Study on Surface State Control Technique of InSb Material Ultraprecision Machining

Indium antimonide is one of the important materials which can be used to make semiconductor devices such as infrared detection device. Due to the low hardness and great brittleness, the surface scratching always appears and surface roughness is hard to lower during surface preparation. So it should be increasing the InSb surface quality during ultraprecision machining. In this paper the InSb surface adsorption-control technology was introduced. Through controlling surface roughness during chemical mechanical polishing(CMP) and using preferential adsorption during cleaning, the adsorptions of InSb surface were controlled. Through experiments, the CMP optimal process parameters under the alkaline conditions were gotten. Under such conditions, the preferable surface statewere realized. According to the preferential adsorption model, through using FA/O non-ionic surfactant the polished wafer surface can be kept in physical adsorption and easy cleaning state, so the wafer surface adsorption can be controlled effectively and the clean surface was obtained.

Source:IOPscience

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Optical design of a mid-wavelength infrared InSb nanowire photodetector

A periodic array of vertical InSb nanowires (nws) was designed for photodetectors in the mid-wavelength infrared (MWIR) region (λ = 3–5 μm). Simulations, using the finite element method, were implemented to optimize the nw array geometrical parameters (diameter (D), period (P), and length (L)) for high optical absorptance, which exceeded that of a thin film of equal thickness. Our results showed HE1n resonances in InSb nw arrays can be tuned by adjusting D and P, thus enabling multispectral absorption throughout the near infrared to MWIR region. Optical absorptance was investigated for a practical photodetector consisting of a vertical InSb nw array embedded in bisbenzocyclobutene (BCB) as a support layer for an ultrathin Ni contact layer. Polarization sensitivity of the photodetector is examined.

Source:IOPscience

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Interaction of Mn with GaAs and InSb: incorporation, surface reconstruction and nano-cluster formation

The deposition of Mn on to reconstructed InSb and GaAs surfaces, without coincident As or Sb flux, has been studied by reflection high energy electron diffraction, atomic force microscopy and scanning tunnelling microscopy. On both Ga- and As-terminated GaAs(0 0 1), (2 × n) Mn-induced reconstruction domains arise with n = 2 for the most well ordered reconstructions. On the Ga-terminated (4 × 6), the Mn-induced (2 × 2) persists up to around 0.5 ML Mn followed by Mn nano-cluster formation. For deposition on initially β2(2 × 4)-reconstructed GaAs(0 0 1), the characteristic trench structure of the reconstruction is partially preserved even beyond 1 monolayer Mn coverage. On both the β2(2 × 4) and c(4 × 4) surfaces, MnAs-like nano-clusters form alongside the reconstruction changes. In contrast, there are no new Mn-induced surface reconstructions on InSb. Instead, the Sb-terminated surfaces of InSb (0 0 1), (1 1 1)A and (1 1 1)B revert to reconstructions characteristic of clean In-rich surfaces after well defined coverages of Mn proportional to the Sb content of the starting reconstruction. These surfaces are decorated with self-assembled MnSb nanoclusters. These results are discussed in terms of basic thermodynamic quantities and the generalized electron counting rule.

Source:IOPscience

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Copper phthalocyanine molecules on an InSb(001) c(8 × 2) surface studied by ultra-high-vacuum STM and non-contact AFM

The surface ordering of copper phthalocyanine (CuPc) molecules deposited onto an InSb(001) c(8 ×2) reconstructed surface has been studied using scanning tunneling microscopy (STM), non-contact atomic force microscopy (nc-AFM) and low-energy electron diffraction (LEED). It was found that at room temperature the CuPc molecules are only weakly bound to the InSb surface and the adjacent molecules and consequently they are relatively mobile at submonolayer coverage. STM images show that at the initial stages of growth molecules are assembled in ordered molecular chains parallel to the surface reconstruction rows, i.e. along the [110] crystallographic direction. Furthermore, adsorption of the molecules at step edges is observed. At coverages below 1 ML molecules diffuse at the surface and form two-dimensional islands, which leads to an additional characteristic (n × 3) LEED pattern indicating one-dimensional ordering within the molecular chains. High-resolution STM imaging at negative sample bias reveals a unique structure of the molecular contrast which may be related to the highest occupied molecular orbital (HOMO) of the individual CuPc molecules. For CuPc monolayer coverage submolecular resolution is also obtained for nc-AFM imaging. Finally, examples of single molecule manipulation by the STM tip are given.

Source:IOPscience

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