Effects of rapid thermal annealing on the morphology and optical properity of ultrathin InSb film deposited on SiO2/Si substrate

Ultrathin InSb thin films on SiO₂/Si substrates are prepared by radio frequency (RF) magnetron sputtering and rapid thermal annealing (RTA) at 300, 400, and 500℃, respectively. X-ray diffraction (XRD) indicates that InSb film treated by RTA at 500℃, which is higher than its melting temperature (about 485℃), shows a monocrystalline-like feature. High-resolution transmission electron microscopy (HRTEM) micrograph shows that melt recrystallization of InSb film on SiO₂/Si(111) substrate is along the (111) planes. The transmittances of InSb films decrease and the optical band gaps redshift from 0.24 eV to 0.19 eV with annealing temperature increasing from 300℃ to 500℃, which is indicated by Fourier transform infrared spectroscopy (FTIR) measurement. The observed changes demonstrate that RAT is a viable technique for improving characteristics of InSb films, especially the melt-recrystallized film treated by RTA at 500℃.     

Classical in-plane negative magnetoresistance and quantum positive magnetoresistance in undoped InSb thin films on GaAs (1 0 0) substrates

Magnetoresistance (MR) effects have been investigated in perpendicular and parallel magnetic fields at 300, 80 K and liquid He temperatures for undoped InSb thin films 0.1–2.3 μm thick grown on GaAs(1 0 0) substrates by MBE. At high temperatures, the intrinsic carriers show the parabolic negative MR observable only in magnetic fields parallel to the film. The skipping-orbit effect due to surface boundary scattering in the classical orbits in the plane vertical to the film has been argued to be responsible for the negative MR. At low temperatures (T=80 K), the transport is dominated by the two-dimensional (2D) electrons in the accumulation layers at the InSb/GaAs(1 0 0) hetero interface; MR is positive and shows a logarithmic increase with anisotropy between parallel and perpendicular field orientation, arising from the 2D weak anti-localization (WAL) that reflects the interplay between the spin-Zeeman effect and strong spin–orbit interaction caused by the asymmetric potential at the interface (Rashba term). The zero-field spin splitting energy of Δ₀13 meV, the electron effective mass of m^*0.10m₀ seven times of the band edge mass in bulk InSb and the effective g-factor of |g^*|15 in the accumulation layer have been inferred from fits of MR for the 0.1 μm thick film to the 2D WL theory.     

X-ray diffraction from the ripple structures created by femtosecond laser pulses

In this paper, we present the investigation and characterization of the laser-induced surface structure on an asymmetrically cut InSb crystal. We describe diffraction from the ripple surface and present a theoretical model that can be used to simulate X-ray energy scans. The asymmetrically cut InSb sample was irradiated with short-pulse radiation centred at 800 nm, with fluences ranging from 10 to 80 mJ/cm². The irradiated sample surface profile was investigated using optical and atomic force microscopy. We have investigated how laser-induced ripples influence the possibility of studying repetitive melting of solids using X-ray diffraction. The main effects arise from variations in local asymmetry angles, which reduce the attenuation length and increase the X-ray diffraction efficiency.     

Effects of In and Sb mono-layers to form rotated InSb films on a Si(1 1 1) substrate

A new method for InSb heteroepitaxial growth on a Si substrate was introduced in our previous work, in which an InSb film was formed via an InSb bi-layer. In the present work, to study the effects of In and Sb individual layers on the InSb film quality, InSb was deposited onto an InSb bi-layer, In mono-layer, and Sb mono-layer on a Si substrate. It was found that both In and Sb layers (in other words, InSb bi-layer) were essential to form a fine InSb film.     

AES, EELS and TRIM investigation of InSb and InP compounds subjected to Ar ions bombardment

The interaction of ions with matter plays an important role in the treatment of material surfaces. In this paper we study the effect of argon ion bombardment on the InSb surface in comparison with the InP one. The Ar⁺ ions, accelerated at low energy (300 eV) lead to compositional and structural changes in InP and InSb compounds. The InP surface is more sensitive to Ar⁺ ions than that of InSb. These results are directly inferred from the qualitative Auger electron spectra (AES) and electron energy loss spectroscopy (EELS) analysis. However, these techniques alone do not allow us to determine with accuracy the disturbed depth in Ar⁺ ions of InP and InSb compounds. For this reason, we combine AES and EELS with the simulation method TRIM (transport and range of ions in matter) to show the mechanism of interaction between the ions and the InP or InSb and hence determine the disturbed depth as a function of Ar⁺ energy.     

(InSb/GaAs)-Au hybrid macro-structure prepared by flash evaporation

n-Type indium antimonide-Au hybrid macro-structure was successfully fabricated on p-GaAs substrate by a simple and economic flash evaporation technique. The elemental composition of the prepared InSb film was confirmed by energy dispersive X-ray spectroscopy microanalysis (EDX). The surface topography and crystal structure of the InSb film was characterized by scanning electron microscopy (SEM) and X-ray diffraction (XRD), respectively. The magnetoresistance of the prepared hybrid macro-structure was measured and discussed in terms of the model of current redistribution.     

Melting properties of group-V elements and InSb

Summary In this paper, we study the structural properties of liquid group-V elements (and a compound InSb) and we analyse the differences with their room temperature crystalline phases. Neutron diffraction experiments are performed using short-wavelength neutrons (0.7 ?). We show different melting behaviours of a light element (As) and a heavy element (Sb) under study. Whereas As keeps its coordination three upon melting, Sb is six-coordinated in the melt. Similarly, InSb has a coordination number increasing from 4 to about 6 upon melting. Large entropies of melting are related to important structural variations. Paper presented at the workshop ?Highlights on Simple Liquids?, held in Turin at ISI on 1–3 May, 1989.     

Weak-field magnetoresistance anomaly and Shubnikov–de Haas oscillations in Sn-doped InSb thin films on GaAs (100) substrates

Distinctive magnetoresistance (MR) effects in weak magnetic fields before the appearance of Shubnikov–de Haas (SdH) oscillations at low temperatures in Sn-doped (7×10¹⁶ cm⁻³) InSb films grown on GaAs(100) substrates by MBE have been investigated with decreasing film thickness d from 1 μm. The negative MR found in weak magnetic fields for d0.5 μm can be broadly divided into two regimes: T-sensitive negative MR below B_c observed with anisotropy between parallel and perpendicular magnetic field and a T-insensitive parabolic one above B_c observable only under in-plane magnetic fields. The latter is ascribable to the skipping orbit effect due to surface boundary scattering. In vanishing magnetic fields far below B_c, the negative MR reduces with decreasing d and the different positive MR overlaps with it below 0.5 μm, eventually dominating the positive MR at d0.2 μm. These results have been analyzed using a two-layer model for the films, where the composition of the upper layer under the surface and the lower one adjacent to the InSb/GaAs interface is assumed. The MR data in the extremely weak magnetic fields below 100 G for each layer have been successfully fitted to the two-dimensional (2D) weak localization (WL) theory. These results explain that the crossover from the 2D WL to the weak anti-localization (WAL) occurs when the interface is approached with the increase of SO interaction in the layers caused by the increased influence of the asymmetric potential at the hetero interface (Rashba term) and the SO rate in the intrinsic InSb film due to the crystal field of the zinc-blende structure (Dresselhaus term) is as small as τ_so⁻¹3×10⁸ s⁻¹.     

Effects of doping and preliminary processing on the magnetically stimulated mobility of dislocations in InSb single crystals

The effect of the type of conductivity and the doping level of InSb single crystals on the mobility of fast 60° dislocations in a magnetic field is discovered. It is found that doping of a pure InSb crystal with tellurium (n-type impurity) to 10¹⁸ cm^?3 reduces the mobility of dislocations to the background level. At the same time, in p-type InSb crystals doped with Ge with the same carrier concentration (10¹⁸ cm^?3), the magnetoplastic effect is manifested clearly. It is shown that preliminary mechanical loading and, hence, internal stresses in the crystal affect not only the mean path length of dislocations in a magnetic field but also the magnitude of the threshold magnetic field below which the magnetoplastic effect is not observed. Possible reasons for these phenomena are discussed.     

Spin-flip Raman scattering from electrons in localized donor states in n-InSb

We report the first observation of spin-flip Raman scattering from electrons localized in shallow donor states in InSb. For a non-degenerate n-InSb sample (8×10¹³ cm^-3) measurements of the spin-flip Raman gain and the effective g-value as a function of the magnetic field show lineshapes and magnetic field dependences completely different to that of an InSb sample with the electron gas being in a degenerate regime (1.35×10¹⁵ cm^-3). For the 8×10¹³ cm^-3 InSb sample, at magnetic fields greater than 11.5 kG, a splitting of the spin-flip Raman line into two lines is observed which may be an indication that two shallow donor states with different effective g-values are concerned.     

Negative photoconductance in thin indium antimonide films

Negative photoconductance or optical quenching has been observed in thin InSb films, fabricated by vacuum evaporation on glass substrates. An electronic flash was used as the light source. The time constant of the photocurrent measured on several samples ranges from 30 sec to 3 min. Whereas bulktraps localised in the narrow band gap of InSb (0.18 eV) can hardly be responsible for the high time constants, it is believed that slow surface traps or traps inside an In₂O₃ layer, covering the InSb film, are responsible for the optical quenching.     

InSb中离子注入二次缺陷研究

本文用平面的透射电子显微术(TEM)、剖面的透射电子显微术(XTEM)以及卢瑟福背散射和沟道谱(RBS),研究InSb中离于注入Zn⁺,Mg⁺,Be⁺产生的二次缺陷。以及它们的退火特性。结果表明,轻离子Be⁺注入产生的二次缺陷比重离子Zn⁺注入产生的要少得多,而Mg⁺离子介于Be⁺离子和Zn⁺离子之间,在中等剂量下(1×10¹³cm^-2附近),注入损伤并不严重,而且容易恢复。从360℃到440℃之间作了退火温度的研究。从研究结果发现,退火温度以360℃为佳。离子注入InSb中的二次缺陷的形貌与Si中的不同,InSb中的二次缺陷以位错网为主,位错环所占比例不大且尺寸较小,而沉淀物和层错四面体也出现在其中。 关键词：     

Photodiode properties of molecular beam epitaxial InSb on a heavily doped substrate

Photodiodes of InSb were fabricated on an epitaxial layer grown using molecular beam epitaxy (MBE). Thermal cleaning of the InSb (0 0 1) substrate surface, 2° towards the (1 1 1) B plane, was performed to remove the oxide. Photodiode properties of МВЕ-formed epitaxial InSb were demonstrated. Zero-bias resistance area product (R₀A) measurements were taken at 80 K under room temperature background for a pixel size of 100 μm × 100 μm. Values were as high as 4.36 × 10⁴ Ω/cm², and the average value of R₀A was 1.66 × 10⁴ Ω/cm². The peak response was 2.44 (A/W). The epitaxial InSb photodiodes were fabricated using the same process as bulk crystal InSb diodes with the exception of the junction formation method. These values are comparable to the properties of bulk crystal InSb photodiodes.     

InSb quantum dots and quantum rings on InAs-rich surface

We report a study of InSb nanoobjects (quantum dots and quantum rings) grown on InAs-rich surface by liquid phase epitaxy. Characterization of the sample surface was performed using atomic force microscopy (AFM). The bimodal formation of the uncapped InSb quantum dots (QDs) was observed for the growing on a binary InAs substrate. Uniform high-density (1 × 10¹⁰ cm⁻²) quantum dots with a height of 3 nm were obtained at T = 420-430 °C, whereas low-density (5 × 10⁸ cm⁻²) big quantum dots were 9 nm in height. As a buffer layer, lattice-matched InAsSb_0.12P_0.25 solid solution was deposed on InAs substrate using metal-organic vapour phase epitaxy. Deposition from the InSb melt on the buffer layer resulted in the formation of InSb nanoobjects with density as high as 3 × 10¹⁰ cm⁻².     

Interface of anodic sulfide-oxide on n-type InSb

A novel anodic sulfidization process for forming native sulfide-oxide films on n-type InSb is described. The results of Auger electron spectroscopy analysis indicate that native sulfide-oxide films are formed from aqueous sulfide solutions. The measured capacitance-voltage characteristics of metal-insulator-semiconductor devices indicate that the films have a low fixed surface charge density of the order of 3×10¹⁰ cm^–2 and small hysteresis. The native sulfide-oxide films leave the surface of n-type InSb practically at flatband and in this respect are superior to the passivation layers of anodic oxide and direct plasma SiN _x . The interface between InSb and its native sulfide-oxide in combination with plasma CVD SiN _x has excellent electrical properties.     

Response functions for surface polaritons at interfaces in solids

Surface excitations of phonon and plasmon character are reviewed and discussed using the electric field response function. Calculations of the surface mode dispersion curves are exhibited for InSb for carrier concentrations in the 1 to 6 × 10¹⁷ cm^?3 range. Some comparisons are made with the reflectivity data of Anderson et al. which confirm the presence of a damaged layer on their InSb samples.     

液态InSb电阻率和热电势与温度的关系

利用直流四电极法和微差法分别测量了液态InSb的电阻率和热电势与温度的关系,得到了高精度的数据.发现液态InSb的电阻率温度系数在熔点附近随温度升高而增大;在高于617℃的高温区,该液体的电阻率与温度呈较好的线性关系.热电势温度系数在617℃左右也同样存在较明显的变化.结合其他物理性质随温度的变化规律及接近熔点温度的结构特点,可以认为液态InSb在熔点以上存在结构变化. 关键词： 电阻率 热电势 液态InSb 结构转变     

On the stability of pseudomorphic α-Sn on InSb(001) to temperature and film thickness

Thin films of α-Sn deposited on InSb(001) at 160°C have been studied. The films, grown to a total thickness of 80 Å, showed similar but more pronounced diffraction peaks compared to a monolayer of α-Sn on InSb grown at 30°C. A film of 80 Å was shown to change its behaviour at ∼ 181°C. It is believed to collapse to β-Sn imbedded in a thin film of α-Sn.     

Enhanced optical nonlinearities of superlattices within the Kronig-Penney model incorporating inherent bulk nonlinearities

Third order nonlinear optical susceptibilities χ⁽³⁾ of GaAs/Ga_1?xAlAs superlattices have been predicted which are two orders of magnitude larger than those of bulk GaAs. This enhancement is due to the band nonparabolicity arising from the additional periodicity of the superlattice. These predictions, based on a tight-binding model of the superlattice dispersion, are here extended to the more realistic Kronig-Penney (KP) model. Corrections to tight-binding are non-negligible; however, enhancements of χ⁽³⁾ are still large but reduced approximately 30%–50% over previous estimates. The KP model is also here applied to superlattices employing InSb as the quantum well material. Because of the smaller effective mass of InSb, and taking account of its bulk nonparabolicity, the minibands move to higher energy, enhancing the interwell overlap and increasing χ⁽³⁾ by about one order of magnitude over that of bulk InSb. The role of the barrier material in this case is important and is discussed. The interplay between the bulk nonparabolicity and that arising from the superlattice is also addressed.     

Temperature dependence of terahertz radiation from n-type InSb and n-type InAs surfaces

The azimuthal angle dependence and the temperature dependence of terahertz (THz) radiation generated from n-type (111) InSb and n-type (111) InAs surfaces irradiated with ∼80 fs near-infrared laser pulses are investigated. The azimuthal angle dependence shows that the contribution of the difference-frequency mixing (DFM) is not dominant for both materials at the excitation density of ∼1 GW/cm². At an appropriate azimuthal angle, the radiation due to DFM is excluded from the total THz radiation and the temperature dependence of THz radiation due to the surge current is observed. The increase of THz radiation with decrease of the temperature is found to be much more pronounced for InSb than for InAs. The different temperature dependence can be attributed to the different radiation mechanisms dominant for both materials. Especially, the temperature dependence of the THz radiation from InSb is well explained by the photo-Dember effect. Received: 9 May 2000 / Revised version: 17 August 2000 / Published online: 5 October 2000