Room-Temperature Lasing Observed from ZnO Nanocolumns Grown by Aqueous Solution Deposition

A fast sonochemical approach for the synthesis of solution processable ZnO rods

“…1͑a͒, a feature relevant to lasing applications of structured ZnO films. 1,11 The aspect ratio, length/width of the rods can be tuned by varying the molar concentration of the initial mixture. On average, from a 10 −2 M solution rods with a width of ca.…”

“…In a hydrothermal decomposition reaction, a 1:1 molar solution of zinc nitrate, Zn͑NO 3 ͒ 2 ·6H 2 O and hexamethylenetetramine ͑HMTA͒, ͑CH 2 ͒ 6 N 4 is placed in an oven at 90°C for 6 h. Consequently, hydroxide ions are formed by decomposition of HMTA and they react with Zn 2+ to form ZnO ͑CH 2 ͒ 6 N 4 + 6H 2 Normally, ZnO rods have hexagonal polar facets, 10 which are an important element for lasing applications of ZnO structures, as the polar facets at the extremities act as the mirrors of a Fabry-Pérot cavity, while a reduced lateral scattering is guaranteed by the high refractive index of the ZnO ͑n = 2.45͒, with the rod effectively acting as a waveguide. 1,11 An imperfect 1:1 molar ratio of the starting solution may result in an acicular shape of the rods. Previously, ultrasonication of a zinc nitrate and HMTA solution has been shown to accelerate the synthesis.…”

One-dimensional ZnO nanostructures: Solution growth and functional properties

“…Zn 2+ is known to coordinate in tetrahedral complexes. Due to the 3d 10 electron configuration, it is colorless and has zero crystal field stabilization energy. Depending on the given pH and temperature [55], Zn 2+ is able to exist in a series of intermediates, and ZnO can be formed by the dehydration of these intermediates.…”

“…Zn(OH) 2 dehydrates into ZnO when heated in an oven [84], in a microwave [88], under ultrasonication [89], or even under sunlight [90]. All five reactions (6) to (10) are actually in equilibrium and can be controlled by adjusting the reaction parameters, such as precursor concentration, growth temperature and growth time, pushing the reaction equilibrium forwards or backwards. In general, precursor concentration determines the nanowire density.…”

“…It has been demonstrated to have enormous applications in electronic, optoelectronic, electrochemical, and electromechanical devices [3][4][5][6][7][8], such as ultraviolet (UV) lasers [9,10], light-emitting diodes [11], field emission devices [12][13][14], high performance nanosensors [15][16][17], solar cells [18][19][20][21], piezoelectric nanogenerators [22][23][24], and nanopiezotronics [25][26][27]. One-dimensional (1D) ZnO nanostructures have been synthesized by a wide range of techniques, such as wet chemical methods [28][29][30], physical vapor deposition [31][32][33], metal-organic chemical vapor deposition (MOCVD) [34][35][36], molecular beam epitaxy (MBE) [37], pulsed laser deposition [38,39], sputtering [40], flux methods [41], eletrospinning [42][43][44], and even top-down approaches by etching [45].…”