First Demonstration of Top-Gate Indium-Tin-Oxide RF Transistors with Record High Cut-off Frequency of 48 GHz, Id of 2.32 mA/μm and gm of 900 μS/μm on SiC Substrate with Superior Reliability at 85 °C

We have provided the first demonstration of high-performance top-gate indium-tin-oxide (ITO) radio-frequency (RF) transistors. The top-gate ITO transistors on SiC substrate with optimized high-κ atomic layer deposition (ALD) grown HfLaO exhibit significant improvement in not only output performance but also reliability including positive bias temperature instability (PBTI) and hot carrier degradation (HCD) at both room temperature and 85 °C. Top-gate ITO transistor on SiC substrate with high thermal conductivity shows a clear advantage in mitigating hot carrier effect, especially at high drive current for short-channel transistors. The 100 nm channel transistor shows negligible HCD, where the changes of output current (I d ) and transconductance (g m ) are less than 5% at 85 °C, a 5 times reduction from that on SiO 2 /Si substrate. Finally, the shortest 60 nm channel ITO transistor on SiC substrate exhibits record-high output current I d of 2.32 mΑ/μm and g m of 900 μS/μm at drain bias of 1 V at 85 °C. Furthermore, the RF ITO transistors on SiC substrates have achieved record high f T up to 48 GHz, the highest among all amorphous oxide semiconductor (AOS) transistors.