Growth of ZnO nanostructures on Si by means of plasma immersion ion implantation and deposition

Abstract

Crystalline zinc oxide (ZnO) nanostructures have been grown on Si substrates by means of Plasma Based Ion Implantation and Deposition (PIII&D) at temperature of about 300 0 C and in the presence of an argon glow discharge. In the process a crucible filled with small pieces of metallic zinc plays the role of the anode of the discharge itself, being polarized by positive DC voltage of about 400V. Electrons produced by thermionic emission by an oxide cathode (Ba, Sr, Ca)O impact this crucible, causing its heating and vaporization of Zn. Partial ionization of Zn atoms takes place due to collisions with plasma particles. High negative voltage pulses (7 kv/40μs/250Hz) applied to the sample holder cause the implantation of metallic zinc into Si surface, while Zn deposition happens between pulses. After annealing at 700 0 C, strong UV and various visible photoluminescence bands are observed at room temperature, as well as the presence of ZnO nanoparticles. The coated surface was characterized in detail using X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), energy dispersive spectroscopy (EDS), scanning electron microscopy (SEM), atomic force microscopy (AFM) and photoluminescence (PL) spectroscopy. XRD indicated the presence of only ZnO peaks after annealing. The composition analysis by EDS revealed distinct Zn/O stoichiometry relation depending on the conditions of the process. AFM images showed the formation of columns in the nanoscale range. Topography viewed by SEM showed the formation of structures similar to cactus with nanothorns. Depth analysis performed by XPS indicated an increase of concentration of metallic Zn with increasing depth and the exclusive presence of ZnO for outer regions. PIII&D allowed to growing nanostructures of ZnO on Si without the need of a buffer layer.

Three-photon excitation of an upconversion random laser in ZnO-on-Si nanostructured films

“…nonlinear growth of the emitted intensity versus EPE. The laser action in the UV, centered at ≈390 nm, arises from bandto-band transition [30], as in one-photon-pumped RLs in ZnO reported before [22,23], or in the three-photon ZnO nanorod Fabry-Perot nanocavities demonstrated in [31]. The linewidth reduction in Fig.…”

“…The process of PIII&D was performed in a system called VAST (acronym for Vaporization of Solid Targets) [30]. In this system, an argon/oxygen glow discharge is first switched on at a pressure of 10 −3 mbar.…”

“…In this work, we describe RL emission by employing nanostructured films of ZnO prepared by the Plasma Immersion Ion Implantation and Deposition (PIII&D) method [30]. By using femtosecond pulses, three-photon-induced photoluminescence yielded UV (≈390 nm), blue (≈401 nm), and a broadband visible emission centered at ≈515 nm.…”

Thin films growth by PIIID technique from hexamethyldisilazane/argon mixture

“…Although applications of plasma polymerization are of growing technological importance, the processes that take place in the plasma are poorly understood. PIIID is a highly efficient technique for surface modification of metals, semiconductors, ceramics and polymeric materials and on this account, it has been employed in different areas, such as aeronautics, optics, biomedics, coatings and electronics [6][7][8][9][10][11][12][13][14][15][16]. In this implantation and deposition process, the substrates (or samples) are immersed in the plasma and are polarized with high voltage pulses.…”