Bo Ling

Room Temperature Excitonic Whispering Gallery Mode Lasing from High‐Quality Hexagonal ZnO Microdisks

O N In recent years, low-dimensional semiconductor structures have attracted extensive research interest because of their fundamental importance and wide range of potential applications in nanotechnology. Notable achievements have been witnessed by light-emitting devices, lasers, and solar cells based on group IV elements (Si and Ge), [ 1 ] and group III–V (GaN and GaAs), [ 2 ] and II–VI compound semiconductors (ZnO, ZnS, and CdSe). [ 3–6 ]

Ultraviolet emission from a ZnO rod homojunction light-emitting diode

Ultraviolet electroluminescence was demonstrated at room temperature from a ZnO rod homojunction light-emitting diode array. The p-type doping was realized by phosphorous (P) ion implantation into defect-free ZnO rods followed by annealing. High resolution transmission electron microscopy shows the lattice compression of annealed single crystalline P-doped ZnO rod compared to the as-grown ZnO rod, suggesting atomically incorporation of P into the ZnO wurtzite structure. p-type doping was confirmed by low temperature photoluminescence spectra and single rod current-voltage characterization.

Color tunable light-emitting diodes based on p+-Si/p-CuAlO2 /n-ZnO nanorod array heterojunctions

Wide-range color tuning from red to blue was achieved in phosphor-free p+-Si/p-CuAlO2/n-ZnO nanorod light-emitting diodes at room temperature. CuAlO2 films were deposited on p+-Si substrates by sputtering followed by annealing. ZnO nanorods were further grown on the annealed p+-Si/p-CuAlO2 substrates by vapor phase transport. The color of the p-CuAlO2/n-ZnO nanorod array heterojunction electroluminescence depended on the annealing temperature of the CuAlO2 film. With the increase of the annealing temperature from 900 to 1050 °C, the emission showed a blueshift under the same forward bias. The origin of the blueshift is related to the amount of Cu concentration diffused into ZnO.

Electroluminescence From Ferromagnetic Fe-Doped ZnO Nanorod Arrays on p-Si

Vertically aligned Fe-doped ZnO nanorod arrays (ZnO:Fe NRAs) with weak ferromagnetism at room temperature (RT) have been fabricated by in situ doping of Fe into ZnO nanorods (NRs) using a simple thermal chemical vapor deposition method. Structure analyses indicated that the NRs have a single-crystalline wurtzite structure without any detectable segregated cluster or impurity phase. Both photoluminescence and electroluminescence (EL) showed near-band-edge and broad defect-band emissions at RT. The EL from ZnO:Fe NRAs/p-Si light-emitting diodes red shifted with increasing current injections, which was ascribed to the doping effect of the Fe.

Low-Temperature Facile Synthesis of ZnO Rod Arrays and Their Device Applications

Different morphologies of ZnO rod arrays with tunable photoluminescence (PL) were synthesized by vapor-phase transport deposition. The morphology and luminescence properties of ZnO rod arrays were found to be dependent on the deposition temperature and can be further tuned by postgrowth annealing treatment. Crystalline ZnO rods with intense UV emission at room temperature (RT) can be synthesized under a relatively lower temperature of 500 °C in a conventional tube furnace. ZnO rods grown at higher or lower temperature regions, however, showed additional defect-related emissions. Besides the commonly observed green emission from vapor-deposited ZnO rods, our samples also showed broad orange-red emission centered at ca. 620 nm. The origin of the different emission bands from the ZnO rod arrays was analyzed based on the annealing treatment in conjunction with the PL characterizations. Furthermore, two prototypes of optoelectronic devices (i.e., LEDs and FETs) were fabricated based on the as-grown ZnO rods. UV electroluminescence was achieved from ZnO rod arrays/p+-Si heterojunctions at RT, and FET based a single ZnO rod showed comparable transistor properties with previous reports on the ZnO nanorods grown at higher temperatures.

Fabrication and characterization of n-ZnO nanorod/p-CuAlO 2 heterojunction

n-ZnO nanorod/p-CuAlO2 heterojunction diodes have been fabricated on p+-Si (100) substrates. The p-CuAlO2 thin films were deposited on Si substrates by DC-sputtering method and then n-ZnO nanorods were grown by vapor phase transport (VPT) system on the CuAlO2 layer. The well aligned ZnO nanorods show single wurtzite hexagonal structure. Current-voltage characterization of the heterojunction exhibits rectifying diode behavior with a turn-on voltage of about 4.5 V. Electroluminescence emission, involving a weak near-band-edge emission of ZnO at 380 nm and a strong deep-level emission at 550 nm were observed at room temperature from the diode under forward bias.

Nanorod‐form ZnO‐homojunction ultraviolet light‐emitting diodes

— Ultraviolet (UV) light-emitting diodes based on ZnO-homojunction nanorods is reported. p-type doping can be obtained from intrinsic (or close to) ZnO by introducing acceptors, such as P or As, using ion implantation followed by appropriate thermal annealing and dopant activation. Our approach provides a possible solution to p-type doping of ZnO and ZnO-homojunction light-emitting diodes. It is interesting to note that this solution is offered in the form of nanorods.

Synthesis and electrical characteristic of P-type ZnO film on indium-tin-oxide glass substrate by ultrasonic spray pyrolysis

This paper has present a transparent diode device fabricated by p and n type ZnO films using ultrasonic spray pyrolysis (USP) method. The ammonia is added to the solution to provide the N-source and the P type ZnO can be obtained. I-V curve for the transparent diode can be measured and the turn-on voltage of the diode device is 2.3V.