HfSe₂ and ZrSe₂: Two-dimensional semiconductors with native high-κ oxides

Area of Science:

• Materials Science
• Condensed Matter Physics
• Semiconductor Technology

Background:

• Silicon's dominance in semiconductors stems from its moderate band gap and native silicon dioxide (SiO2) insulator.
• Alternative semiconductors often lack stable native oxides, necessitating deposited insulators and causing compatibility issues.

Purpose of the Study:

• To investigate hafnium diselenide (HfSe2) and zirconium diselenide (ZrSe2) as potential silicon alternatives.
• To explore their electronic properties, native dielectric compatibility, and transistor performance.

Main Methods:

• Spectroscopic and computational studies to determine electronic band structure.
• Fabrication of air-stable transistors using HfSe2 and ZrSe2 down to three-layer thickness.
• Dielectric encapsulation and electronic performance measurements.

Main Results:

• HfSe2 and ZrSe2 possess tunable band gaps (0.9–1.2 eV) suitable for semiconductor applications.
• Native high-κ dielectrics (hafnium dioxide/HfO2 and zirconium dioxide/ZrO2) were identified.
• Fabricated transistors demonstrated excellent on/off ratios (>10^6) and on-current (~30 μA/μm).
• Native oxides minimized interfacial trap effects.

Conclusions:

• HfSe2 and ZrSe2 are the first 2D materials exhibiting silicon-like electronic properties and compatibility with high-κ dielectrics.
• Their atomically thin nature offers scaling advantages.
• These materials present a promising avenue for next-generation electronics.