Glancing Angle Deposition and Growth Mechanism of Inclined AlN Nanostructures Using Reactive Magnetron Sputtering

Samiran Bairagi,Jens Birch,Fredrik Eriksson,Lars Hultman,Ching-Lien Hsiao,Kenneth Järrendahl

doi:10.3390/coatings10080768

Samiran Bairagi, Jens Birch + Show 4 more

Open Access

https://doi.org/10.3390/coatings10080768

Copy DOI

Journal: Coatings	Publication Date: Aug 7, 2020
Citations: 20	License type: CC BY 4.0

Affiliation: Thinfilm (Sweden), Linköping University

Abstract

Glancing angle deposition (GLAD) of AlN nanostructures was performed at room temperature by reactive magnetron sputtering in a mixed gas atmosphere of Ar and N2. The growth behavior of nanostructures shows strong dependence on the total working pressure and angle of incoming flux. In GLAD configuration, the morphology changed from coalesced, vertical nanocolumns with faceted terminations to highly inclined, fan-like, layered nanostructures (up to 38°); while column lengths decreased from around 1743 to 1068 nm with decreasing pressure from 10 to 1.5 mTorr, respectively. This indicates a change in the dominant growth mechanism from ambient flux dependent deposition to directional ballistic shadowing deposition with decreasing working pressures, which is associated with the change of energy and incident angle of incoming reactive species. These results were corroborated using simulation of metal transport (SiMTra) simulations performed at similar working pressures using Ar and N separately, which showed the average particle energy and average angle of incidence decreased while the total average scattering angle of the metal flux arriving at substrate increased with increasing working pressures. Observing the crystalline orientation of GLAD deposited wurtzite AlN nanocolumns using X-ray diffraction (XRD), pole-figure measurements revealed c-axis <0001> growth towards the direction of incoming flux and a transition from fiber-like to biaxial texture took place with increasing working pressures. Under normal deposition conditions, AlN layer morphology changed from {0001} to {101¯1} with increasing working pressure because of kinetic energy-driven growth.

Highlights

Understanding the growth of nanoscale materials and thin films from the vapor phase is of fundamental importance to realize practical applications
Nanostructures with tailored chirality show interesting optical phenomena [60,61] while providing additional avenues for nanoengineering and in this study we explore possibilities and important parameters for the growth of nitride semiconductor chiral nanostructures using Glancing angle deposition (GLAD) configuration
The AlN film grown at 10 mTorr working pressure highly coalesced and faceted nanocolumnar morphology, with individual

Summary

Introduction

Understanding the growth of nanoscale materials and thin films from the vapor phase is of fundamental importance to realize practical applications. There are abundant ways to grow thin films such as metal organic chemical vapor deposition (MOCVD), molecular beam epitaxy. Coatings 2020, 10, x FOR PEER REVIEW molecular beam epitaxy (MBE), electron cyclotron resonance dual-ion beam sputtering, and pulsed (MBE), electron cyclotron resonance dual-ion beam sputtering, and pulsed laser ablation. They are expensive processes requiring high process temperatures, they are expensive processes requiring high process temperatures, motivating the selection of the motivating the selection of the physical vapor deposition (PVD) route, like direct current (DC)

Methods

Results

Discussion

Conclusion