Dual-gate Hf-doped InZnO field-effect transistors with sub-0.1 V threshold voltage shift under bias stress

This work presents a systematic investigation of Hf-doped indium-zinc oxide (IHZO) field-effect transistors to elucidate the effects of Hf incorporation on electrical performance and bias stress stability. Owing to the strong oxygen bonding capability of Hf, oxygen vacancy-related carrier generation in the channel is effectively suppressed, resulting in a positive shift in threshold voltage and a gradual reduction in field-effect mobility with increasing Hf doping concentration. By optimizing the doping level, the IHZO device achieves a favorable balance between threshold voltage and mobility, exhibiting excellent overall electrical characteristics. To further enhance electrostatic control over the channel, a dual-gate device architecture was implemented. At a channel length of 100 nm, the dual-gate IHZO transistor demonstrates superior short-channel performance, delivering a high on-state current of 386 μA/μm, a threshold voltage of +0.09 V, and a near-ideal subthreshold swing of 61 mV/dec. Bias stress measurements conducted at a high electric field of 4 MV/cm for 3600 s reveal an extremely small threshold voltage shift of only 0.01 V under positive bias stress, indicating outstanding electrical stability. Compared with previously reported short-channel oxide transistors based on different doping systems, the IHZO devices developed in this work exhibit competitive advantages in mobility, subthreshold characteristics, drive current, and bias stress reliability. These results demonstrate the potential of atomic layer deposition-enabled Hf-doped InZnO as a compelling channel material candidate for advanced nanoscale oxide electronic applications.