Vertical GaN Nanowires and Nanoscale Light-Emitting-Diode Arrays for Lighting and Sensing Applications

Abstract

For various lighting and monolithic sensor systems application, vertically aligned three-dimensional (3D) gallium nitride (GaN)-and indium gallium nitride (InGaN)/ GaN-based LED nanowire arrays with sub-200 nm feature sizes (down to 35 nm) were fabricated using a nanosphere liftoff lithography (NSLL) technique combined with hybrid topdown etching (i.e., inductively coupled plasma dry reactive ion etching (ICP-DRIE) and wet chemical etching). Owing to the lithographic opening and well-controlled surface functionalization prior to the polystyrene nanosphere (PN) deposition, vertical GaN nanowire arrays with an area density of 9.74 × 10 8 cm −2 and an aspect ratio of >10 could be realized in a specified large area of 1.5 × 1.5 mm 2 . Optoelectrical characteristics of the nanoLEDs were further investigated in cathodoluminescence (CL) measurements, in which multiquantum well (MQW) shows a clear CL-emission at a wavelength of 465 nm. Thus, using NSLL to manufacture low-cost but highly ordered 3D GaN-based nanowires and nanoLEDs is a feasible alternative to other sophisticated but more expensive nanolithography methods.

Investigation of Electrical Behaviors Observed in Vertical GaN Nanowire Transistors Using Extended Landauer-Büttiker Formula

“…1(a)]. This approach is more beneficial compared to the direct selective area growth (SAG) that is normally used in bottom-up approach, as the composition and doping concentration of the layer stacks can be well-defined by standard planar growth process [28], [29]. Besides, it has been known that bottom-up epitaxy of nanowire structures with complicated layer compositions (i.e., including n-GaN, p-GaN, and InGaN structures) suffers from the unreliable doping control and inhomogeneous material deposition along the wire sidewalls in c-axis direction [30].…”

Single GaN Nanowires for Extremely High Current Commutation

“…[ 8,9 ] This has motivated intense research in this field in the last few years. [ 8–13 ] However, due to the complexity of the 3D nanoscale architecture sensitive to surface charge effects, the quantification of the current density in NWs is not trivial. Quantitative evaluation of the current density and analysis of the operation stability of ultrathin GaN NWs are lacking in the literature.…”

Visible Light-Driven p-Type Semiconductor Gas Sensors Based on CaFe2O4 Nanoparticles

“…Among them, light-activated sensors have shown high potential [26,27] because the possibility to drastically reduce the power consumption by scaling down the light sources (LED platforms) or the possibility to use other technologies incompatible with heat-driven sensors (i.e., functionalization) [28]. This has been supported by the fact that micro-and nano-LEDs have been continuously researched and enhanced in terms of their performance and function for sensing applications [29]. Moreover, a novel lift-off process has been recently introduced based on femtosecond laser processing [30] to obtain free-standing LED chips that can be combined with sensing active materials to develop such integrated micro-light plates [31,32].…”