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ScAlN/GaN dielectric superjunction high-electron-mobility transistors (HEMTs) with high-k passivation layer Bi1.5Zn1.0Nb1.5O7 (BZN) are demonstrated for enhancement of breakdown voltage. The BZN thin film deposited by RF magnetron sputtering has a dielectric constant of 192 after postdeposition annealing at 400 °C for 10 min. The HEMT with Lg = 200 nm and Lsd = 2.0 μ m has a maximum current density of 1.98 A/mm, a maximum transconductance of 0.52 S/mm, and a threshold voltage of Vth = −3 V. With the use of SiN/BZN/SiN sandwiched passivation layer, the average value of breakdown voltage is improved from 68.9 to 121.5 V, due to the reduction of the peak electrical field between the gate and the drain. The device has a cutoff frequency (ƒT) and maximum oscillation frequency (ƒmax) of 59 and 69 GHz, respectively. Overall, the devices exhibit a significantly higher breakdown voltage with essentially the same ƒT and ƒmax values. Pulse measurements suggest that SiN/BZN/SiN has a similar passivation effect in comparison with devices passivated by a SiN-only layer. This work demonstrates that high current and high breakdown voltage can be achieved simultaneously on semiconductor heterostructures with a high sheet charge density by integration of high-k dielectrics. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]