Optical investigation and application of copper selenide nanowires

Abstract

Growth and optical properties of copper selenide nanowires (nws) in alumina template were studied and discussed in respect to their application as films doped with semiconductor nanocrystals that provide promising optical properties. The results obtained indicate that nanoscaled copper selenide structures uniformly embedded at the bottom of alumina less than a micron in depth could be useful for mode locking in picosecond YAG type lasers. The operating wavelength of the material was identified by optical characterization. Copper selenide nanowires were examined as saturable absorber to yield passive wave mode-locking in a Nd 3+ / YAG laser (λ = 1.064 µm). Both the deposition conditions and subsequent annealing define the stoichiometry of copper selenides providing a slight shift of absorption spectra. One of the preponderant modern sciences nowadays is nanotechnology. While studying new semiconductor nanomaterials, great interest arrived for copper selenide nanoparticles [1][2][3][4][5][6][7][8][9]. One of their promising applications is optical switching devices, because of the transient bleaching effect [7][8][9]. Size, chemical composition, and crystalline structure of nanoparticles determine the character of light absorption processessame as for indirect p-type semiconductor, copper selenide Cu x Se y . Under ambient conditions the material exists as a series of stable and metastable phases, with the stoichiometry coefficients x and y varying from 1 to 3. Variation in stoichiometry results in change of crystalline structure, absorption spectra, and both direct and indirect band gap E g,dir , E g,indir values [10]. Moreover, the crystalline structure and phase composition of copper selenide leads to different optical and other properties obtainable by annealing of specimens.In recent years, a number of researchers have explored semiconductor nanocrystals as saturable absorbers to create passive mode-locked solid-state lasers [7][8][9]. Nanostructured copper selenide appears to gain shallow absorption centres characterized by the absorp- * The report presented at the 37th Lithuanian National Physics Conference, 11-13 June 2007, Vilnius, Lithuania.tion peak in near-IR, which leads to optical nonlinearity effects [10]. The observed absorption range appears to be consistent with the first harmonic of YAG type solid state laser (wavelength within 1-1.5 µm). We studied here for the first time the nonlinear optical properties and mode-locking performance of porous alumina thin films containing copper selenide. Thus, arrays of nanoscaled Cu 3 Se 2 (umangite) before and after annealing at several different temperatures were fabricated and investigated.Aluminium foil of 100 µm in thickness and 99.995 at% purity from Goodfellow was used to prepare samples of 12 × 12.5 mm 2 in dimensions. Before anodizing, the surface of samples was cleaned by degreasing in acetone, etching in a hot 1.5 M NaOH solution for 20 s, desmutting in 10% HNO 3 , thoroughly rinsing, and drying in nitrogen stream. The growth of porous aluminium ox...

Formation of Copper Selenide synthesized by Mechanical Alloying

“…In any case, the applied annealing conditions, lead to the formation of the orthorhombic crystal structure Cu 2 Se x and the cubic crystal structure Cu 1.8 Se. This result is in agreement with a previous study by R. Subas et al, at which no substantial improvement of the crystal structure was found at such high temperatures [26]. It is important to investigate lower annealing temperatures, around 300 °C, in order to achieve a higher contribution of β-phase Cu 2 Se to the final material.…”

“…Typically, annealing, in addition to improving the crystallinity of a material, [25] can be used to obtain different regions of the phase diagram. In particular, β-phase Cu 2 Se can be attained by using rapid cooling after annealing under appropriate conditions [26]. Previous studies have identified the use of annealing in pure or doped Cu-Se system to provide the Cu 2 Se cubic crystal structure i.e.…”

Transient absorption of copper selenide nanowires of different stoichiometry

“…It is obvious from the steady-state absorption spectra that variations of the electrodeposition parameters and post-deposition treatment result in distinct optical properties of each sample. It was demonstrated that the peak intensity of the absorption band related to the middle-gap states depends on the degree of the sample oxidation [20] and its energetic position can be tuned within the spectral range of 0.8-1.25 eV [14,21]. The sample annealing causes the most notable post-formation treatment effects.…”

“…Copper selenide is a precursor material of CuInSe 2 , used for highly efficient photovoltaic elements [5,12]. Attempts of application of copper selenide for optical filters [13], saturable absorbers for a passive mode locking of near-IR solid-state lasers [14], humidity sensors [15], highly effective hole injection layers for use with p-type organic semiconductors [3], novel nanotubes [16] have also been recently reported.…”

Síntesis Y Caracterización De Nanoestructuras Tipo Cobre-Selenio Obtenidas Mediante Las Técnicas De Microondas Y Mecanosíntesis

“…En los últimos años las nanoestructuras de seleniuro de cobre han tenido un alto interés dado que el seleniuro de cobre posee propiedades fascinantes y por ello amplias aplicaciones en campo tecnológico como: convertidores termoeléctricos 1 , filtros ópticos 2 , dispositivos fotoelectrónicos de alta eficiencia 3 , superconductores iónicos 4 , sensores de gases 5 , células solares 6 y fotocatalizadores 7 que permiten degradar productos químicos peligrosos. Es por eso que se vienen utilizando e implementando métodos para su síntesis como el solvotermal 8 , irradiación gamma 9 , sonoquímico 10 , electrodeposición 11 , evaporación al vacío 12 , coloidal 13 , deposición de baño químico 14 , deposición química de vapor 15 y deposición por láser pulsado 16 .…”