Wafer-scale transfer route for top–down III-nitride nanowire LED arrays based on the femtosecond laser lift-off technique

Abstract

The integration of gallium nitride (GaN) nanowire light-emitting diodes (nanoLEDs) on flexible substrates offers opportunities for applications beyond rigid solid-state lighting (e.g., for wearable optoelectronics and bendable inorganic displays). Here, we report on a fast physical transfer route based on femtosecond laser lift-off (fs-LLO) to realize wafer-scale top–down GaN nanoLED arrays on unconventional platforms. Combined with photolithography and hybrid etching processes, we successfully transferred GaN blue nanoLEDs from a full two-inch sapphire substrate onto a flexible copper (Cu) foil with a high nanowire density (~107 wires/cm2), transfer yield (~99.5%), and reproducibility. Various nanoanalytical measurements were conducted to evaluate the performance and limitations of the fs-LLO technique as well as to gain insights into physical material properties such as strain relaxation and assess the maturity of the transfer process. This work could enable the easy recycling of native growth substrates and inspire the development of large-scale hybrid GaN nanowire optoelectronic devices by solely employing standard epitaxial LED wafers (i.e., customized LED wafers with additional embedded sacrificial materials and a complicated growth process are not required).

HectoSTAR μLED Optoelectrodes for Large‐Scale, High‐Precision In Vivo Opto‐Electrophysiology

“…Towards that goal, a number of engineering challenges remain to be overcome, including the monolithic integration of multi‐color LEDs on a silicon substrate, the high‐yield transfer of μLEDs onto a flexible substrate, and a defect‐free yet flexible polymer encapsulation. Techniques for the monolithic integration of multi‐color LEDs [ 57 , 58 , 59 ] and those for the wafer‐level transfer of μLED from a rigid substrate to a flexible substrate [ 60 , 61 , 62 ] have been recently demonstrated by several research groups. We anticipate that these techniques will come to maturity in the near future and be incorporated for the fabrication of next‐generation hectoSTAR μLED optoelectrode.…”

Influence of dopant concentration on the ammonia sensing performance of citric acid-doped polyvinyl acetate nanofibers

“…XRD has been used normally to measure the crystallinity of the synthesized materials, especially inorganic materials. [76][77][78] For electrospun nanobers, XRD was employed to verify their macromolecule orientation and elucidate the inuence of the electrospinner needle length on the crystalline structure of polyvinyl alcohol (PVA) nanobrous membranes. 72 Crystallinity is a good index for the degree of structural order, in which polymer molecule orientation affects the polymer crystallization (i.e., the higher the crystallization, the less the chain entanglement).…”

Vertically Aligned n-Type Silicon Nanowire Array as a Free-Standing Anode for Lithium-Ion Batteries

“…Among the nanoscale lithography techniques (e.g., nanoimprint lithography, colloidal nanosphere lithography, and electron beam lithography), photolithography is considered the most established method [21][22][23][24]. It enables the formation of a large variety of patterns with relatively short processing time, high accuracy of structural transfer, and suitability for wafer-scale production [25]. The deposited pattern will serve as a mask in the subsequent etching step, in which the exposed Si is removed, and the pattern is transferred onto the Si wafer, resulting in the formation of vertical nanostructures on the Si substrate.…”