Sa Hoang Huynh

Effects of In-Situ Plasma-Enhanced Atomic Layer Deposition Treatment on the Performance of HfO 2 /In 0.53 Ga 0.47 As Metal–Oxide–Semiconductor Field-Effect Transistors

In-situ plasma-enhanced atomic layer deposition (PEALD) technique was employed for device passivation to realize a high-performance inversion-mode HfO2/In0.53Ga0.47As metal-oxide-semiconductor field-effect transistor (MOSFET). Excellent quality of gate dielectric is enabled by utilizing the PEALD-aluminum nitride as a pre-gate interfacial layer, followed by a post-gate remote-plasma gas treatment. In-situ PEALD treatment led to enhanced dc characteristics, such as drain current, peak transconductance, subthreshold swing, OFF leakage current, and effective electron mobility. X-ray photoelectron spectroscopy analysis indicates a reduction of In- and Ga-related signals. Furthermore, small drain current hysteresis and low-interface state density (Dit) value confirm a high interfacial quality for the high-k/III-V structure. Overall, the PEALD passivation for HfO2/In0.53Ga0.47As interface shows a remarkable improvement on the MOSFET performance.

Methods for Extracting Flat Band Voltage in the InGaAs High Mobility Materials

Accurate determination of the flat band voltage (VFB) is very important for extracting the effective work function of metal, and it will affect the prediction of the threshold voltage of the metal-oxide-semiconductor (MOS) devices. A modified method to accurately determine VFB of the In0.53Ga0.47As n-type MOS device is presented. The effects of capacitance voltage hysteresis and interface trap density at the oxide/semiconductor interface on the accuracy of the extracted VFB values are discussed. The results are also applicable to other MOS devices with high mobility channel materials.

Investigation of Multilayer TiNi Alloys as the Gate Metal for nMOS In 0.53 Ga 0.47 As

To achieve low power consumption for CMOS devices, the gate metals must have effective work function (EWF) aligned with the band edges of the channel material and have a small WF variation (WFV). The multilayer TiNi alloys have been successfully applied as the gate metals for HfO2/In0.53Ga0.47As MOS devices in this paper. The EWF of TiNi alloys was found to increase from 4.41 eV for as-deposited sample to 4.62 eV after the alloy was annealed due to the diffusion of Ni atoms into Ti layer. The multilayer TiNi alloy remained amorphous phase with small WFV until annealed at 600 °C. The TiNi alloy is thermally more stable as compared with either Ti or Ni metal, because the TiOxNi interfacial layer prevents the diffusion of Ni atoms into HfO2 film and the further reaction of Ti with HfO2. The results can be applied for InGaAs nMOS fabrication.

Impact of interfacial misfit dislocation growth mode on highly lattice-mismatched InxGa1-xSb epilayer grown on GaAs substrate by metalorganic chemical vapor deposition

Highly lattice-mismatch (over 8%) ternary InxGa1-xSb alloy directly grown on GaAs substrates was demonstrated by metalorganic chemical vapor deposition (MOCVD). The influence of growth parameters, such as growth temperature, indium vapor composition, and V/III ratio, on the film properties was investigated, and it was found that the growth temperature has the strongest effect on the surface morphology and the crystal quality of the InxGa1-xSb epilayer. An optimized growth temperature of ∼590 °C and a V/III ratio of 2.5 were used for the growth of the InxGa1-xSb epilayer on GaAs that displays a lower surface roughness. High-resolution transmission electron microscopy micrographs exhibit that InxGa1-xSb epilayer growth on GaAs was governed by the interfacial misfit dislocation growth mode. Furthermore, the variation of the intermixing layer thickness at the InxGa1-xSb/GaAs heterointerface was observed. These results provide an information of growing highly lattice-mismatched epitaxial material systems by MO...

Investigation of Mo/Ti/AlN/HfO 2 High-k Metal Gate Stack for Low Power Consumption InGaAs NMOS Device Application

Use of the Mo/Ti/AlN/HfO2 metal/dielectric stack to increase the permittivity of HfO2 for low power consumption InGaAs-based MOSFET is investigated in this letter. The dielectric constant of HfO2 was found to increase by 47%, from 17 to 25, after Ti doping without affecting the interface trap density around the mid-gap of the MOSCAPs. A strong inversion behavior with low leakage current for the MOSCAP was also observed. The gate voltage needed to tune the Fermi level of InGaAs channel was found to be smaller for the Ti-doped HfO2 sample as compared with the sample with un-doped HfO2. The increase of the dielectric constant of HfO2 after Ti doping combined with the use of Ti gate metal, which has the work function level near the conduction band edge of InGaAs, makes the proposed Mo/Ti/HfO2 (Ti) stack ideal for future lowpower consumption InGaAs-based NMOS applications.

Materials growth and band offset determination of Al2O3/In0.15Ga0.85Sb/GaSb/GaAs heterostructure grown by metalorganic chemical vapor deposition

The ternary InxGa1-xSb epilayers grown on GaAs substrates by metalorganic chemical vapor deposition using a GaSb buffer layer have been demonstrated. High–resolution transmission electron microscopy micrographs illustrate an entirely relaxed GaSb buffer grown by the interfacial misfit dislocation growth mode. A high quality In0.15Ga0.85Sb epilayer was obtained on the GaSb surface with the very low threading dislocation densities (∼8.0 × 106 cm−2) and the surface roughness was 0.87 nm. The indium content of the InxGa1-xSb epilayer depends significantly on the growth temperature and approaches to a saturated value of 15% when the growth temperature was above 580 °C. Based on the X-ray photoelectron spectroscopy analyses, the valence band offset and the conduction band offset of Al2O3 with the In0.15Ga0.85Sb/GaSb/GaAs heterostructure are 3.26 eV and 2.91 eV, respectively. In addition, from the O1s energy-loss spectrum analysis, the band gap of Al2O3 is found to be ∼6.78 ± 0.05 eV.

Study of the interface stability of the metal (Mo, Ni, Pd)/HfO2/AlN/InGaAs MOS devices

The degeneration of the metal/HfO2 interfaces for Mo, Ni, and Pd gate metals was studied in this paper. An unstable PdOx interfacial layer formed at the Pd/HfO2 interface, inducing the oxygen segregation for the Pd/HfO2/InGaAs metal oxide capacitor (MOSCAP). The low dissociation energy for the Pd-O bond was the reason for oxygen segregation. The PdOx layer contains O2− and OH− ions which are mobile during thermal annealing and electrical stress test. The phenomenon was not observed for the (Mo, Ni)/HfO2/InGaAs MOSCAPs. The results provide the guidance for choosing the proper metal electrode for the InGaAs based MOSFET.