Vol. 58 No. 2

Material Science and Technology of Japan, 58（2021）59～63

17Regular Paper
Novel Crystal Phase of Tin Nitride Synthesized by Reactive Sputtering
Yasushi INOUE1,*, Osamu TAKAI2
1Department of Advanced Materials Science and Engineering, Chiba Institute of Technology, 2-17-1,

Tsudanuma, Narashino, Chiba 275-0016, Japan
2Materials and Surface Engineering Research Institute, Kanto Gakuin University, 1162-2 Ogikubo, Odawara,

Kanagawa 250-0042, Japan
Received Sep. 10, 2020; accepted Oct. 7, 2020
Abstract
Artificially synthesized tin nitride (SnN) has been reported to have a spinel Sn3N4 crystal structure. In this study, SnN
thin films with a novel crystal phase were synthesized at a substrate temperature of 723 K via a reactive sputtering
process. Quantification analyses using X-ray photoelectron spectroscopy revealed that the N/Sn ratio of the SnN film
surface was 0.92. The peaks observed in the X-ray diffraction (XRD) profile did not match patterns of any tin-relatedmaterials. Based on the XRD fitting simulation, we determined that the SnN films have a zincblende-type crystalstructure, making it the first experimental report on the binary systems of nitrogen and group 14 elements. The
fundamental electrical, optical, and mechanical properties of the SnN films were characterized, and potential
applications of the novel SnN phase were discussed.
Keywords: Tin nitride, magnetron sputtering, crystal structure, X-ray photoelectron spectroscopy, X-ray diffraction,

1.

Introduction

determined that the crystal structure of the polycrystalline SnN

Tin belongs to group 14 elements and has been utilized bywas cubic spinel Sn3N4 (space group (SG) #216, 𝐹𝑑3𝑚), whichhuman beings for a long period for various applications.

had been previously described as a hexagonal system [1–11, 13].

However, compared with alloys and oxides of tin, the physical

They also investigated the Sn–N bonding structures via

and chemical properties of tin nitride (SnN) compounds havetransmission-mode X-ray absorption fine structure experiments

rarely been investigated. A crystalline SnN material was initially[19]. After the crystal structure was determined, a rapid synthesis

reported by Lima et al. as magnetron-sputtered SnN films [1],of spinel Sn3N4 by solid-state metathesis reactions was recentlyfollowed by studies that examined the properties of films

reported [20]. Shemkunas et al. measured the mechanicalsynthesized by the same process [2–7]. The chemical vapor

properties of spinel Sn3N4 using a nanoindentation techniquedeposition process has also succeeded in the preparation of[21]. Additionally, theoretical calculations on the structure andpolycrystalline SnN films [8–11]. Concerning the application ofproperties of spinel Sn3N4 have been carried out [22]. Huang andSnN thin films, studies have investigated their electrochromic

Feng examined polymorphs of spinel Sn3N4 and determined thatbehavior [12], including the feasibility for optical recording

CaFe2O4- and CaTi2O4-type crystal structures can be expected tomedia [4, 13], protein-binding properties for biochips [14–15],

be high-pressure phases [23]. To the best of our knowledge, there

electrode characteristics in thin-film batteries [16], and a

are no reports in the literature on the successful synthesis of any

candidate for green photovoltaic materials [17].

polymorphs of the spinel Sn3N4 phase.

In 1999, Scotti et al. reported the crystal structure of a SnN

In this paper, we report the synthesis of a novel crystal phasecompound obtained by the reaction of SnI4 with KNH2 in liquidof SnN films synthesized by reactive radio frequency (RF)ammonia [18]. Using neutron and X-ray diffraction (XRD), theymagnetron sputtering at a substrate temperature of 723 K. We
refer to this crystal phase as the high-temperature phase of SnN*Corresponding author: (inoue.yasushi@it-chiba.ac.jp)(59)