Depletion Mode MOSFET Using La-Doped BaSnO₃ as a Channel Material

Area of Science:

• Materials Science
• Solid-State Physics
• Device Engineering

Background:

• Barium Strontium Titanate (BaSnO3) exhibits high room-temperature mobility, making it a promising channel material for perovskite-based transistor devices.
• Field-effect transistors (FETs) are crucial components in modern electronics, and developing high-performance perovskite-based FETs is an active area of research.

Purpose of the Study:

• To demonstrate the first n-type depletion-mode FET utilizing hybrid molecular beam epitaxy grown lanthanum-doped BaSnO3 as the channel material.
• To investigate the performance characteristics and underlying transport mechanisms of these novel perovskite-based FETs.

Main Methods:

• Fabrication of heterostructure metal-oxide semiconductor FET (MOSFET) devices with a La-doped BaSnO3 channel.
• Integration of an epitaxial Strontium Titanate (SrTiO3) barrier layer and a Hafnium Dioxide (HfO2) gate dielectric.
• Characterization using temperature- and frequency-dependent transport measurements.

Main Results:

• Achieved a field-effect mobility of approximately 70 cm^2 V^-1 s^-1 at room temperature.
• Obtained a record high transconductance value exceeding 2 mS/mm at room temperature.
• Demonstrated an on/off ratio greater than 10^7 at 77 K.

Conclusions:

• The study successfully demonstrates the viability of La-doped BaSnO3 as a high-performance channel material for n-type depletion-mode FETs.
• Device performance is influenced by the conduction band offset at the BaSnO3/SrTiO3 interface and the presence of bulk and interface traps.
• These findings pave the way for advanced all-perovskite transistor applications.