L_g = 100 nm In_0.7Ga_0.3As quantum well metal-oxide semiconductor field-effect transistors with atomic layer deposited beryllium oxide as interfacial layer

In this study, we have fabricated nanometer-scale channel length quantum-well (QW) metal-oxide-semiconductor field effect transistors (MOSFETs) incorporating beryllium oxide (BeO) as an interfacial layer. BeO has high thermal stability, excellent electrical insulating characteristics, and a large band-gap, which make it an attractive candidate for use as a gate dielectric in making MOSFETs. BeO can also act as a good diffusion barrier to oxygen owing to its small atomic bonding length. In this work, we have fabricated In_0.53Ga_0.47As MOS capacitors with BeO and Al₂O₃ and compared their electrical characteristics. As interface passivation layer, BeO/HfO₂ bilayer gate stack presented effective oxide thickness less 1 nm. Furthermore, we have demonstrated In_0.7Ga_0.3As QW MOSFETs with a BeO/HfO₂ dielectric, showing a sub-threshold slope of 100 mV/dec, and a transconductance (g_m,max) of 1.1 mS/μm, while displaying low values of gate leakage current. These results highlight the potential of atomic layer deposited BeO for use as a gate dielectric or interface passivation layer for III–V MOSFETs at the 7 nm technology node and/or beyond.