High-Current Perovskite Oxide BaTiO3/BaSnO3 Heterostructure Field Effect Transistors

Abstract

High-current molecular beam epitaxial perovskite oxide semiconductor BaTiO3/BaSnO3 heterostructure field effect transistors on SrTiO3 substrates were developed. Record high current density of $\text{I}_{{\mathrm{max}}} =406.7$ mA/mm, maximum transconductance $\text{g}_{{{\text {m}}}} =72.3$ mS/mm were achieved in a field effect transistor with gate length $\text{L}_{{{\text {g}}}} = 0.64\,\,\mu \text{m}$ , and source-drain spacing $\text{L}_{{{\text {sd}}}} = 3.5\,\,\mu \text{m}$ . The device has a low threshold voltage of $\text{V}_{{{\text {th}}}}= - 4.5$ V and the capability to modulate $5.7\times 10^{{{{13}}}}$ cm $^{{-{2}}}$ electron density in the BaSnO3 channel. The high channel current and gate modulation efficiency are attributed to the high mobility and charge density in the BaSnO3 channel and the utilization of high-k BaTiO3 ( $\varepsilon $ is in the range of 425 and 387 as the electric field increases from 46 to 85 kV/cm) layer as the gate dielectric for charge modulation. Though the device suffers from low current ON/OFF ratio and a large subthreshold swing due to the gate leakage resulted from threading dislocations, this work demonstrates the great potential of perovskite semiconductors for electronic device applications.