Electrical properties of HfO₂/Al₂O₃ dielectrics fabricated on In_0.53Ga_0.47As by using atomic layer deposition at low temperatures (100 - 200 ◦C)

The electrical properties of HfO₂/Al₂O₃ stacked dielectrics on n-type In_0.53Ga_0.47As were investigated as a function of the atomic layer deposition (ALD) temperature, particularly within the low temperature range from 100 to 200° C. Although the capacitance equivalent oxide thickness increased due to decreases in the dielectric constants of the HfO₂ and the Al₂O₃ films, lowering the ALD temperature to 100° C improved the interface-related electrical characteristics, such as the interface state density and frequency dispersion under accumulation. In particular, a significant reduction in the leakage current was achieved at a similar physical thickness under substrate electron injection conditions, which was probably due to the improved near-interface characteristics enabled by the formation of the gate stack at a temperature of 100° C.