Mengmeng Yang

Effects of NH3 annealing on interface and electrical properties of Gd-doped HfO2/Si stack

Effects of NH3 rapid thermal annealing (RTA) on the interface and electrical properties of Gd-doped HfO2 (GDH)/Si stack were investigated. The process of NH3 annealing could significantly affect the crystallization, stoichiometric properties of GDH film and the interface characteristic of GDH/Si system. NH3 annealing also led to the decrease of interface layer thickness. The leakage current density of Pt/GDH/p-Si MOS capacitor without RTA was 2×10−3 A/cm2. After NH3 annealing, the leakage current density was about one order of magnitude lower (3.9×10−4 A/cm2). The effective permittivity extracted from the C-V curves was ∼14.1 and ∼13.1 for samples without and with RTA, respectively.

Band structure and electronic characteristics of cubic La2O3 gate dielectrics epitaxially grown on InP substrates

We first reported the hetero-epitaxial growth with good lattice matching of cubic structure La2O3 dielectric ultra-thin films on InP substrates by PLD. Epitaxial relationship between the La2O3 film and InP substrate, namely [001]La2O3||[001]InP and [012]La2O3||[012]InP, and cross-section of the stack without interface layer have been revealed by RHEED and HRTEM. The band offset for La2O3/InP is evaluated to be 1.62 eV for valence band and 2.61 eV for conduction band by XPS. A leakage current of 2 × 10−4 A/cm2 at bias voltage of −1 V and small equivalent oxide thickness of 0.3 nm have been measured on the capacitors with W/La2O3/InP/Al stack.

Atomic configuration of the interface between epitaxial Gd doped HfO2 high k thin films and Ge (001) substrates

5 nm thick epitaxial Gd doped HfO2 (GHO) high k films were grown on Ge (001) substrates by pulsed laser deposition (PLD). Epitaxial growth mode and atomic microstructure at sharp interface of GHO film on Ge were investigated by reflection high energy electron diffraction (RHEED) and high resolution electron microscopy (HRTEM). The chemical bonding at the interface between GHO film and Ge substrate was identified through high resolution x-ray photoelectron spectroscopy (HRXPS). The fitted curves of Gd 3d core level provide evidence for the existence of Ge1+, Ge2+ and Ge3+ species. The atomic configuration of the interface between GHO and Ge with incomplete atomic planes has been revealed.

Epitaxial growth and characterization of Gd2O3-doped HfO2 film on Ge (001) substrates with zero interface layer

Abstract The GHO (Gd 2 O 3 -doped HfO 2 ) films were epitaxially grown on Ge (001) substrates adopting cube-on-cube mode with zero interface layer using pulsed laser deposition (PLD). Reflection high-energy electron diffraction (RHEED) and high-resolution transmission electron microscopy (HRTEM) observation revealed a sharp interface of GHO/Ge and orientation relationship corresponding to (001)GHO//(001)Ge and [011] GHO//[011]Ge. The band offset for GHO/Ge stack was evaluated to be 3.92 eV for valence band and 1.38 eV for conduction band by X-ray photoelectron spectrum. Small equivalent oxide thickness (0.49 nm) and interface state density (7×10 11 cm −2 ) were achieved from Au/Ti/GHO/Ge/Al capacitors.

Fabrication and electronic characterization of epitaxial Gd 2 O 3 -doped HfO 2 dielectrics on Si

The 5-nm-thick HfO2 film doped with 35 mol% Gd2O3 (GDH) as a high k dielectric has been epitaxially grown on Si (100) substrate by pulsed laser deposition (PLD). In situ reflection high-energy electron diffraction (RHEED) evolution of the (100)-oriented GDH during the deposition has been investigated and shows that a two-dimensional (2D) single crystalline GDH grows with a smooth surface. The in-plane orientation relationship between (100) Si substrate and (100) GDH film adopts a cube on cube mode, which is (100)GDH//(100)Si and [110]GDH//[110]Si. The capacitance-voltage (C-V) curve shows an overall dielectric constant value of 21, capacitance equivalent thickness (CET) of 0.9 nm, and a negligible flatband shift.