Applied Physics Letters

Evolution of interfacial Fermi level in In0.53Ga0.47As/high-κ/TiN gate stacks

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The net charge state was probed of metal-oxide-semiconductor gate stacks consisting of In0.53Ga0.47As /high-κ dielectric/5 nm TiN, for both Al2O3 and HfO2 dielectrics, via investigation of band bending at the InGaAs/high-κ interface. Using pump-probe photoelectron spectroscopy, changes to band bending were studied for each sequential layer deposited onto the InGaAs substrate and subsequent annealing up to 600 °C. Two behavioral regions were observed in annealing studies: (1) a lower temperature (<350°C) region, attributed to changes at the high-κ/TiN interface, and (2) a higher temperature region (> 350°C), associated with a net positive charge increase within the oxide. These band bending measurements delineate the impact of processing steps inherently inaccessible via capacitance-voltage electrical characterization.