InSb Single Crystals Research Articles

Catalyst-free in-plane growth of high-quality ultra-thin InSb nanowires

InSb nanowires (NWs) show an important application in topological quantum computing owing to their high electron mobility, strong spin–orbit interaction, and large g factor. Particularly, ultra-thin InSb NWs are expected to be used to solve the problem of multiple sub-band occupation for the detection of Majorana fermions. However, it is still difficult to epitaxially grow ultra-thin InSb NWs due to the surfactant effect of Sb. Here, we develop an in-plane self-assembled technique to grow catalyst-free ultra-thin InSb NWs on Ge(001) substrates by molecular-beam epitaxy. It is found that ultra-thin InSb NWs with a diameter as small as 17 nm can be obtained by this growth manner. More importantly, these NWs have aspect ratios of 40–100. We also find that the in-plane InSb NWs always grow along the [110] and [11¯0] directions, and they have the same {111} facets, which are caused by the lowest-surface energy of {111} crystal planes for NWs grown with a high Sb/In ratio. Detailed structural studies confirm that InSb NWs are high-quality zinc blende crystals, and there is a strict epitaxial relationship between the InSb NW and the Ge substrate. The in-plane InSb NWs have a similar Raman spectral linewidth compared with that of the single-crystal InSb substrate, further confirming their high crystal quality. Our work provides useful insights into the controlled growth of in-plane catalyst-free III–V NWs.

Generation of a coherent longitudinal optical phonon plasmon coupled mode in an n-type InSb single crystal in the absence and/or strong suppression of the photo-Dember effect confirmed with the use of terahertz time-domain spectroscopy

We explored the feasibility of generating a coherent longitudinal optical (LO) phonon–plasmon coupled mode in an n-type InSb single crystal with the condition that the photo-Dember effect is strongly suppressed and/or eliminated. We systematically performed terahertz time-domain spectroscopic measurements of the n-type InSb single crystal and undoped InSb crystal. The terahertz electromagnetic wave originating from the photo-Dember effect was extinguished in the n-type InSb single crystal, while the clear signal from the photo-Dember effect was detected in the undoped InSb single crystal. Meanwhile we detected the clear signal of the terahertz wave from the coherent LO-phonon–plasmon coupled mode in the n-type InSb single crystal, indicating that the photo-Dember effect is not dominant in the generation of the coherent LO-phonon–plasmon coupled mode although the photo-Dember effect has been attributed to the dominant generation mechanism of the coherent LO-phonon–plasmon coupled mode so far. We explain the present phenomenon, taking account of the fact that the impulsive stimulated Raman scattering process has a possibility of generating coherent LO-phonon–plasmon coupled modes in light-absorbing solids [Nakamura et al., Phys. Rev. B 99, 180301(R) (2019)].

Effect of chemical bond polarity on wafer and cleavage surface oxidation for GaAs, GaSb, InAs and InSb single crystals

Rapid development of III–V semiconductor device technologies and broadening of device applications are hindered by the high density of surface states produced in those materials by intrinsic complex oxides and surface contaminations. Surface oxides acting as non-radiating recombination centers produce a number of surface levels in the band gap. Oxidation mechanisms depend on the chemical composition of a specific III–V semiconductor compound because surface reactivities differ between materials. The effect of chemical bond polarity on surface oxidation processes in single crystal III–V semiconductor wafers is currently an important research topic. In this work, surface-sensitive XPS method has been used for studying oxidation regularities in GaAs, InAs, GaSb and InSb single crystals undergoing natural atmospheric oxidation and subjected chemical-mechanical polishing. A method of assessing oxidation levels based on chemical shifts of XPS spectral features has been developed. Oxidation level has been shown to depend on chemical bond ionicity degree, the latter being evaluated using the Sanderson and Phillips models. A decrease in surface oxidation level with an increase in bond ionicity degree has been observed for (110) single crystal wafer cleavage surfaces and for (100) single crystal wafer surfaces after single crystal slicing and chemical-mechanical polishing. We show that surface oxidation level increases in the InAs–GaAs–InSb–GaSb sequence, from arsenides to antimonides.

InSb ФОТОДІОДИ (ОГЛЯД. ЧАСТИНА VI)

In this review, a brief overview of epitaxial methods of growing single-crystal InSb films and their application for the manufacture of infrared photodiodes is provided. The results of growing InSb epitaxial films on Si and GaAs substrates are described. The main attention in the review is paid to InSb/CdTe heterostructures, which is explained by the almost perfect matching of their lattices and coefficients of thermal expansion. The properties of heterovalent InSb/CdTe interfaces as promising objects for spintronics and topological insulators are described. The results of experimental studies of InSb photodiodes for the mid-wavelength region of 3-5 μm, passivated with polycrystalline CdTe films by the hot wall epitaxy method are given. To investigate the electrical properties of polycrystalline fims, the direct conductivity was measured as a function of bias voltage and temperature. For this purpose, polycrystalline fims with a thickness of 200 to 1800 nm were grown on p-InSb substrates. The type of conductivity and resistivity of polycrystalline films were determined. Conclusions were made regarding the possibility of using this technique for effective and stable passivation. Photodiodes were characterized by measuring the dark current and the lifetime of minor carriers. Properties of heterovalent CdTe/InSb and isovalent CdTe/HgCdTe interfaces are compared. It is shown that they have different effects on the transport and photoelectric characteristics of photodiodes. It was established that when the passivation layer is deposited on the chemically etched surface of the mesa, an excess current of tunneling nature occurs in the photodiodes. The best results were obtained when surface treatment of the mesa includes the use of CP4A and HCl etchants, sulfidization in a non-aqueous Na 2 S solution, and deposition of a CdTe protective layer. Passivation of HgCdTe photodiodes using polycrystalline CdTe films does not affect the lifetime of charge carriers, but it needs improvement to achieve better stability of their characteristics.

Investigation of the Strength Properties of Single-Crystal InSb Depending on Crystallographic Orientation and Growth Conditions

Investigation of the Strength Properties of Single-Crystal InSb Depending on Crystallographic Orientation and Growth Conditions

Study of indium antimonide single crystals obtained by the modernized Chokhralsky method in several crystallographic directions

Single-crystal indium antimonide InSb is an indispensable material in such branches of solid-state electronics as opto- and nanoelectronics. In turn, the dislocation density and the character of their distribution, which directly depend on the technological parameters of the growth process, considerably determine the physical and mechanical properties of the material. We present the results of studying InSb single crystals obtained by the modernized Czochralski method in the crystallographic directions [100], [111], and [112]. The effect of growth conditions (axial and radial temperature gradients at the crystallization front) on the dislocation structure of InSb plates and the structural properties of the plates were analyzed. Using the method of selective etching it was shown that the number of etching pits on the wafers with different orientations differs by approximately an order of magnitude (103 cm–2 for plane (111) and 102 cm–2 for (100)). Number of etch pits for the (100) plane is commensurate with their number in crystals grown in the [112] and [100] directions. Probably, the maximum dislocation density in InSb single crystals can be considered as a material constant, and the increased strength of single crystals grown at lower axial gradients at the crystallization front is related to the formation of a characteristic ensemble of point defects along the dislocation line through diffusion. It is shown that InSb wafers [112] (100) exhibit the best physical and mechanical properties. The results obtained can be used in the manufacture of structures for photodetectors, in particular, in plate processing (cutting, grinding and polishing) to optimize technological processes.

Chemical interaction of the GaAs, GaSb, InAs, and InSb single crystals surface with I2 + DMF (methanol) etchants

Chemical interaction of the GaAs, GaSb, InAs, and InSb single crystals surface with I2 + DMF (methanol) etchants

Shear induced deformation twinning evolution in thermoelectric InSb

Twin boundary (TB) engineering has been widely applied to enhance the strength and plasticity of metals and alloys, but is rarely adopted in thermoelectric (TE) semiconductors. Our previous first-principles results showed that nanotwins can strengthen TE Indium Antimony (InSb) through In–Sb covalent bond rearrangement at the TBs. Herein, we further show that shear-induced deformation twinning enhances plasticity of InSb. We demonstrate this by employing large-scale molecular dynamics (MD) to follow the shear stress response of flawless single-crystal InSb along various slip systems. We observed that the maximum shear strain for the (111)[11bar 2] slip system can be up to 0.85 due to shear-induced deformation twinning. We attribute this deformation twinning to the “catching bond” involving breaking and re-formation of In–Sb bond in InSb. This finding opens up a strategy to increase the plasticity of TE InSb by deformation twinning, which is expected to be implemented in other isotypic III–V semiconductors with zinc blende structure.

Magnetic Resistance Sensory System for the Quantitative Measurement of Morphine.

Point-of-care testing (POCT) is characterized by fast detection, simple use, and cost efficiency. As the focus of healthcare shifts to precision medicine, population health, and chronic disease management, the potential impact of POCT has increased significantly in the past decade. Immunochromatographic test strips (ICTSs) are currently the most promising POCT diagnostic format due to the advantages of fast detection, simple operation and cost-effective. The lateral flow immune analyzer (LFIA) system that uses magnetic resistance (MR) sensors as readers and magnetic nanoparticle labeling materials has attracted wide attention due to its high sensitivity and specificity. This paper designs a quantitative lateral flow immunoassay instrument for MR sensors using InSb single crystals as magnetoresistive elements. MR sensors detect samples of ICTSs labeled with superparamagnetic nanoparticles (SMNPs). The collected weak magnetic signal is processed by the designed amplifying circuit and software algorithm. As a result, the MR system can quantitatively detect the concentration of morphine (MOP), and has good repeatability. Compared with other optical detection instruments, the system has good specificity because there is very low background noise in the detection sample. The size of the whole system is [Formula: see text], and it has the characteristics of compactness and fast detection.

Effect of mechanical treatment type on the strength of undoped single crystal indium antimonide wafers

Thin (100) wafers of single crystal undoped InSb have been strength tested by plane transverse bending. The strength of the wafers (≤ 800 mm in thickness) has been shown to depend on their mechanical treatment type. If the full mechanical treatment cycle is used (grinding + chemical polishing) the strength of the InSb wafers increases twofold (from 3.0 to 6.4 kg/mm2). We show that the strength dependence on mechanical treatment type for (100) wafers is similar to that for (111) wafers, the strength of (111) wafers being 2 times higher. The roughness of the thin wafers after the full mechanical treatment cycle has been measured using contact profilometry. After the full mechanical treatment cycle the roughness of the InSb wafers Ra decreases from 0.6 to 0.04 mm leading to general surface smoothening. We have compared the strength and roughness between (100) InSb and GaAs wafers. The roughness of InSb and GaAs wafers after the full mechanical treatment cycle decreases significantly: by 10 times for InSb due to the general surface smoothening and by 3 times for GaAs (Rz from 2.4 to 0.8 mm) due to a reduction of the peak roughness component. The full mechanical treatment cycle increases the strength of InSb wafers by removing damaged layers through the sequence of operations and reducing the risk of mechanical damage development.

Chemical dissolution of GaAs, InAs, InAs (Sn), GaSb and InSb single crystals in H2O2–HBr–tartaric acid etching compositions

Chemical dissolution of GaAs, InAs, InAs (Sn), GaSb and InSb single crystals in H2O2–HBr–tartaric acid etching compositions

Atomic-level calculations and experimental study of dislocations in InSb

Plastic deformation in InSb single crystals is governed by the motion of dislocations. Since InSb has a diamond cubic lattice, it possesses two sets of slip planes: a shuffle set and a glide set. Transmission electron microscopy analysis of deformed bulk single crystals shows that, at low temperatures (<20 °C), dislocations have narrow cores, while at higher temperatures, they have extended cores. However, it remains unclear to which slip plane set these dislocations belong. In this paper, by combining experiments and atomic-level calculations, we show that dislocations with narrow and extended cores, respectively, belong to the shuffle and glide sets. The conclusion is reached by calculating the generalized stacking fault energy curves and ideal shear stresses using density functional theory calculations and the intrinsic stacking fault width associated with dislocations using atomistic simulations. It is also found that while the shuffle set dislocations are easier to activate at lower temperatures, dislocations on the glide set become dominant at higher temperatures.

The effect of magnetic field direction on thermoelectric and thermomagnetic coefficients of undoped single crystalline InSb at room temperature

Thermoelectric and thermomagnetic coefficients were calculated for n-type undoped InSb single crystals through a temperature range from 10°C up to 80°C and magnetic fields from -0.6T to 0.6T. The thermoelectric Seebeck coefficient varied only with the temperature gradient, while the thermomagnetic Nernst coefficient varied with both the temperature gradient and the magnetic field. This paper also investigated the effects of the incident angle of magnetic field on the InSb sample surface with regard to the values of thermoelectric and thermomagnetic coefficients; the results showed that thermoelectric and thermomagnetic coefficients were independent of magnetic field direction.

Anomalous magnetic and transport properties of InSb(Mn) crystals near metal-insulator transition

In Mn-doped InSb single crystals an unusual, for nonmagnetic semiconductors, dependence on manganese concentration have been revealed for magnetization, conductivity, magnetoresistance and the Hall effect in the range NMn= (1÷2)×1017cm-3. Noticeable low temperature magnetization increase was observed at NMn≈1×1017cm-3. Strong correlation between magnetization, specific resistivity, Colossal Magnetoresistance (CMR) and the Hall constant as a function of manganese concentration in InSb(Mn) was revealed on the insulating side of the metal-insulator transition at Ncr=2×1017cm-3 and at temperature below 10K. Simultaneously, an onset of ferromagnetic-like response in the magnetic moment measurements of p-InSb(Mn) at NMn≤Ncr= 2×1017 cm-3 was registered. This experimental evidence fits the pattern of triplet excitons switching off from conductivity and demonstrates weak magnetic ordering. The coincidence in transport, magnetotransport properties of p-InSb(Mn) and uniaxially stressed p-InSb(Ge) crystals puts forward the idea that the unusual InSb(Mn) properties could be related to Jahn-Teller distortions caused by Mn.

MBE-grown InSb photodetector arrays

The MBE method has been applied to grow InSb layers on InSb substrates. These layers have served as a basis for fabricating mid-wave IR photodetector arrays. The characteristics of photodetector arrays on epitaxial InSb layers have been compared with those of series-produced single-crystal InSb arrays.

Magnetoresistance of electrochemically produced InSb

Classical geometric effects in disordered and inhomogeneous polycrystalline narrow bandgap semiconductors can lead to high, non-saturating, linear magnetoresistance (MR) values. It has been previously shown that polycrystalline networks of InSb produced by grinding an InSb single crystal have a large, linear, non-saturating magnetoresistance of several hundred per cent. InSb produced via electrochemical routes has not been characterised regarding their magnetoresistive response yet. Starting from a material produced by an electroless solution-phase reaction, we demonstrate that despite small crystallite size and inhomogeneous material composition, a similar effect leading to a high, linear and non-saturating MR of up to 150% can be observed. A range of InSb thin films produced via electrodeposition show much lower MR values of ∼2% and a non-linear magnetic field dependence probably due to resulting microstructure and use of a conductive substrate.

Growth of eutectic composites in the InSb–MnSb system

Eutectic composites in the InSb–MnSb system have been grown by the Bridgman method in vertical geometry using a growth charge of eutectic composition. The composites consisted of a [110]-oriented single-crystal InSb matrix and single-crystal MnSb needles aligned in the growth direction. As the solidification rate was raised from 0.5 to 6 mm/h, the length of the needles increased, whereas their diameter dropped from 20 to 4 µm. Further raising the solidification rate led to spontaneous crystallization. Characteristically, the electrical and magnetic properties of the eutectic composites in the InSb–MnSb system were found to exhibit large anisotropy. The low-temperature resistivity of the composites across the needles is four to five times that along the needles. With increasing temperature, the resistivity ratio drops by up to a factor of 2–3. This can be accounted for in terms of a geometric factor. The electrical conductivity of the composites is determined primarily by the MnSb phase, whose volume along the growth direction was considerably larger. According to magnetic measurements, the eutectic composites in the InSb–MnSb system are ferromagnets with a Curie temperature of ≃ 600 K.

INVESTIGATION ON THE PROPERTIES OF LARGE [100]−ORIENTED INSB SINGLE CRYSTALS GROWN BY CZOHRALSKI METHOD

Investigation on the properties of large [100]−oriented InSb single crystals grown by Czoсhralski method The properties of undoped and heavily Te doped large single crystals of InSb grown by Czochralski method in the [100] direction and intended for use in IR photodetectors of new generation were studied. It was found that the non−uniformity in undoped crystals does not exceed 10—16%. The average dislocation density in this ingots was 7 101 cm−2 and their distribution along the diameter of (100)−oriented wafers was much more uniform than for the (211)−oriented wafers. We also studied the microstructure of heavily Te doped InSb crystals. It was established that the dislocation density in these crystals was below 1 102 cm−2. Te doping producing the electron concentration higher than 1,5 ⋅ 1018 cm−3 gave rise to the formation of high density of precipitates. The optical transmission of the samples with electron concentration ~6,9 ⋅ 1017 cm−3 was found to de higher 40 % for the wavelength range of 3—5 µm

Shock-recovery studies on InSb single crystals up to 24 GPa

A series of shock-recovery experiments on InSb single crystals along the (100) or (111) axes up to 24 GPa were performed using flyer plate impact. The structures of recovered samples were characterized by X-ray diffraction (XRD) analysis. According to calculated peak pressures and temperatures, and phase diagram for InSb, the sample could undergo phase transitions from zinc-blende structure to high-pressure phases. However, the XRD trace of each sample corresponded to powder pattern of InSb with zinc-blende structure. The XRD trace of each sample revealed the absence of additional constituents including metastable phases and high-pressure phases of InSb except for samples shocked around 16 GPa. At 16 GPa, in addition to zinc-blende structure, additional peaks were obtained. One of these peaks may correspond to the Cmcm or Immm phase of InSb, and the other peaks were not identified.

Diamond turning of small Fresnel lens array in single crystal InSb

A small Fresnel lens array was diamond turned in a single crystal (0 0 1) InSb wafer using a half-radius negative rake angle (−25°) single-point diamond tool. The machined array consisted of three concave Fresnel lenses cut under different machining sequences. The Fresnel lens profiles were designed to operate in the paraxial domain having a quadratic phase distribution. The sample was examined by scanning electron microscopy and an optical profilometer. Optical profilometry was also used to measure the surface roughness of the machined surface. Ductile ribbon-like chips were observed on the cutting tool rake face. No signs of cutting edge wear was observed on the diamond tool. The machined surface presented an amorphous phase probed by micro Raman spectroscopy. A successful heat treatment of annealing was carried out to recover the crystalline phase on the machined surface. The results indicated that it is possible to perform a ‘mechanical lithography’ process in single crystal semiconductors.