Impact of ALD HfO2 Gate-Oxide Geometries on the Electrical Properties and Single-Event Effects of β-Ga2O3 MOSFETs: A Simulation Study

A Sentaurus TCAD 2-D model of β-Ga2O3 metal-oxide semiconductor field-effect transistors (MOSFETs) with a polycrystalline HfO2 gate-oxide deposited using atomic layer deposition (ALD), which has a semiconductor-on-insulator (SOI) structure, is developed. The results of model shows good agreement with the DC and the AC characteristics of the fabricated device by incorporating proper parameters for the materials, as well as the device models. We also investigate and compare electrical performance of the devices with modified HfO2 gate-oxide geometries. With a reduced HfO2 coverage over the channel, the transconductance (gm) is enhanced, the threshold voltage (Vth) shifts toward a positive voltage, both of which are advantageous for device applications. Moreover, radiation effects during transient operation of the β-Ga2O3 MOSFETs are evaluated and compared for the fabricated and the modified oxide geometries by incorporating carrier generation models with heavy-ions and alpha particles.