Tunable indirect-direct transition of few-layer SnSe via interface engineering

Area of Science:

• Materials Science
• Condensed Matter Physics
• Solid State Chemistry

Background:

• Tin selenide (SnSe) is a highly efficient thermoelectric material, abundant and long-known.
• Interest in few-layer SnSe has surged due to its potential for novel electronic properties.
• Pristine SnSe typically exhibits indirect electronic band gaps in bulk and few-layer forms.

Purpose of the Study:

• To investigate the electronic band structures of bulk and bilayer tin selenide (SnSe).
• To explore the possibility of an indirect-direct electronic band gap transition in SnSe.
• To understand how interlayer stacking influences the electronic properties of bilayer SnSe.

Main Methods:

• Utilized first-principles density functional theory (DFT) calculations.
• Analyzed the electronic band structures of bulk and bilayer SnSe with various interlayer stackings.
• Investigated the role of interlayer interaction directionality in determining electronic band features.

Main Results:

• Reported a stacking-dependent indirect-direct electronic band gap transition in bilayer SnSe.
• Demonstrated that interlayer interaction directionality dictates critical electronic band structure features.
• Showed that engineering interface stacking can yield few-layer SnSe with a direct electronic band gap.

Conclusions:

• Interface stacking engineering is key to achieving direct band gaps in few-layer SnSe.
• This study offers fundamental insights for designing SnSe-based electronic and optoelectronic devices.
• The geometry of interfaces plays a critical role in the performance of SnSe heterostructures.