Interfacial study and band alignment of ultrathin La2Hf2O7 films on GaAs substrates

We report ultrathin amorphous La2Hf2O7 (LHO) films grown on p-GaAs (0 0 1) substrates as high-k gate dielectric using the pulsed laser deposition method. Interfacial characterization of the LHO/GaAs has been carried out. It shows that the interfacial layer with a thickness of less than 0.5 nm is composed of Ga2O3. Experimental results show that the 5.7 ± 0.1 eV bandgap of LHO is aligned to the bandgap of GaAs with a valence band offset of 3.15 ± 0.05 eV and a conduction band offset of 1.1 ± 0.1 eV. Capacitance-voltage and current-voltage measurements indicate that LHO could be a promising gate dielectric for GaAs metal-oxide-semiconductor devices.