InSb Layers Research Articles

High-Quality InSb Growth on GaAs and Si by Low-Pressure Metalorganic Chemical Vapor Deposition

ABSTRACTWe report the first InSb film growth on Si by low-pressure metalorganic chemical vapor deposition. High-quality layers of InSb have been grown on Si and GaAs substrates. InSb films displayed mirror-like morphology on both substrates. X-ray full width at half maximum of 171 arcsec on GaAs and 361 arcsec on Si for a InSb layer thickness of 3.1 μm were measured. Room-temperature Hall mobilities of 67,000 and 48,000 cm2/V.s with carrier concentration of 1.5×1016 and 2.3×1016 cm−3 have been achieved for InSb films grown on GaAs and Si substrates, respectively. A 4.8 μ-thick InSb film on GaAs exhibited mobility of 76,200 cm2/Vs at 240 K.

Formula omitted] quantum well structures grown by molecular beam epitaxy

Molecular beam epitaxy was used to grow lattice mismatched In xGa 1−xSb layers on GaAs substrates. Optical and structural properties were examined by photoluminescence (PL) and transmission electron microscopy (TEM). Growth of the strained layers was found to be in layer-by-layer mode up to a critical layer thickness (CLT) where three dimensional growth and eventually dislocation generation occured. TEM revealed dislocations and stacking faults in a 2 monolayer thich In O.25Ga 0.75Sb layer while a 3 monolayer thick InSb layer was defect free. The PL experiments were in general accordance with the TEM data showing an increase of critical layer thickness with increasing In-mole fraction. A reduced PL-intensity for the GaSb quantum wells is discussed in terms of indirect bandgap transitions and a staggered band line up between GaAs and GaSb.

Infrared magneto-optical and photoluminescence studies of the electronic properties of In(As,Sb) strained-layer superlattices.

Long-wavelength magnetotransmission and photoluminescence measurements were performed on InAs{sub 0.13}Sb{sub 0.87}/InSb strained-layer superlattices (SLS's). The energies and reduced effective masses of several interband optical transitions were obtained from these experiments. SLS's with different layer thicknesses produced self-consistent results. With these data, the type-II band offset and band-edge strain-shift parameters were accurately determined. Consistent with a type-II offset, an extremely small, in-plane effective-mass hole ground state was observed, thus proving that the hole quantum well is located in the biaxially compressed, InSb layer. Nonparabolicity, suggesting valence-band anticrossing, was also observed.

Use of atomic layer epitaxy buffer for the growth of InSb on GaAs by molecular beam epitaxy

A 300 Å buffer layer of InSb grown by atomic layer epitaxy at a substrate temperature of 300 °C at the GaAs/InSb interface has been employed to grow epitaxial films of InSb having bulk-like properties. The reduction of the defects in the top InSb film has been observed with cross-sectional transmission electron microscopy and channeling Rutherford backscattering spectroscopy. The optimum substrate temperature for the primary InSb layer growth was 420 °C with an atomic flux ratio of Sb to In of 1.4 and a growth rate of 1 μm/h. The best 5-μm-thick InSb layers had x-ray rocking curve widths of 100 s, 77 K n-type carrier concentrations in the low 1015/cm3 range, and 77 K carrier mobilities greater than 105 cm2/V s. Mesa isolated photodiodes had carrier lifetimes of 20 ns, in comparison to 200 ns observed in bulk InSb having a similar carrier concentration. An unexplained, weak free-electron spin resonance transition has been observed in these films.

Be, S, Si, and Ne ion implantation in InSb grown on GaAs

Single- and multiple-energy Be, S, Si, and Ne ion implantations were performed at room temperature in InSb grown on semi-insulating GaAs substrates. The implanted material was subjected to both isochronal and isothermal annealing schemes. The as-implanted and annealed material was characterized by Hall, secondary ion mass spectrometry, and x-ray rocking curve measurements. The as-implanted material is highly n-type for all implant species used in this study. A maximum p-type activation of 90% and n-type activation of 16% was achieved for Be and S implants, respectively. Be activation depends on the thickness of the InSb layer. No in-diffusion of Be and S was observed even after 500 °C anneal. The Si implant has an amphoteric doping behavior.

Growth of InSb on GaAs by metalorganic chemical vapor deposition

High quality InSb epitaxial layers were grown on GaAs substrates by metalorganic chemical vapor deposition using a two-temperature growth procedure. Trimethylindium and triethyl- or trimethylantimony were used for the growth of InSb on GaAs. Transmission electron microscopy revealed the existence of a large number of misfit dislocations at the substrate-epitaxial layer interface and, in some samples, misoriented grains. The quality of the layers improved with thickness as indicated by transmission electron microscopy, X-ray rocking curve widths and Hall mobilities. The mobilities were correlated with surface roughness, X-ray rocking curve width and the Sb/In ratio. Hall mobilities up to 60,900 and 27,900 cm2/V·s were obtained at 300 and 77 K, respectively, on a 2.9 μm thick InSb layer.

Epitaxial growth of InSb on sapphire by rf sputtering

InSb films have been deposited directly by rf sputtering on sapphire substrates. X-ray diffraction and scanning electron microscopy data are presented to show that the InSb layer on sapphire (0001) is epitaxial and grows with (111) parallel to the substrate surface. Optical absorption studies of the epitaxial film also reveal distinct spectral features which resemble these from bulk, single-crystal InSb.

Epitaxial growth studies of InSb on CdTe: Kinetic and thermodynamic aspects of InSb/CdTe interface formation

We report studies of the interface formed when InSb is deposited onto a CdTe substrate in a molecular beam epitaxy chamber and elucidate conditions under which epitaxial growth is possible. We find that a necessary condition for epitaxy at a substrate temperature Ts is that the growth rate exceed a minimum value Ω min (T s ). Reflection high energy electron diffraction patterns taken in situ and transmission electron micrographs taken ex situ show that interfaces formed when Ω > Ω min have a short period roughness which is independent of the Sb/In flux ratio and which diminishes with increasing Ω. Raman spectra show no evidence of interfacial compounds. An analysis of Auger spectra of thin layers of InSb grown on CdTe indicates the existence of Te at the surface of the InSb but not in the layer itself. The Te concentration is found to decrease with InSb layer thickness. We propose a model based on a competition between the reaction of free In and Sb with the CdTe surface and the nucleation and growth of InSb. We use this model to account for the existence of Omin, interface roughness, and the presence of Te at the surface of the InSb epilayer.

A TEM investigation of the initial stages of InSb growth on GaAs (001) by molecular beam epitaxy

Abstract This investigation focuses attention on the very early stages of MBE growth of InSb on GaAs (001). Both conventional and high resolution TEM have been used to study InSb layers varying between 5 and 300 monolayers in average thickness. The observations provide conclusive evidence of three-dimensional nucleation and island growth. Complete lattice relaxation is brought about by a network of 1 2 ⪡110⪢ Lomer dislocations at the InSb/GaAs interface and there is strong evidence for the presence of an additional sphalerite interfacial phase. Threading dislocations and planar defects in the InSb epilayer are mainly introduced during island coalescence.

Epitaxial growth of InSb on GaAs by metalorganic chemical vapor deposition {au}R. M. ,Biefeld and

InSb epitaxial layers have been grown on GaAs substrates by metalorganic chemical vapor deposition using trimethylindium and triethyl- or trimethylantimony as sources of In and Sb. Transmission electron microscopy revealed the existence of a large number of misfit dislocations at the substrate-epitaxial layer interface and, in some samples, misoriented grains. The quality of the layers improved with thickness as indicated by transmission electron microscopy, x-ray rocking curve widths, and Hall mobilities. The mobility was correlated with surface roughness, x-ray rocking curve width, and the Sb/In ratio. Hall mobilities up to 60 900 and 27 000 cm2/V s were obtained at 300 and 77 K, respectively, on a 2.9-μm-thick epitaxial InSb layer grown using a two-step growth procedure.

Growth and characterization of In1−xGaxSb by metalorganic magnetron sputtering

The growth and optical band gaps of heteroepitaxial layers of the ternary In1−xGaxSb [0≤x≤1] on (100)GaAs is reported. The epilayers, prepared by metalorganic magnetron sputtering using trimethyindium, trimethylgallium, and a sputtered antimony beam, showed good structural and surface morphologies despite a lattice mismatch between substrate and epilayer of 9%–14%. Secondary ion mass spectrometry analysis indicated a background carbon level in proportion to the gallium concentration. The high levels of carbon were not present in the InSb layers prepared using TMI. All films showed optical absorptions characteristic of direct gap semiconductors. The bowing parameter for the system is somewhat lower than that observed for the corresponding bulk material and may be related to compressive stress in the layers.

Growth and characterisation of InSb/GaAs grown using molecular beam epitaxy

InSb films having 77 K mobilities above 100000 cm2 V-1 s-1, 77 K carrier concentrations less than 5*1015 cm-3 and X-ray rocking curve widths of 100 arcsec have been grown on GaAs using molecular beam epitaxy (MBE). A thin (300 AA) InSb layer was grown at 300 degrees C using an atomic layer epitaxy (ALE) technique prior to the main InSb growth to reduce defects. Transmission electron microscopy, Nomarski microscopy, X-ray rocking curve widths and channelling Rutherford-backscattering measurements all confirmed the improved quality of these films. The influence of other growth parameters such as substrate temperature, ALE layer thickness and Sb over-pressure on the film properties is discussed. Electron cyclotron resonance (ECR) has been used to characterise the InSb films. Collectively, the results show that the best InSb epilayers have properties approaching bulk InSb.

A transmission electron microscopy and reflection high-energy electron diffraction study of the initial stages of the heteroepitaxial growth of InSb on GaAs (001) by molecular beam epitaxy

I n situ reflection high-energy electron diffraction and cross-sectional and plan-view transmission electron microscopy have been used to investigate the initial stages of InSb growth on GaAs(001), by molecular-beam epitaxy. Growth of the InSb commences with the formation of rectangular-based islands, having flat tops and sloping sides, with facets on certain planes of types {111} and {113}. The islands show near normal lattice spacings, with no significant straining. As deposition proceeds, islands coalesce and, after the equivalent of 40 monolayers of deposition, form a connected network. Complete coverage of the GaAs substrate is achieved after ≂300 monolayers of deposition. This places a lower limit on the thickness of InSb layers, which may be considered in the design of optoelectronic devices.

Molecular Beam Epitaxial Growth and Characterization of InSb and InAsxSb1−x

ABSTRACTLayers of InSb and InAsxSb1-x were grown on GaAs and GaAs on Si substrates and then characterized by X-ray diffraction (XRD) and transmission electron microscopy (TEM) to determine the epilayer quality. Hall-effect measurements and photoluminescence (PL) were also performed. Single-crystal XRD indicated that the 5-μm InSb layers grown on GaAs had a peak full width at half maximum (FWHM) of 120 arc sec for the (004) reflection. Planar TEM of a 7-μm-thick InSb layer on GaAs(001) indicated a dislocation density of 2 x 106 cm−2 at the top of the layer. Hall effect measurements of an undoped 3.5-μm-thick InSb on semi-insulating GaAs indicated an electron density of 3.7 x 1016 cm−3 at 300K and a mobility of 45,000 cm2 / V-sec. At 77K these values were 2.7 x 1016 cm−3 and 49,200 cm2 / V-sec, respectively. The composition of the InAsxSb1-x was a function of the growth temperature and the As2/In ratio for both Sb2 and Sb4. The XRD (004) peak FWHM increased with the x value, indicating a deterioration in material quality. This may be caused by alloy segregation in InAsxSb1-x. The peak FWHM rapidly increases from x=0.1 to x=0.3 and then its value drops, indicating that the quality of the layers improved. InSb layers displayed a strong PL whereas the PL for the InAs0.5Sb0.5 layers was very weak. We also grew InSb and InAsxSb1-x layers on GaAs on Si. Optical transmission measurements on InSb indicated that the layers were under tensile stress. We believe this tensile stress could be used to lower the bandgap of InAsxSb1-x layers to provide longer cut-off wavelengths for infrared detectors.

Low Temperature p- and n- Type Doping of InSb Grown on GaAs Using Molecular Beam Epitaxy.

ABSTRACT30 nm thick layers of Be-doped InSb were grown by MBE, sandwiched between undoped layers of InSb on semi-insulating GaAs substrates. Using secondary ion mass spectroscopy (SIMS), it has been demonstrated that the p-type dopant, Be, undergoes an anomalous migration towards the top surface for substrate growth temperatures in excess of 340°C. A thermal diffusion process can be eliminated as an explanation since there was not an associated diffusion towards the substrate. At a substrate growth temperature of 340°C, the Be-doped layer had backside and frontside doping concentration gradients of 0.067 and 0.147 decade/nm. respectively. A sample grown at 420°C had a comparable backside doping concentration gradient, but the frontside gradient was essentially zero, i. e., uniform doping tothe surface. Electrical activation of the Be dopant, when grown at 340°C, compared to activation in GaAs grown at 580°C. was 38% and 47% for growth rates of 1.0 and 0.5 μm/h. While the Si dopant does not undergo a migration comparable to that of Be, it has been demonstrated that n-type doping of InSb with Si must be done at growth temperatures less than or equal to 340°C to obtain high carrier concentrations. The maximum n-type carrier concentration obtained was 6.2x1018/cm3, for a 0.5 μm/h growth rate at 340°C.

The growth of high-purity homoepitaxial InSb layers in a molecular-beam epitaxy reactor previously used for CdTe growth

Cross contamination problems can, in certain circumstances, impose a serious limitation for a molecular‐beam epitaxy (MBE) system that is utilized to perform the growth of different high‐purity semiconductors. Due to the very high capital cost associated with MBE technology it is essential that cross contamination be eliminated to allow continued use of the apparatus. In this paper we provide full details of a major vacuum‐system cleaning exercise performed on an MBE reactor, previously used for cadmium telluride growth, which has allowed it to be subsequently and successfully used for the growth of state of the art high‐purity InSb epilayers. Secondary ion mass spectroscopy (SIMS) and electrical measurements performed on InSb layers grown prior to the full cleaning process showed them to be heavily contaminated with tellurium. However, corresponding data obtained following the decontamination exercise indicated the successful removal of the previously observed impurities to below the SIMS detection limit. The cleaning process described should be suitable for any laboratory requiring to change the usage of an existing MBE reactor to the growth of alternative materials.

Spectroscopic study of metal/semimetal and metal/semiconductor interfaces

We have studied the interface formation between Al and Sb(111), In and Sb(111) as well as between Al and InSb(110). The analysis techniques are Auger electron spectroscopy, X-ray photoemission, low-energy electron diffraction and high-resolution electron energy loss spectroscopy. The main result is the formation of an ordered layer of AlSb or InSb if the Al or the In is deposited onto Sb(111) at 600 K. For the Al/InSb(110) interface, an exchange reaction between Al and In is observed. Al and In clusters are formed at the surface, and the concentration of these clusters is determined.

Ion Implantation in InSb Grown on GaAs

ABSTRACTBe, S, Si, and Ne implantations were performed at room temperature into InSb layers grown on undoped semi-insulating GaAs substrates. The implant damage in InSb is of ntype behavior. The implanted material was subjected to both isochronal and isothermal annealing schemes using a molybdenum strip heater. A maximum p-type activation of 90 % and si-type activation of 16 % was achieved for Be and S implants, respectively. Si implant has an amphoteric doping behavior.

Energy relaxation of light holes in InAs .15Sb .85/InSb multiple quantum wells

The energy relaxation rate of light in-plane holes in InAs .15Sb .85/InSb quantum wells has been measured using a Shubnikov-de Haas technique. In this Type II system, the holes reside in the InSb layers; strain reverses the heavy-light hole ordering and thus light holes are the charge carriers. The samples consist of 20 to 100 InAs .15Sb .85/InSb periods 100Å/200Å thick. The InAsSb barriers are doped with Be. The total carrier concentration p ≈ 1×10 11 cm −2 is obtained from Hall data. Shubnikov-de Haas oscillation amplitudes are measured and used to determine the light hole temperature for a given applied power. The steady state power per carrier is equated to the energy relaxation rate to determine the carrier temperature T H. The measured rate for low electric fields is proportional to T H n -T L n with n ≈ 3.2 and 2.5 for two different samples. These data are compared with theory and experiment for light holes in InGaAs/GaAs quantum wells.

Long-term relaxation of parameters of surface layers of III?V compounds

We report the results of an experimental study of the long-term relaxation (LTR) of the electrophysical parameters of surface layers of InSb and InAs and the lattice constant after the action of a pulse of electric field. The results are explained on the basis of the assumption that the parameters of a surface layer undergo long-term relaxation as a result of its electrostimulated structural rearrangement.