Synthesis of Lithium Phosphorus Oxynitride (LiPON) Thin Films by Li3PO4 Anodic Evaporation in Nitrogen Plasma of a Low-Pressure Arc Discharge.

Nikolay Gavrilov,Viktor Nikolkin,Andrey Chukin,Denis Butakov,Leonid Sinelnikov,Alexey Nikonov,Alexander Kamenetskikh,Petr Tretnikov

doi:10.3390/membranes12010040

Nikolay Gavrilov, Viktor Nikolkin + Show 6 more

Open Access

https://doi.org/10.3390/membranes12010040

Copy DOI

Journal: Membranes	Publication Date: Dec 28, 2021
Citations: 6	License type: CC BY 4.0

Affiliation: Institute of Reactor Materials (Russia)

Abstract

Thin amorphous films of LiPON solid electrolyte were prepared by anodic evaporation of lithium orthophosphate Li3PO4 in an arc discharge with a self-heating hollow cathode at a nitrogen pressure of 1 Pa. Distribution of the arc current between two electrodes having an anode potential provided independent control of the evaporation rate of Li3PO4 and the density of nitrogen plasma. Stabilization of the evaporation rate was achieved using a crucible with multi-aperture cover having floating potential. The existence of a threshold value of discharge current (40 A) has been established, which, upon reaching ionic conductivity over 10−8 S/cm, appears in the films. Probe diagnostics of discharge plasma were carried out. It has been shown that heating the films during deposition by plasma radiation to a temperature of 200 °C is not an impediment to achieving high ionic conductivity of the films. Dense uniform films of LiPON thickness 1 μm with ionic conductivity up to 1 × 10−6 S/cm at a deposition rate of 4 nm/min are obtained.

Highlights

IntroductionThe interest in thin-film solid electrolytes is brought about by their prospects in allsolid-state power supplies for micro- and nano-electronics and microsystem technology [1]
A solid electrolyte based on lithium phosphorus oxynitride (LiPON) has a sufficiently high ionic conductivity (>10−6 S/cm), wide electrochemical voltage window (0–5.5 V), high electronic resistance (>1014 Ω·cm), and is chemically stable [2,3]
The discharge current to the crucible necessary to achieve the required evaporation rate of Li3 PO4 after it is heated above the melting point (1220 ◦ C) was determined at N2 flow rate of 90 sccm through a hollow cathode, ensuring stable discharge operation

Summary

Introduction

The interest in thin-film solid electrolytes is brought about by their prospects in allsolid-state power supplies for micro- and nano-electronics and microsystem technology [1]. A solid electrolyte based on lithium phosphorus oxynitride (LiPON) has a sufficiently high ionic conductivity (>10−6 S/cm), wide electrochemical voltage window (0–5.5 V), high electronic resistance (>1014 Ω·cm), and is chemically stable [2,3]. LiPON films have been synthesized using various plasma-assisted deposition methods, including pulsed laser deposition [4], vapor deposition with ion beam assistance [5], electron beam evaporation [6], and plasma chemical vapor deposition [7]. The method of RF-magnetron sputtering is most widely used. It provides the best morphology of LiPON films, high ionic conductivity, and is compatible with integrated circuit manufacturing technologies [2]

Methods

Results

Discussion

Conclusion