperature, it was possible to grow either stoichiometric InSb nanowires or In nanowires that contained no Sb within detectable limits. Electrical transport measurements of single InSb nanowires with two ohmic contacts demonstrate n-type conduction persisting from room temperature to 15 K.

III-V족 화합물 반도체 InSb 나노와이어의 전기화학적 합성 및 특성 평가

본 연구에서는 그동안 전기화학적으로 합성되지 못했던 III-V족 화합물 반도체 InSb를 구연산 용액으로부터 합성하였으며 자체 제조한 AAO를 나노템플릿으로 이용하여 정전압 도금을 실시하여 InSb 나노와이어를 제조하였다 제조된 InSb나노와이어는 X선 회절분석 결과 단결정의 나노와이어는 아니었으나 정확하게 화학양론을 만족시키는 화합물임을 확인하였고, 평판 박막 상태의 InSb와는 달리 나노와이어의 길이방향으로 (220) 방향의 결정이 주로 성장하는 우선결정방위를 가지고 있음을 알 수 있었다. 또한 집합적으로 배열된 상태에서 측정된 I-V특성 곡선에서는 n형 반도체의 특성을 보이되 밴드갭이 좁고, 전자이동도가 큰 InSb고유의 특성상 반금속과 유사한 전기적 특성을 보유하고 있음을 확인하였다. To the best knowledge, the formation and characterization of InSb nanowires have not been reported yet in spite of its good characteristics as a III-V compound semiconductor. The nanowire arrays were potentiostatically electrodeposited in a mixing solution of indium chloride, antimony chloride, citric acid, and potassium citrate according to our previous work on the electrodeposition of the stoichiometric InSb films. The electrical properties of nanowire arrays were measured by semiconductor parameter analyzer, and the microstructural analysis of the nanowires was conducted by employing XRD. Our experimental results indicate that the InSb nanowires have a highly preferred orientation of (220) direction and also exhibit electrical characteristics of n-type semiconductors which we, however, similar to semi-metals mainly due to their narrow band-gap and high electron mobility.

Interface Dynamics during Indium Antimonide Crystal Growth

Experiments with a stoichiometric InSb compound were first performed at small temperature gradient across the crystal/melt interface of 3 °C/cm and furnace translation velocity, Vfrn, of 2 μ/sec. Known growth requirements for quality crystals were confirmed. They are, (1) the interface temperature must be close to the congruent melting temperature and, (2) the interface must be located within the adiabatic zone. These requirements can be obtained only through specific settings of the heater temperatures. An X-ray radioscopic system has been modified to accommodate real-time visualization of the crystal/melt interface during vertical Bridgman-Stockbarger growth of InSb. It is shown that asymmetric temperature settings of the heaters can be advantageously used to minimize defect formation. The interface temperature was assessed indirectly with calibrated outside thermocouples. Optical microscopy and electron microprobe analyses provided feedback on crystalline homogeneity.

Surface and Interface Properties of InSb Epitaxial Thin Films Grown on Gaas by Low Pressure Metalorganic Chemical Vapor Deposition

AbstractThere is increasing interest in the epitaxial growth of high quality InSb thin films on GaAs substrates for many device applications such as infrared optoelectronics. The large lattice mismatch (14.6%) between InSb and GaAs has meant that both growth techniques and conditions have a large influence on the interface properties and consequently the film quality. A surface science study, by X-ray photoelectron spectroscopy (XPS) and Auger electron spectroscopy (AES) together with Nomarski microscopy, on the surface and interface properties of InSb/GaAs by metalorganic chemical vapor deposition is presented. It is found fromthe XPS data that the ambient surface is composed of InSb, In2O3, Sb2O3 and Sb2O5. The interdiffusion phenomena are studied by AES depth profiling; the width of interdiffusion region is determined to be 50±10 nm for all the samples grown at different V/III ratios. This is narrower than the data previously obtained for InSb/GaAs interfaces produced by metalorganic magnetron sputtering. The results also demonstrate that uniform and stoichiometric InSb films have been obtained, and that the reproducibility of the MOCVD technique is excellent.

Heteroepitaxial growth of InSb on Si(001) surface via Ge buffer layers

InSb was grown on the Si(001), Ge(001) and Ge Si(001) substrates by the coevaporation of elemental In and Sb sources. The grown films were characterized by AES (Auger electron spectroscopy), optical microscope, XRD (X-ray diffraction), SEM (scanning electron microscope) and ECP (electron channeling pattern), as a function of growth conditions, such as growth temperature and flux ratio of Sb In . The thickness of grown InSb films was about 0.8–1.2 μm. In contrast with the direct growth on Si(001) surface, InSb easily grows heteroepitaxially on Ge(001) and Ge Si(001) substrates, for wide growth conditions. The surface morphology and the crystal quality of the grown films strongly depend on the flux and/or composition ratio of Sb In . It is found that the optimized flux ratio is about 4.5 to obtain the stoichiometric InSb films with smooth surface at growth temperature of 300°C. However, the XRD spectrum and ECP pattern reveal that better crystal quality is obtained for the In-rich films rather than the stoichiometric films.

Electrochemical growth of GaSb and InSb for applications in infra-red detectors and optical communication systems

The low-temperature electrochemical deposition of GaSb and InSb semiconductors from aqueous electrolytes has been investigated. X-ray diffraction (XRD), energy dispersive X-ray analysis (EDAX) and scanning electron microscopy (SEM) have been used to study the deposits' crystallographic and stoichiometric characteristics. Thin films of GaSb and Sb mixtures have been produced, stoichiometric control being limited by the concurrent evolution of H 2 and SbH 3. Mixtures of InSb with either Sb or In, and also mixtures of In, Sb and InSb have been grown. The type of substrate used was seen to affect the stoichiometry of the deposits. The results indicate that there are kinetic barriers to the formation of stoichiometric InSb under the conditions employed.

Formation of InSb nanocrystals on Se-terminated GaAs(001)

The effect of post-annealing on InSb island-crystal formation on Se-terminated GaAs, which is used to improve the composition ratio of Sb to In, was examined by using high-resolution scanning electron microscopy and cross-sectional transmission electron microscopy. Post-annealing after InSb growth on Se/GaAs reduces the density of nanocrystals by a factor of about 10 compared with as-grown InSb on Se/GaAs. It also increases island separation. The InSb island-crystal has a smooth terrace with edges a little higher than the inner region. The stoichiometry of nanocrystals was evaluated for the first time by using in situ synchrotron radiation photoelectron spectroscopy. Using this technique, we demonstrated that Sb incorporation occurs during post-annealing and that this drastically improves the stoichiometry of InSb nanocrystals grown on Se-terminated GaAs. As a result, we were able to obtain stoichiometric InSb nanocrystals on Se-terminated GaAs.

Cermet compact made from semiconducting InSb with constant electrical resistance in the 4–400 K range

A study of the electrophysical properties of samples prepared by phase transformation of stoichiometric InSb into lnSb-Sb-In2O3 cermet compact has been performed (InSb, In2O3-semiconductors, antimony-metallic conductivity). Samples were prepared by isothermal partial oxidation at 200–500°C for 1–50 h. Bulk and thin-film samples annealed at 400°C for 1–50 h possess relatively constant electrical resistance over the wide temperature interval measured: 4–400 K. The conversion degree, β, and molar ratio, f = In2O3/2Sb were calculated from the isothermal thermogravimetry data according to the reaction equation 2InSb+3/2O2 = In2O3+2Sb at temperatures T 400°C and t > 1 h. The X-ray powder diffraction, thermogravimetry, differential thermogravimetry and differential thermal analysis measurements and studies revealed that metallic antimony escapes partially from the InSb-Sb-In2O3 system obtained at T ≥ 400°C. As a result, the mutual volume ratio of individual InSb, Sb and In2O3 components is changed, and so also is the overall character of the electrical resistivity of the samples. Due to the partial escape of Sb↑ from the system at T ≥ 400°C, the following reaction is appropriate: 2InSb + 3/2O2 = In2O3 + (2 − z) Sb↑ = In2O3+Sb/f+ zSb, where z is the volatilized portion of Sb and f is the molar ratio of the reaction products, i.e. f = In2O3/(2 − z)Sb = 1/(2 − z). The SEM observations revealed a growing grain size with temperature and time of annealing, lowering the grain-boundary density and thus also the resistivity of the samples. The properties of the obtained ternary compact may be influenced significantly, if instead of stoichiometric InSb, the initial In-Sb with a variable In/Sb ratio is used.

Effect of recrystallization conditions on linearity of Hall output voltage of an InSb element

Recrystallizing conditions for InSb film with respect to improvement of linearity of the output voltage at Hall electrodes of the Hall element made from the recrystallized film as a function of applied magnetic flux density are studied. For recrystallization, source InSb films produced through vacuum deposition on glass substrates are covered with SiO layers, heated thoroughly into a molten phase, and then cooled to a solid phase in an Ar gas stream or vacuum. Other InSb films are covered with In2O3 layers. Uniform heating of an extensive area of the film is done in the recrystallization. Many Hall elements made from the recrystallized InSb films indicate nonlinearity output voltage as a function of the applied magnetic flux density. This phenomenon suggests that the output voltage is a result of a combination of Hall voltage and magnetoresistive voltage as Sb or In inclusions appear in the recrystallized InSb film. Superior linearity of the output voltage of the Hall element are obtained when stoichiometric InSb film is recrystallized with a relatively high cooling rate. Factors leading to excellent linearity are verified through x-ray diffractometry, fluorescent x rays, and microscopic examinations on the recrystallized InSb films and the source InSb films. In this paper, Sb and In inclusion structures in the recrystallized InSb films are discussed and the causes of linearity or nonlinearity are explained using the above experimental examinations.

Synthesis of stoichiometric InSb thin films by a simple molecular-beam technique

In-Sb alloy films, deposited by a two-source molecular-beam technique at substrate temperatures from 500 to 700 K in ultrahigh vacuum, have been examined by Auger electron spectroscopy. The compositional analysis shows that incident atoms of In and Sb react promptly to stabilize as the compound InSb. The stoichiometry of the deposits is disturbed when the surface is saturated with the residual free atoms. The stoichiometric InSb films can be deposited under the beam-intensity condition that JIn&amp;lt;JSb&amp;lt;JIn+n,n (T) =1.6×1029 exp(−2.3×104/T) atoms/cm2 s, where n corresponds to the critical beam intensity for the condensation of antimony.