InSb Films Research Articles

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.

KINETIC MONTE CARLO SIMULATION OF HETEROEPITAXIAL GROWTH OF InSb BUFFER LAYER AND EFFECTS ON InSb/GaAs FILMS

InSb films on GaAs (001) substrates have been grown using a two-step method by molecular beam epitaxy (MBE). The Kinetic Monte Carlo (KMC) method, based on solid-on-solid (SOS) model has been introduced to simulate the Volmer–Weber growth of InSb buffer layer on GaAs substrate. The buffer surface becomes rough obviously and produces an undulating profile during the last coverage of the substrate. The undulating buffer surface would play an adverse role in the surface morphology of the following InSb epilayer. Therefore, the growth of InSb epilayer before the formation of undulating buffer surface would get a better surface, which has been convinced by the results of atomic force microscope (AFM) observations.

Fabrication and electrical characterization of n-InSb on porous Si heterojunctions prepared by liquid phase epitaxy

Thin films of InSb were grown on p-type porous silicon (PSi) (111) substrates by liquid phase epitaxy (LPE) to obtain monocrystalline InSb epilayer on a PSi substrate for low cost device applications. The structural characterization of the devices was carried out by X-ray diffraction (XRD) and scanning electron microscopy (SEM). The X-ray diffraction measurements indicate that InSb monocrystalline epilayer was successfully grown onto PSi. The current–voltage (I–V) characteristics of n-InSb/p-PSi heterojunction devices were measured in the temperature range of 298–398K. The measurements indicate that these heterojunctions have good rectifying characteristics. The estimated zero-bias barrier height ϕBO and the ideality factor η show strong temperature dependence. The conventional Richardson plot exhibits linear behavior in the entire temperature range indicating that the conduction seems to be predominantly due to thermionic emission mechanism. In addition, the capacitance-voltage characteristics are investigated at frequency of 1MHz. The built-in potential of the heterojunction is determined after eliminating the effect of the capacitance effect of the interface state caused by the lattice mismatch.

Temperature dependence of optical constants for InSb films including molten phases

We have measured the temperature dependence of optical constants of InSb films including molten phases. It has been found that the optical constants differ between the as-sputtered amorphous and the molten states. Also, the optical constants exhibit the large change associated with the crystalline-to-molten phase transition. In the crystalline states, the extinction coefficient increases as the temperature increases. This temperature dependence can be explained by the decrease of the band gap energy.

Growth and Characterization of InSb films on Si (001)

ABSTRACTThe replacement of native oxides with deposited oxides in CMOS technology opens the door to replacing the Si with semiconductors without high-quality native oxides. For example, the use of InSb in logic applications could allow much lower operating voltages and power dissipation due to the InSb channels reaching saturation at significantly lower electric fields. Epitaxy of InSb onto Si could be done directly or using an intermediate layer such as GaP, GaAs, or InP. In the current work we describe the growth of InSb on Si (001) and discuss the structural and electrical properties of the resulting InSb films. The samples were characterized in terms of background electron concentration, mobility, deep level traps, Hall sensitivity, and x-ray rocking curve width.Samples were grown using molecular-beam epitaxy in a Riber-Compact 21T system. Antimony was supplied with a Veeco valved cracker cell. Vicinal Si(001) substrates offcut by 4º toward [110] were prepared by repeated oxidation and oxide-removal and then loaded into the MBE system. After the substrate temperature had been increased to about 820ºC, the surface shows a clear 24 reconstruction and appears to be free of oxide. This reconstruction remains until the substrate temperature reaches 1015ºC, at which temperature a 21 appears, indicating a dominance of double-height steps. After allowing the substrate to cool to the intended growth temperature for InSb, it is exposed to cracked Sb, resulting in the surface going from 21 to 11. This 11 reconstruction remains throughout the subsequent InSb deposition. InSb was deposited with a Sb/In flux ratio of about 5 and a growth rate of 0.2 nm/s. We have investigated growth temperatures between 300 and 420ºC for growth. To prevent the formation of the defects we introduced in some samples GaSb/AlSb supperlattice buffer layer. The best structural quality has been achieved at a growth temperature of 420ºC using GaSb/AlSb supperlattice buffer layer, resulting in our best electron mobility of 2.6104 cm2/Vs for a 2m film at room temperature. The samples grown at 420°C have the narrowest x-ray rocking curve width (FWHM of about 950 arcsec). Deep level noise spectra indicate the existence of the deep levels. The sample with the best crystal quality and highest mobility has the lowest traps. The deep levels have a temperature dependent behavior.

Thin InSb films on GaAs substrates by Molecular Beam Epitaxy

We optimized the suitable growth conditions for obtaining smooth surface and high-quality InSb epilayer grown on semi-insulating GaAs substrate. The low temperature (LT) buffer layer was introduced into the growth process to improve the surface morphology and interface quality of the epilayers. It was confirmed that high quality InSb epilayer strongly depends on LT InSb buffer layer and growth conditions and parameters. Our typical InSb samples were obtained at the growth temperature of 420–425 °C, with the optimum Sb/In ratio of 1.4:1, and in our experiments, the epilayer thickness was in the range of 1.0 to 2.2 µm. Typically, the room temperature X-ray diffraction (XRD) full width half maximum (FWHM) of 172'' and mobility of 64300 cm2 V-1 S-1 at 77 K were obtained for typical sample of 2.2 µm thickness.

Spin Dynamics in Narrow-Gap Semiconductor Epitaxial Layers

We report on investigation of the spin dynamics in InAs and InSb films grown on GaAs at a temperature range from 77 K to 290 K. For both materials, the large lattice mismatch with the GaAs substrate results in the formation of an interface accumulation layer with a large defect concentration, which strongly affects the spin relaxation in these areas. Moreover, the native surface defect in the InAs films resulted in an additional charge accumulation layer with high conductivity, but very short spin lifetime. In contrast, in InSb layers, the surface states introduce a depletion region. We have correlated the spin relaxation with a multi-layer analysis of the transport properties, and find that in a 1 μm thick InAs film, approximately 70% of the total current flows through the interface and surface accumulation layers, which have sub-picosecond lifetimes, whereas in InSb films of the same thickness, the semiconducting layer carries more than 90% of the total current, and the spin lifetime in the accumulation layer is only slightly less than that of the central semiconducting layer. We suggest that InSb could be a more attractive candidate for spintronic applications than InAs.

Influence of the annealing time on the structural properties for Flash evaporated InSb films

Indium Antimonide (InSb) thin films were grown onto well cleaned glass substrates at substrate temperatures (473 K) by flash evaporation. X-ray diffraction studies confirm the polycrystalline of the films and the films show preferential orientation along the (111) plane .The particle size increases with the increase of annealing time .The transmission spectra of prepared samples were found to be in the range (400-5000 cm-1 ) from FTIR study . This indicates that the crystallinity is improved in the films deposited at higher annealing time.

Advanced Heterostructure Si-InSb on Insulator Formed by Bonding of Hydrogen Transferred Si Layer and Implanted SiO2 Film

Using bulk silicon may be limited for 22 nm technological node due to silicon mobility limitation. New type of substrates needs for further scaling in CMOS microelectronics. We speculate that this new type of materials can be semiconductor heterostructure on insulator (HOI) compatible with current silicon planar CMOS technology. In this work an effect of interface mediated endotaxial (IME) growth of thin InSb film at Si/SiO2 bonded interface was experimentally observed and investigated for the first time. Joint semiconductor material stack obtained by hydrogen transfer of one layer material (silicon) and endotaxially grown second one (indium antimonide) placed initially into amorphous silicon dioxide film is presented. Thermodynamic, kinetic and lattice mismatch parameter influences on IME process are considered.

Nanoscaled Silicon Based Heterostructures Formed by Interface Mediated Endotaxy

New types of substrates are needed for further scaling in CMOS microelectronics. We speculate that this new type of materials can be semiconductor heterostructure on insulator (HOI) compatible with current silicon planar CMOS technology. In this work an effect of interface mediated endotaxial (IME) growth of thin InSb film at Si/SiO2 bonded interface was experimentally observed and investigated for the first time. Joint semiconductor material stack obtained by hydrogen transfer of one layer material (silicon) and endotaxially grown second one (indium antimonide) placed initially into amorphous silicon dioxide film is presented. Thermodynamic, kinetic and lattice mismatch parameter influences on IME process are considered.

Effect of AlSb buffer layer thickness on heteroepitaxial growth of InSb films on a Si(001) substrate

Aluminum antimonide (AlSb) layers with various thickness ranged from about 8 to 250 nm were grown at 520 °C as the buffer layer for the heteroepitaxial growth of InSb films on Si(001) substrates. InSb films were grown at 400 °C on the AlSb/Si(001), and were characterized by X-ray diffraction (XRD), atomic force microscope, as a function of the thickness of the AlSb layer. The XRD patterns of the InSb films grown on the AlSb layers show that even if the AlSb buffer layer, whose surface consists of many islands, is as thin as 8 nm, it is effective for the heteroepitaxial growth of InSb film on a Si(001) substrate, and the AlSb layer of about 40 nm is thick enough to grow heteroepitaxial InSb films on the Si(001) substrate. The results of the ϕ scan patterns of the films show that InSb films on a Si(001) substrate with AlSb buffer layer were heteroepitaxially grown without any rotation in the growth plane.

Spin lifetime in high quality InSb epitaxial layers grown on GaAs

The spin relaxation in undoped InSb films grown on GaAs has been investigated in the temperature range from 77to290K. Two distinct lifetime values have been extracted, 1 and 2.5ps, dependent on film thickness. Comparison of this data with a multilayer transport analysis of the films suggests that the longer time (∼2.5ps at 290K) is associated with the central intrinsic region of the film, while the shorter time (∼1ps) is related to the highly dislocated accumulation region at the film-substrate interface. Whereas previous work on InAs films grown on GaAs showed that the native surface defect resulted in an additional charge accumulation layer with high conductivity but very short spin lifetime, in InSb layers the surface states introduce a depletion region. We infer that InSb could be a more attractive candidate for spintronic applications than InAs.

Relaxation of photoinduced spins and carriers in ferromagnetic InMnSb films

The authors report time resolved measurements and control of photoinduced spin and carrier relaxations in InMnSb ferromagnetic films with 2% Mn content (grown by low-temperature molecular beam epitaxy) using femtosecond laser pulses, and compare them to analogous measurements on InBeSb and InSb films. In this work, magneto-optical Kerr effect and standard pump-probe techniques provided a direct measure of the photoexcited spin and carrier lifetimes, respectively. They observe decrease in relaxations times in the high laser fluence regime and an absence of temperature dependence of the relaxation times.

Study of annealing effects in In-Sb bilayer thin films

The thin films of In-Sb having different thicknesses of antimony keeping constant thickness of indium was deposited by thermal evaporation method on ITO coated conducting glass substrates at room temperature and a pressure of 10−5 torr. The samples were annealed for 1 h at 433 K at a pressure of 10−5 torr. The optical transmission spectra of as deposited and annealed films have been carried out at room temperature. The variation in optical band gap with thickness was also observed. Rutherford back scattering and X-ray diffraction analysis confirms mixing of bilayer system. The transverse I-V characteristic shows mixing effect after annealing at 433 K for 1 h. This study confirms mixing of bilayer structure of semiconductor thin films.

Heteroepitaxial growth of rotated InSb films on a Si(1 1 1) substrate via 2×2-In surface reconstruction

The heteroepitaxial growth of InSb films via In-induced surface reconstructions such as 2×2-In and √3×√3-In on a Si(1 1 1) substrate was carried out by using a two-step growth procedure in an ultra-high vacuum (UHV) chamber. The samples were characterized by high-energy electron diffraction (RHEED), X-ray diffraction (XRD), scanning tunneling microscopy (STM) and Hall measurements. The RHEED and XRD ( φ scan) patterns of the samples showed the existence of InSb crystals rotated by 30° with respect to Si substrate. From comparison between the growth of InSb films via 2×2-In and that via √3×√3-In, we found that the origin of the 30°-rotated InSb is due to the existence of the In–Sb bi-layer formed by 1 monolayer (ML) Sb deposition onto the In-induced surface reconstructions.

Low-temperature growth of InSb(1 1 1) on Si(1 1 1) substrate

Absract Low-temperature growth of InSb films on Si(1 1 1) substrate was performed in an ultra-high vacuum chamber by coevaporation of elemental Indium and Antimony. The grown InSb films were characterized by using X-ray diffraction (XRD) and atomic force microscopy (AFM). Despite large lattice mismatch of about 19.3% between them (1 1 1) preferentially oriented InSb films were obtained on Si(1 1 1) at the low growth temperature range of 200–300 °C. It is found that the high-quality InSb films with smooth surface and two kinds of domains grow on Si(1 1 1) substrate at the temperature rang of 220–240 °C.

Surface morphology of highly mismatched InSb films grown on GaAs substrates by molecular beam epitaxy

AbstractInSb films on GaAs(001) substrates with and without GaAs buffer layer have been grown by molecular beam epitaxy. Rather than surface undulations, aligned ripples and pyramidal hillocks along the orthogonal 〈110〉 directions were observed on the surface of InSb films. Both the preferential growth and the termination of ripples were proved to be related to strain‐driven mass transport. A model was proposed to elucidate the formation of the hillocks, which are more efficient to relax strain than ripples. Due to the strain relaxation through hillocks with small bases predominantly, the surfaces of the InSb films grown without a GaAs buffer layer are smoother than those of films grown with a GaAs buffer layer. (© 2007 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)

Planar Hall effect of indium antimonide thin film on silicon and nickel–zinc ferrite substrates

We have investigated Hall and planar Hall (PH) effect of indium antimonide (InSb) films thermally evaporated on two different substrates including Si and soft magnetic Ni–Zn ferrite. Polycrystalline InSb film with an average grain size of 1.2 μm shows substantial electron mobility of 6,700 cm2/Vs for Si and 5,680 cm2/Vs for Ni–Zn ferrite substrates respectively. Four-point bridge type Hall bar of InSb was fabricated using photolithography followed by chemical wet etch. An abrupt change in PH deviated from a normal PH curve was found on a ferrite substrate within a low field range of −50 to 50 Oe while no change happens on the Si substrate. Sharp PH curve immediately returns to the ordinary PH curve when applied field goes over −50 to 50 Oe without leaving any hysteresis of resistance. This is mainly attributed to the presence of the Bloch wall of Ni–Zn ferrite underneath InSb Hall bar. Intragranular domain wall movement is believed to be a prime source of the anomalous PH behavior in the low field range. The linear field dependence of PH in a resolution of 10 mΩ/Oe is sensitive high enough to be used as low-field magnetic sensors.

Oxide-free InSb (100) surfaces by molecular hydrogen cleaning

We report that annealing of an oxidized InSb (100) single-crystal sample at 250°C under molecular hydrogen flow [molecular hydrogen cleaning (MHC)] results in complete desorption of the surface oxides. Following this process, the surface morphology is found to be very smooth at the nanometric scale without any droplet structure and a nearly 1:1 In:Sb stoichiometry. MHC was applied to remove the native oxide of an epi-ready InSb(100) substrate used for molecular beam epitaxy growth of InSb films. These results suggest that MHC of InSb can be used as a very effective cleaning process for epitaxial film growth.

Heteroepitaxy of InSb films grown on a Si(0 0 1) substrate with AlSb buffer layer

The growth of InSb films on a Si(0 0 1) substrate with AlSb buffer layer was performed in an ultra high vacuum chamber (UHV) by a co-evaporation of elemental Indium (In) and antimony (Sb) sources. The samples were characterized by Auger electron spectroscopy (AES), X-ray diffraction (XRD) and atomic force microscopy (AFM). The surface morphology and the crystal quality of the grown films strongly depend on the flux ratio of Sb/In. It is found that the optimized flux ratio for the one-step growth procedure is about 2.9 to obtain the InSb films with smooth surface and good crystal quality, for the growth temperature of 300 °C. The two-step growth procedure was also used to further improve the crystal quality of the films.