An interfacial self-cleaning phenomenon was found in the atomic layer deposition of HfO2 on In0.15Ga0.85As∕GaAs substrate using Hf(NCH3C2H5)4, i.e., TEMAH, and H2O as the precursors. The native oxides of InGaAs were all satisfactorily removed from the interface through ligand exchange (substitution) reactions with the TEMAH precursor. It relieves the Fermi-level pinning in the HfO2∕InGaAs heterostructure, as verified by the clear transition from accumulation to depletion in high-frequency capacitance-voltage relations and inversion in quasistatic measurement. A very low leakage current was also found from the metal-oxide-semiconductor capacitors of Au∕Ti∕HfO2∕InGaAs.

The valence-band offset has been determined to be 3.83± 0.05 eV at the atomic-layer-deposition Al 2 O 3 / InGaAs interface by x-ray photoelectron spectroscopy. The Au-Al 2 O 3 / InGaAs metal-oxide-semiconductor diode exhibits current-voltage characteristics dominated by Fowler-Nordheim tunneling. From the current-voltage data at forward and reverse biases, a conduction-band offset of 1.6± 0.1 eV at the Al 2 O 3-InGaAs interface and an electron effective mass ϳ0.28± 0.04m 0 of the Al 2 O 3 layer have been extracted. Consequently, combining the valence-band offset, the conduction-band offset, and the energy-band gap of the InGaAs, the energy-band gap of the atomic-layer-deposited Al 2 O 3 is 6.65± 0.11 eV.

Self-aligned inversion-channel In0.53Ga0.47As metal-oxide-semiconductor field-effect transistors (MOSFETs) using ultrahigh-vacuum deposited Al2O3∕Ga2O3(Gd2O3) (GGO) dual-layer dielectrics and a TiN metal gate were fabricated. For a In0.53Ga0.47As MOSFET using a gate dielectric of Al2O3(2nmthick)∕GGO(5nmthick), a maximum drain current of 1.05A∕mm, a transconductance of 714mS∕mm, and a peak mobility of 1300cm2∕Vs have been achieved, the highest ever reported for III-V inversion-channel devices of 1μm gate length.

Atomic-layer-deposited high dielectric HfO 2 films on air-exposed In 0.53 Ga 0.47 As/ InP ͑100͒, using Hf͑NCH 3 C 2 H 5 ͒ 4 and H 2 O as the precursors, were found to have an atomically sharp interface free of arsenic oxides, an important aspect for Fermi level unpinning. A careful and thorough probing, using high-resolution angular-resolved x-ray photoelectron spectroscopy ͑XPS͒ with synchrotron radiation, however, observed the existence of Ga 2 O 3 , In 2 O 3 , and In͑OH͒ 3 at the interface. The current transport of the metal-oxide-semiconductor capacitor for an oxide 7.8 nm thick follows the Fowler-Nordheim tunneling mechanism and shows a low leakage current density of ϳ10 −8 A / cm 2 at V FB + 1 V. Well behaved frequency-varying capacitance-voltage curves were measured and an interfacial density of states of 2 ϫ 10 12 cm −2 eV −1 was derived. A conduction-band offset of 1.8Ϯ 0.1 eV and a valence-band offset of 2.9Ϯ 0.1 eV have been determined using the current transport data and XPS, respectively.

Articles you may be interested inSurface band bending and band alignment of plasma enhanced atomic layer deposited dielectrics on Ga-and N-face gallium nitride X-ray photoelectron spectroscopy ͑XPS͒ combined with reflection electron energy loss spectroscopy ͑REELS͒ were used to determine the energy-band parameters, valence-band offsets ⌬E V , conduction-band offsets ⌬E C , and energy-band gaps E g , of the atomic layer deposited ͑ALD͒ Al 2 O 3 and HfO 2 on In x Ga 1−x As ͑x = 0, 0.15, 0.25, and 0.53͒. Using REELS, E g values of the ALD-Al 2 O 3 and -HfO 2 were estimated to be 6.77 and 5.56Ϯ 0.05 eV, respectively. The ⌬E V 's were determined by measuring the core level to valence band maximum binding energy difference from the XPS spectra. The ⌬E C 's were then extracted from ⌬E V 's and the energy-band gaps of the oxides and In x Ga 1−x As, and are in good agreement with those estimated from the Fowler-Nordheim tunneling. The ⌬E C 's and ⌬E V 's are larger than 1.5 and 2.5 eV, respectively, for all the ALD-oxide/In x Ga 1−x As samples.