Graphoepitaxially Side‐By‐Side Nanofins Along Atomic Terraces for Enhancement‐Mode FinFETs with 10⁸ On/Off Ratio

Abstract

The innovation of 3D FinFETs using top‐down silicon nanofins represents a significant advancement toward scaling down microchip process nodes to the cutting‐edge 3‐nm level. While bottom‐up semiconductor nanofins also hold promise as building blocks for FinFETs, their controlled growth remains challenging. Drawing inspiration from the guided roots along brick gaps, this study shows that the aligned atomic terraces on an annealed miscut LaAlO3 surface can trigger an exceptional graphoepitaxial effect, encouraging the bottom‐up vapor‐phase growth of self‐aligned nanostructures such as CdS, CdSe, ZnSe, and ZnTe. Subsequently, the resultant CdS nanofins, characterized by narrow widths of ≈20 nm and large height‐to‐width ratios exceeding 16, can be seamlessly assembled into arrayed FinFETs on the insulating LaAlO3 substrate, obviating the need for post‐growth alignment steps. Unlike most nanostructure‐based planar transistors, which often operate in depletion mode characterized by negative thresholds, these FinFETs operate in enhancement mode with positive thresholds (≈5 V), ≈10−14‐A standby currents, and ≈108 on/off current ratios. The achieved ratio surpasses the record for planar enhancement‐mode CdS transistors by 4 orders of magnitude, primarily due to the enhanced electrostatic control over the nanofins. Overall, the graphoepitaxially side‐by‐side nanofins show tremendous potential to expand the repertoire of FinFETs based on non‐silicon semiconductors.

Horizontally Oriented Growth of Highly Conductive MoO2 Nanobelts on Sapphire

“…35 Xu et al reported that the horizontally grown CdS nanowalls with graphoepitaxy exhibited better field effect transistor performance than the planar CdS transistors in enhancement mode due to their unique features of guided nanowalls. 24,28 To the best of our knowledge, controlling the growth direction of 1D MoO 2 nanostructures by tailoring surface properties of substrates has not been reported. properties of directionally grown 1D MoO 2 nanostructures, including in situ conductivity, polarized Raman, etc., need to be further investigated.…”

“…They later achieved the guided growth of millimeter-long GaN nanowires along the nanogrooves of the annealed M-plane (101̅0) sapphire . Up to now, the generality of graphoepitaxial growth has been widely demonstrated in the horizontally oriented growth of various 1D inorganic (e.g., ZnTe, ZnSe, ZnO, CdSe, and CdS) or organic (e.g., metal phthalocyanines, Alq3) nanowires on various substrates (such as SiC, quartz, and spinel). − ,,,− …”