Wavelength-Tunable Ultraviolet Electroluminescence from Ga-Doped ZnO Microwires

Abstract

The usage of ZnO as active layers to fabricate hybrid heterojunction light-emitting diodes is expected to be an effective approach for ultraviolet light sources. Individual ZnO microwires with controlled gallium (Ga) incorporation (ZnO/Ga MWs) have been fabricated via a chemical vapor deposition method. It is found that with the increasing Ga-incorporated concentration, the near-band-edge (NBE) photoluminescence of the ZnO MWs blue-shifted gradually from 390 to 370 nm. Heterojunction diodes comprising single ZnO/Ga MWs and p-GaN have been fabricated. With increasing injection currents, the interfacial emissions can be suppressed effectively and the typical NBE emission dominates the electroluminescence (EL). In particular, with increasing Ga-doping concentration, the dominant EL emission wavelengths of the ZnO/Ga MW-based heterojunction diodes blue-shifted from 384 to 372 nm, and the blue shift can be ascribed to the Burstein-Moss effect induced by the Ga incorporation. The present work demonstrates the feasibility of optical band gap engineering of ZnO MWs and the potential application for wavelength-tuning ultraviolet light sources.

Hybrid quadrupole plasmon induced spectrally pure ultraviolet emission from a single AgNPs@ZnO:Ga microwire based heterojunction diode

“…On incorporation with residual O 2 in the furnace chamber, individual Gadoped ZnO MWs could be gradually formed around the Si substrate. 24,[38][39][40] A single ZnO:Ga MW was selected to construct an incandescent-type lamp lament source, with the emission region located towards the center of the wire. By incorporating Ag quasiparticle nanolms (the sputtering time: 300 s), a single Ag@ZnO:Ga MW based incandescent-type emitter was also fabricated.…”

“…Therefore, typical NBE emission with higher wavelength stability centered around 378.0 nm was realized by the single AgNPs@ZnO:Ga MW based heterojunction diode. 6,40,44,45 To investigate the NBE-type emission characteristics of the single AgNPs@ZnO:Ga MW based heterojunction diodes, a plot of the dominant emission peak wavelength versus the injection current is depicted in Fig. 1(g).…”

“…On further increasing the injection current beyond 5.0 mA, the m was estimated to be about 1.8, showing that radiative recombination generally made up the major part of the light emission for the light output. 40,46 Additionally, the spectral linewidth as a function of injection current was also taken into account. On increasing the injection current in the range from 0.03 to 8.0 mA, Fig.…”

“…The preparation of individual AgNPs@ZnO:Ga MWs Individual ZnO:Ga MWs with hexagonal cross-section were successfully synthesized via a chemical vapor deposition (CVD) method. 24,[38][39][40] In the synthesis procedure, by employing highpurity Ga 2 O 3 (99.999%) as an efficient Ga incorporation source, a premixed high-purity powder of ZnO (99.99%), Ga 2 O 3 and graphite (C) (99.99%) with the weight ratio of 10 : 1 : 11 was used as the precursor source material. 39,41 A corundum boat was used as a container, with a Si substrate placed on the precursor mixture to collect the products.…”

“…Thereby, a single MW based heterojunction diode was fabricated. 6,23,40,42,43 Analysis instruments Single ZnO:Ga MWs, Ag nanostructures, and MWs covered by Ag nanostructures were characterized using scanning electron microscopy (SEM). The current-voltage (I-V) characteristics of the single MW based metal-MW-metal structure and the single MW based heterojunction diode were investigated using a Keysight semiconductor device analyzer (B1500A).…”