Luminescence of ZnSe nanowires grown by metalorganic vapor phase deposition under different pressures

Abstract

Growth and luminescence of zinc-blende-structured ZnSe nanowires by metal-organic chemical vapor depositionQuasi-one-dimensional ZnSe nanowires have been synthesized by metalorganic chemical vapor deposition on Si ͑001͒ substrates, sputter coated with gold catalyst, at various pressures using diethylzinc and diisopropylselendie. The nanowires appear to be randomly oriented on the substrate and some are slightly bent along their length. X-ray diffraction and scanning electron microscopy studies show that the nanowires are zincblende in structure and have a uniform cross section along its length, and an average diameter about 30 nm, regardless of growth pressure. Individual strands of the nanowires were examined by high-resolution transmission electron microscopy and were found to be single crystals elongated along the ͗112͘ crystallographic direction. Gold particles at the tips of the nanowires identified by transmission electron microscopy and atomic force microscopy indicate that the nanowires grow via the vapor-liquid-solid process. Room-temperature photoluminescence spectra of the ZnSe nanowires grown under different pressures show variations in their optical properties, despite their similarity in morphology and crystalline structure. At the optimal pressure of growth, strong near band-edge emission and very weak deep-level emissions are observed, indicating the low level of nonstoichiometric defects in the resulting ZnSe nanowires.

Atomic chains of group-IV elements and III-V and II-VI binary compounds studied by a first-principles pseudopotential method

“…21,22 Although nanowires of metallic elements, 23 carbon nanotubes, 24 and atomic strings of carbon 22,[25][26][27][28] have been investigated extensively, studying similar forms of other group-IV elements ͑Si, Ge, Sn͒ and III-V ͑such as BN, AlP, GaAs, etc.͒ and II-VI ͑CdS, ZnSe, etc.͒ compounds are relatively recent. [29][30][31][32][33][34][35][36][37][38][39] These materials, which have covalent or polar semiconductor crystal forms in bulk, as well as quasi-two-dimensional and finite cross-section onedimensional ͑1D͒ geometries, 40,41 are used in important optoelectronic applications. Their string forms are expected to exhibit some useful properties to be exploited in future electronic devices.…”

Synthesis and Characterization of SiO2-Sheathed ZnSe Nanowires

“…The NBE emission is known to originate from bound excitons whereas the deep level emission is mainly attributed to deep levels such as vacancies, interstitials, and surface states. [23][24][25][26][27] The PL spectra of the SiO 2 -sheathed ZnSe nanowire samples annealed in O 2 and N 2 /3-mol % H 2 atmospheres are displayed in Figure 6 along with that of the as-synthesized one. The PL spectra of the as-synthesized nanowire samples were dominated by a broad deep levelrelated orange emission band centered at around 610 nm and the NBE emission was negligible.…”

“…The room temperature PL spectrum of ZnSe nanostructures is known to be typically dominated by two characteristic emission bands: [23][24][25][26][27][28] (1) a near-band edge (NBE) emission band centered at around 465 nm and (2) a broad deep level emission band in the wavelength range of 500-680 nm. The NBE emission is known to originate from bound excitons whereas the deep level emission is mainly attributed to deep levels such as vacancies, interstitials, and surface states.…”

Properties of a charge in the nanoheterosystems with quantum wells and barriers

“…Note that at the pole points of the Dirac δ-function the wave-function derivative changes stepwise [17]. In particular…”

“…In this way resonant diodes and quantum transistors used in novel nanoelectronic devices are made. Hence, in plenty of experimental as well as theoretical works, electron, hole,and exciton energy states are studied in composite quantum wires [10][11][12][13][17][18][19][20].…”