Atmospheric Pressure Fabrication of Large-Sized Single-Layer Rectangular SnSe Flakes

Summary

A protocol is presented demonstrating a two-step fabrication technique to grow large-sized single-layer rectangular shaped SnSe flakes on low-cost SiO₂/Si dielectrics wafers in an atmospheric pressure quartz tube furnace system.

Abstract

Tin selenide (SnSe) belongs to the family of layered metal chalcogenide materials with a buckled structure like phosphorene, and has shown potential for applications in two-dimensional nanoelectronics devices. Although many methods to synthesize SnSe nanocrystals have been developed, a simple way to fabricate large-sized single-layer SnSe flakes remains a great challenge. Herein, we show the experimental method to directly grow large-sized single-layer rectangular SnSe flakes on commonly used SiO₂/Si insulating substrates using a straightforward two-step fabrication method in an atmospheric pressure quartz tube furnace system. The single-layer rectangular SnSe flakes with an average thickness of ~6.8 Å and lateral dimensions of about 30 µm × 50 µm were fabricated by a combination of vapor transport deposition technique and nitrogen etching route. We characterized the morphology, microstructure, and electrical properties of the rectangular SnSe flakes and obtained excellent crystallinity and good electronic properties. This article about the two-step fabrication method can help researchers grow other similar two-dimensional, large-sized, single-layer materials using an atmospheric pressure system.

Introduction

Research into two dimensional (2D) materials has bloomed in recent years since the successful isolation of graphene, due to the possibility of 2D materials having superior electrical, optical, and mechanical properties over their bulk counterparts^1,2,3,4,5. 2D materials show promising applications in optoelectronic and electronic devices^6,7, catalysis and water splitting^8,9, surface-enhanced....

Protocol

Caution: Some of the chemical agents and gases used in this work are toxic, carcinogenic, flammable, and explosive. Please use all appropriate safety practices when performing a vapor transport deposition including the use of engineering controls (fume hood) and personal protective equipment (safety glasses, professional protective masks, gloves, lab coat, full length pants, and closed-toe shoes).

1. Auto-Tune Function of Temperature Controller Parameters

NOTE: Before the synthesis of SnSe flakes, the heating system of the furnace needs to be calibrated by following the manufacturer's manual.

1. Set ....

Results

Schematic diagrams of the experimental apparatus, optical images, atomic force microscopy (AFM) images, scanning electron microscopy (SEM) images, and transmission electron microscopy (TEM) images of the fabricated SnSe flakes are shown in Figure 1, Figure 2, and Figure 3. The optical images are performed by a traditional optical microscope. The eyepiece lens is 10X, and the objective lens is 20X, 50.......

Discussion

Here, the combination of a vapor transport deposition method and a nitrogen etching technique in an atmospheric pressure system is first reported. In this protocol, the critical steps are the section of the fabrication of single-layer SnSe flakes.

Although the bulk samples can be etched to form a high-quality single-layer sample, the thickness of the bulk samples should be uniform and the decomposition temperature of bulk samples should be higher than the etching temperature. The resulting sam.......

Materials

List of materials used in this article

Name	Company	Catalog Number	Comments
SnSe powder	Sigma-Aldrich	1315-06-6	(99.999%) toxic, carcinogenic
Ar gas			explosive
H2 gas			flammable, explosive
SiO2/Si wafer			300 nm thick SiO2 on heavily doped Si
Acetone	Sigma-Aldrich	67-64-1	toxic, flammable
Isopropanol	Sigma-Aldrich	67-63-0	flammable
Quartz tube	Dongjing Quartz Company, China
Ceramic boat	Dongjing Quartz Company, China
Optical microscope	Olympus, BX51
Atomic force microscopy	Bruker		Using FastScan-A probe type and ScanAsyst-air
Scanning electron microscopy	JEOL JSM-6700F
transmission electron microscopy	FEI Titan
Tube furnace	MTI Corporation