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

Abstract

In this paper, we introduce very thin Indium tin oxide (ITO) layers (5, 10, and 15 nm) hybridized with a metal mesh to produce high-performance transparent conductive layers (TCLs) in near-ultraviolet light-emitting diodes (NUV LEDs). Using UV-vis-IR spectrometry, Hall measurement, and atomic force microscopy, we found that 10 nm was the optimal thickness for the very thin ITO layers in terms of outstanding transmittance and sheet resistance values as well as stable contact properties when hybridized with the metal mesh. The proposed layers showed a value of 4.56 Ω/□ for sheet resistance and a value of 89.1% for transmittance. Moreover, the NUV LEDs fabricated with the hybrid TCLs achieved ∼140% enhanced light output power compared to that of 150 nm thick ITO layers. Finally, to verify the practical usage of the TCLs for industrial applications, we packaged the NUV LED chips and obtained improved turn-on voltage (3.48 V) and light output power (∼116%) performance.

Coupled thermo–electrical analysis of highly scaled GaN micro-LEDs with meshed hybrid conductors

“…And the FE-SEM images of each mesh designs is also shown in the figure 2(c). The metal mesh is known to enhance current spreading of the transparent conductor to improve the electrical-thermal properties of the displays [26][27][28][29][30][31]. In figure 2(d), a transmission line measurement (TLM) is employed to extract the sheet resistance of the ITO and the contact resistance between the metal mesh and ITO.…”

Effect of Sheet Resistance of Indium Tin Oxide Films on Thermal Management in Optoelectronic Devices

“…3−5 However, even when a TCF has a high sheet resistance (e.g., 100 Ω/□), combining it with a metal grid can still lead to high efficiency of solar cells or LEDs. 3,4,6,7 Consequently, developing composite TCFs, which involve sandwiching a metal layer or grid between dielectric layers, represents a promising direction in TCF advancement. 8−10 TCFs can also function as heat mirrors, 11,12 but this aspect is often overlooked in the design of solar cells or LEDs.…”

“…Transparent conductive films (TCFs) are materials that possess both electrical conductivity and optical transparency, making them suitable for a range of applications including solar cells, flat-panel displays, and light-emitting diodes (LEDs). , For optimal performance of solar cells or LEDs, a TCF should have a transmittance of 90% and a sheet resistance of 10 Ω/□. − However, even when a TCF has a high sheet resistance (e.g., 100 Ω/□), combining it with a metal grid can still lead to high efficiency of solar cells or LEDs. ,,, Consequently, developing composite TCFs, which involve sandwiching a metal layer or grid between dielectric layers, represents a promising direction in TCF advancement. − TCFs can also function as heat mirrors, , but this aspect is often overlooked in the design of solar cells or LEDs. , For solar cells, a TCF that blocks solar thermal radiation is desirable as this can decrease the cell’s temperature. The output power of a solar cell typically increases with decreasing temperature at a rate of 0.1–0.65%/°C. − Conversely, for LEDs, a TCF that transmits thermal radiation from the LED itself is more beneficial as this can lower the LED’s temperature.…”

GaN based UV‐LEDs with Ni/Au Nanomeshes as Transparent p‐type Electrodes

“…Furthermore, Min et al also reported a combination of ITO and metal meshes acting as TCL in the NUV‐LED. Low sheet resistance (≈4), improved turn‐on voltage (3.65 V) as well as 40% enhanced light output power compared to conventional 150 nm ITO‐incorporated LED . As a trade‐off between the optical and electrical properties of metal NMs acting as TCE, thickness and structural morphologies of the NMs needs to be carefully designed.…”