Li et al. Nanoscale Research Letters 2011, 6:601 http://www.nanoscalereslett.com/content/6/1/601 polycrystalline InSb target is used, the film is rich in Indium and the excess indium is presented on the sur- face of the film in the form of Indium balls. This has usually been explained by the relatively large equilibrium vapor pressure of group V metals in comparison with the group III metals. In this study with a purity of 99.95% antimony (Sb) and 99.995% of Indium (In), the InSb template was made by the water-cooled copper crucible in a vacuum arc furnace under Argon atmo- sphere. After confined, rod-like samples are suction- casted into Ф10 mm × 75 mm size. By using the wire cutting, the rod is cut into suitable shape specimens, cleaning with acetone, then is sealed into quartz tube under 10-4 Torr vacuum degree, keeping for 24 h at 450°C to achieve uniformity of composition, following the composition of each specimen was determined by energy spectrum technique. The In/Sb ratio of the films was also measured, and after measuring more than 30 films, it was known that the film with atom ratio of 1:1 was grown by the target with the ratio of 1:0.82. Post-deposition thermal annealing of film was accom- plished in N2 atmosphere using rapid photothermal annealing system (RTA). The samples were annealed at 400°C for 2 min. The typical ramp-up and ramp-down temperature was approximately 25°C/s. The accuracy of temperature measurement was ± 2°C. X-ray diffraction (XRD), transmission electron micro- scopy (TEM), and scanning electron microscopy (SEM) were used to study the crystallographic microstructure, the film thickness, and the surface morphology of the film, respectively. The powder XRD pattern was recorded on Philip X’Pert Discover (Cu Ka radiation, l = 1.5406 Å), the scanning range is from 10° to 70°. Cross-sectional TEM image was recorded on JEOL JEM 2010F field emission electron microscope, using an accelerating voltage of 200 kV. The plan-scan images were taken on FEI Quanta 200 scanning electron microscope. Fourier Transform infrared spectroscopy (FTIR) mea- surement was carried out by Perkin Elmer Lamda 2000 spectrum in absorption mode at room temperature in the spectral range between 2.5 and 25 μm, and the SiO2/Si wafer was used as the reference. The I-V characteristics were recorded using a Keithley 6517A electrometer fitted with a voltage source. The field-effect phenomena were investigated on the XOI heterostructure. Results and discussion XRD patterns of both as-deposited InSb films and after RTA treatment at 400°C are shown in Figure 1. The XRD spectra show that the as-deposited InSb film is characterized by two humps indicating an amorphous structure in Figure 1a. After the film was annealed, Page 2 of 4 Figure 1 X-ray patterns of InSb films: (a) as-deposited and (b) RTA-annealed. three broad InSb diffraction peaks were observed, which were assigned to be (111), (220), and (311) orientations of InSb with a zinc-blend structure in Figure 1b. The full width at half maximum (FWHM) of each XRD peak was carefully measured, and the nanocrystals size was calculated by Scherr formula [13] D = 0.9λ/B cos θ (1) where l is the wavelength of the X-ray radiation (l = 0.154 nm), B is FWHM of the peak (in radians) cor- rected for instrumental broadening, θ is Bragg angle, and D is the crystallite size. The InSb NCs size was cal- culated by this formula and the result is 12.3 nm. The InSb NCs’ ultrathin film is shown in Figure 2a, it can be seen that the film has a uniformly deposited sur- face, composed of tightly packed spherical grains. The grains’ size distribution was obtained and is shown in Figure 2b. The average grain size was found to be 14.6 nm. This value matches well with what we have obtained from the XRD measurements (12.3 nm). Good coverage and continuity of the film on the substrate indicates that the film could be used easily in various devices. A cross-sectional bright-field transmission elec- tron micrograph of InSb NCs film is shown in the inset of Figure 2a, the thickness of the deposited InSb layer is about 35 nm. Figure 3 shows that the measurement of infrared absorbance using FTIR in the wavelength range 2.5-25 μm. A sharp rise in absorbance is near 4.7 μm, which corresponds to the bandgap energy of the material (0.264). The typical bandgap energy for bulk InSb is 0.18 eV. Here, because of the quantum confinement effect exerted by the NC particles [14], a blue shift in the bandgap energy about 0.084 eV was observed. The