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

High-current molecular beam epitaxial perovskite oxide semiconductor BaTiO ₃ /BaSnO ₃ heterostructure field effect transistors on SrTiO ₃ 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 BaSnO ₃ channel. The high channel current and gate modulation efficiency are attributed to the high mobility and charge density in the BaSnO ₃ channel and the utilization of high-k BaTiO ₃ ( $\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.