Inversion-type indium phosphide metal-oxide-semiconductor field-effect transistors with equivalent oxide thickness of 12 Å using stacked HfAlO_x HfO₂ gate dielectric

We present InP metal-oxide-semiconductor capacitors (MOSCAPs) and metal-oxide-semiconductor field-effect transistors (MOSFETs) with stacked HfAlO_xHfO₂ gate dielectric deposited by atomic layer deposition. Compared with single Hf O2, the use of stacked HfAlO _xHfO₂ results in better interface quality with InP substrate, as illustrated by smaller frequency dispersion and lower leakage current density. The equivalent oxide thickness of MOSCAPs with 10 Å HfAlO_x 25 Å HfO₂ stacked gate dielectric is 12 Å. The MOSFETs with this gate dielectric achieve two times higher transconductance than those with single 35 Å HfO₂. They also exhibit drive current of 60 mAmm and subthreshold swing of 83 mV/decade for 5 μm gate length.