Magnetron sputter epitaxy (MSE) of InSb on (100) GaAs and (100, 111) InSb for infrared detector applications

The growth of InSb-based compounds on GaAs, Si and InSb has received increased interest over the past few years due to the potential use for this material in integrated infrared imaging arrays. In this paper a new technique for the epitaxial growth of InSb is reported for the first time. The technique, based on the sputter deposition of InSb from solid InSb and Sb targets, magnetron sputter epitaxy (MSE), has been used to produce layers of relatively high structural and electrical quality and with excellent thickness uniformity and surface morphology. The electrical properties of p+/n diode test structures fabricated using these epilayers is presented.

Source:IOPscience

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In-situ XAFS studies on local structures of molten InSb compounds

The local structures of semiconductor InSb compound have been studied by in-situ XAFS in the temperature range of 300 and 823 K. Reverse Monte Carlo calculation is used to simultaneously fit both In and Sb K-edge EXAFS functions kχ(k) of InSb compound. The fitting results indicate that the average bond length R1 (2.80 Å) and the average coordination number N1 (4.0) of the first In-Sb (or Sb-In) shell of InSb (723 K) are similar to those (2.79 Å, 4.0) of crystalline InSb (300 K) with a zinc-blende structure, in spite of InSb compound possessing a large thermal disorder degree at 723 K. At the temperature of 828 K (Tm(InSb) = 798 K), the R1 and N1 of the first In-Sb shell are 2.90 Å and 5.8, and the R1 and N1 of the first Sb-In shell are 2.90 Å, and 5.5 for molten InSb, respectively. For molten InSb (828 K), the coordination numbers of the In-Sb (or Sb-In) first shell are mostly 5 and 6, and a few percent of In-In (or Sb-Sb) coordination appears in the first shell. It implies that the tetrahedron structures of the In-Sb (or Sb-In) covalent bonds of InSb compound have been destroyed in the liquid state.

Source:IOPscience

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Characterization of Al2O3/InSb/Si MOS diodes having various InSb thicknesses grown on Si(1 1 1) substrates

This paper discusses the capacitance–voltage (C–V) characteristics of Al2O3/InSb/Si (1 1 1) MOS diodes grown using MBE via InSb bi-layer with special care to the surface reconstruction. This growth technique is based on our finding that the InSb layer grown on a Si (1 1 1) substrate is rotated by 30° with respect to the substrate under certain initial conditions. This rotation drastically reduces the lattice mismatch from 19.3% to 3.3%, and improves the crystal quality of an InSb layer. To investigate the possibilities of InSb MOSFETs on Si substrates, we fabricated MOS diodes having an Al2O3 insulator film deposited by atomic layer deposition. C–V characteristics were measured both at RT and 77 K. It was found that the InSb grown on Si shows a degraded C–V curve compared to the InSb substrate, even though the mobility of the grown layer is quite high. We also investigated the effects of InSb thickness on the C–V characteristics of the MOSFETs. It was found that the quality of MOS diodes first degrades when decreasing the InSb thickness from 1 μm to 50 nm; further reduction of the InSb thickness improves it again. It was demonstrated that the MOS diode having a 10 nm InSb layer shows a good C–V curve, which is comparable to that of the InSb substrate. Finally, we discussed the possibility of the InSb/Si pseudomorphic MOSFETs.

Source:IOPscience

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Optical nonlinearity characteristics of crystalline InSb semiconductor thin films

The intensity-dependent nonlinear absorption and refraction characteristics of crystalline InSb thin films are investigated by z-scan method at 405 nm laser wavelength. Results show that the nonlinear absorption coefficient of crystalline InSb thin films is in the order of ~ + 10−2 m W−1, and the nonlinear refractive index is in the order of ~ + 10−9 m2 W−1. Variable-temperature ellipsometric spectroscopy measurements and electronic process analyses as well as theoretical calculations are employed to discuss the internal mechanisms responsible for the giant optical nonlinearity. Analysis results indicate that the nonlinear absorption mainly stems from the laser-induced free-carrier absorption effect, whereas the nonlinear refraction is mainly from thermal effect due to band gap shrinking and carrier effect due to the transition process of electrons, respectively. These characteristics may be responsible for the super-resolution effect in nano-optical information storage.

Source:IOPscience

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Growth and Characterization of InSb Thin Films on GaAs (001) without Any Buffer Layers by MBE

We report the growth of InSb layers directly on GaAs (001) substrates without any buffer layers by molecular beam epitaxy (MBE). Influences of growth temperature and V/III flux ratios on the crystal quality, the surface morphology and the electrical properties of InSb thin films are investigated. The InSb samples with room-temperature mobility of 44600 cm /Vs are grown under optimized growth conditions. The effect of defects in InSb epitaxial on the electrical properties is researched, and we infer that the formation of In vacancy (V ) and Sb anti-site (Sb  defects is the main reason for concentrations changing with growth temperature and Sb /In flux ratios. The mobility of the InSb sample as a function of temperature ranging from 90 K to 360 K is demonstrated and the dislocation scattering mechanism and phonon scattering mechanism are discussed.

Source:IOPscience

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