Ag-mesh-combined graphene for an indium-free current spreading layer in near-ultraviolet light-emitting diodes

Abstract

Current spreading could be improved by using Ag-mesh-combined graphene sheets due to dramatically reducing the sheet resistance.

Very thin ITO/metal mesh hybrid films for a high-performance transparent conductive layer in GaN-based light-emitting diodes

“…Figure 2(c) shows the mobility, surface charge density, and sheet resistance of ITO layers measured by Hall measurement (model: HL 5500 supplied by BIO-RAD) according to layer thickness changes. The sheet resistance values are determined by the inverse of the multiplication of the mobility values and the surface charge density values [12]. Mobility is usually inversely proportional to surface charge density because the mean free path of the electrons becomes shorter as the number of electrons is increased.…”

“…In terms of the transmittance, it is reasonable to conclude that very thin ITO layers combined with metal mesh can be used as TCLs. [12]. Mobility is usually inversely proportional to surface charge density because the mean free path of the electrons becomes shorter as the number of electrons is increased.…”

“…Herein, we present very thin high-performance ITO layers (5 nm, 10 nm, and 15 nm) combined with a metal mesh (150 nm thick Ag/5 nm thick Cr with 5 μm width and 150 μm gap) for TCLs in near-ultraviolet light-emitting diodes (NUV LEDs); in this work, we also implemented packaging of the LEDs. The optimized structure of the metal mesh has already been reported [12]. There are many advantages of very thin ITO layers/metal mesh hybrid TCLs.…”

High-performance metal mesh/graphene hybrid films using prime-location and metal-doped graphene

“…We have previously reported the successful design of a metal mesh, and solved the structural issue in GaN-based near ultra-violet light-emitting diodes (NUV LEDs) by adding a supporting layer in the metal mesh to guarantee its stable contact properties 13 . However, achieving high-performance conditions for actual optoelectronic devices still requires determining the optimum position of each material and improving its contact properties with the p-GaN layer.…”

“…Thanks to the high transparency of the hybrid films in the UV region, we were able to obtain remarkable optical properties in GaN-based NUV LEDs compared to conventional ITO. We used the metal mesh structure as reported in our previous work (150-um gap between metal lines, 5-um width for the metal line, and 150-nm thickness for the main metal line with 5-nm thickness for the very thin metal interlayers) 13 . We observed huge differences in the electrical and optical properties depending on the location of the graphene in the NUV LEDs even if each TCL showed similar sheet resistance and transmittance values, regardless of the graphene’s location.…”