Enhanced Vertical Alignment of InGaN/GaN Nanorod LEDs Through Dielectrophoresis with Donut-Shaped Nanohole Electrodes

Dielectrophoresis (DEP) has emerged as a promising mass transfer method, leading to various studies on the alignment of nanorod light-emitting diodes (NRLs). However, most studies have focused on horizontal alignment, which limits light extraction due to a mismatch between the alignment and major emission directions of NRLs, and makes it difficult to precisely position NRLs at the desired locations. In this study, a vertical alignment strategy for NRLs with an enhanced alignment yield is presented using DEP by introducing a donut-shaped nanohole electrode (DNE) structure. The DNE comprises two electrodes separated by an insulating layer, with a central post located within each nanohole. This post prevents the NRLs from tilting and lying horizontally on the bottom electrode, thereby enabling the placement of multiple NRLs within a single nanohole. Moreover, the alignment tendency can be effectively controlled by optimizing NRL and DNE dimensions. Consequently, alignment yields of 78%, 63%, and 61% are achieved for 1 × 1, 2 × 2, and 3 × 3 DNE arrays, respectively. These results highlight the feasibility of the proposed structure for the precise positioning of the NRLs, offering a promising pathway toward ultrasmall, high-resolution display pixels for next-generation display technologies.