Transfer of Vertically Aligned Silicon Nanowire Arrays using Sacrificial Porous Silicon Layer

Abstract

Silicon nanowires (SiNWs) are promising semiconductor material for various device applications such as Lithium-ion batteries, sensors, thermoelectric devices, and solar cells due to their unique optical, mechanical, electrical, and thermal properties. Metal-assisted chemical etching (MACE) is a low-cost process to fabricate SiNWs at room temperature on crystalline Si (c-Si) substrate. However, the c-Si substrate is rigid, fragile, and costly that preclude the use of SiNWs in flexible devices. Transfer of SiNWs arrays to another flexible, lightweight, lowcost, or transparent substrate overcomes the shortcomings and enhances the device functionality. The parent c-Si is cleaned by RCA cleaning and used repeatedly for generating more SiNWs arrays. Here, Separation of vertically aligned SiNWs arrays from Si substrate is carried out and compared for a various technique such as peeling force, and electro-assisted etching. In electroassisted etching, the vertically aligned SiNWs arrays are transferred to another low-cost substrate (e.g., glass, plastic, steel, or polymeric sheet) using a sacrificial porous Si (PSi) layer. The detached SiNWs is bonded to the low-cost substrate by gluing. Original properties and orientation of as-etched SiNWs are preserved during the transfer of SiNWs in electro-assisted etching. The morphological characteristics of SiNWs fabricated on Si substrate are compared to the transferred one on a low-cost substrate. Material characterization techniques such as FESEM, XRD, Raman, and PL confirm the integrity of the transferred SiNWs arrays.