The diameter of the spot of the laser beam was 3 mm, and point-to-multipoint method was used for irradiation of the samples. All experiments of nanocone formation were performed in ambient atmosphere at pressure of 1 atm, T = 20°C, GSK2126458 molecular weight and 60% humidity. Current–voltage (I-V) characteristics were measured for the nonirradiated and irradiated samples with nanocones formed on a surface of i-Ge samples. The measurements of the I-V characteristics were performed by soldering 99% tin and 1% antimony alloy contacts directly on the irradiated surface of Ge with the tin contacts on the opposite side. Measurements

of I-V characteristics were done at room temperature and atmospheric pressure. The structure consisting of Ni catalyst with thicknesses d = 30 nm deposited on commercial Si(111) single crystals were used for formation of microcones. Pulsed Nd:YAG laser for treatment Ni/Si structure with following parameters was used: wavelength of λ = 1,064 nm, pulse duration of τ = 150 ms, pulse repetition rate of 12.5 Hz, power at P = 1.0 MW, laser intensity of I = 4 MW/cm2. The threshold intensity of microcones formation is 3.15 MW/cm2. The samples were treated by laser radiation in scanning mode with step of 20 μm. All experiments of microcones formation were performed in ambient atmosphere see more at pressure of 1 atm, T = 20°C, and 60% humidity. Investigations of the reflection obtained from the surface with decorated microcones

structure were done with Avantes AvaSpec-2048 UV/VIS/NIR spectrometer (Avantes Inc., Apeldoorn, The Netherlands) in the wavelength range of 200 to 1,100 nm [spectrometer based on selleck chemicals llc AvaBench-75 symmetrical Czerny-Turner construction (Avantes Inc., Apeldoorn, The Netherlands) with 2,048 pixel CCD detector and resolution of 1.4 nm]. Surface morphology and chemical analysis of the samples by scanning electron microscope (SEM) with integrated energy dispersive X-ray spectrometer (SEM-EDX) Hitachi S-900 (Hitachi America, Ltd., Brisbane, CA, USA) were used. Photoluminescence (PL) measurements

were performed by equipment Fluorolog-3, using photo detector Hamamatsu R928 and xenon lamp (450 W) (Hamamatsu Photonics GmbH, Herrsching, Germany). Results and discussion Nanocones Quantum confinement effect (QCE) is one of the most investigated phenomena in semiconductors. The presence of QCE in semiconductors leads to a crucial change of physical properties of much the material, especially in quantum dots. Recently, a new quantum system, quantum cone [9], which possesses unique properties, was observed. It is known that if the radius of the sphere inscribed in nanostructure is equal or less than Bohr’s radius of exciton, quantum confinement effect takes place [13]. The diameter of the nanocone is a function of its height d(z); therefore, a nanocone is a graded band gap structure. A schematic image of a nanocone with a gradually increasing band gap from a substrate up to the tip of the cone is shown in Figure 1a.