Chun-Heng Chen

RF passive devices on Si with excellent performance close to ideal devices designed by electro-magnetic simulation

High quality RF inductors, very low loss and noise CPW and microstrip lines, advanced broad and narrow band filters, and ring resonators have been achieved on Si substrates, using an optimized proton implantation process. The RF performance up to 100 GHz is close to that for ideal devices designed by EM simulation for lossless substrates.

Electrical characterization of CeO2∕Si interface properties of metal-oxide-semiconductor field-effect transistors with CeO2 gate dielectric

Metal-oxide-semiconductor field-effect transistors with CeO2 gate dielectrics were fabricated. The lowest interface trap density (Dit) of CeO2∕Si interface in comparison with other high-κ gated diodes is 1.47×1012cm−2eV−1 due to the very low lattice mismatch of CeO2∕Si. The interfacial properties were characterized by gated-diode measurements. The surface recombination velocity (s0) and the minority carrier lifetime in the field-induced depletion region (τ0,FIJ) measured from the gated diodes are about 1.03×104cm∕s and 2.73×10−8s, respectively. The effective capture cross section of surface state (σs) extracted using the gated diode technique and the subthreshold swing measurement is about 8.68×10−15cm2.

Thermal annealing and grain boundary effects on ferromagnetism in Y2O3:Co diluted magnetic oxide nanocrystals

Structures and magnetic properties of Y2O3:Co nanocrystals were investigated using high resolution transmission electron microscopy, x-ray diffraction, x-ray absorption fine structures, and superconducting quantum interference device. Cobalt atoms were found to be driven by thermal annealing from interstitial locations inside the Y2O3 nanoparticles toward particle surface, where increased O vacancies surrounding Co atoms led to increased saturation magnetization. Our results strongly support a bound magnetic polaron model for ferromagnetism in diluted magnetic oxides mostly due to magnetic dopants located on the grain boundaries.

Interfacial and Electrical Characterization in Metal?Oxide?Semiconductor Field-Effect Transistors with CeO2 Gate Dielectric

Metal–oxide–semiconductor capacitors (MOSCs) and MOS field-effect transistors (MOSFETs) incorporating cerium dioxide (CeO2) dielectrics were fabricated and investigated. In this work, the electrical and interfacial properties were characterized by capacitance–voltage (C–V) and current–voltage (I–V) measurements. The density of interface trap per unit area (Nit), the density of interface trap per unit area and energy (Dit), the energy distribution of interface trap density, and the effective capture cross section (σs) were studied in details. Experimental results showed that the Nit, Dit, and σs were about 3.4×1010 cm-2, 7.3×1010 cm-2 eV-1, and 9.0×10-15 cm2, respectively. In addition, a comparison of interfacial properties among several gate dielectrics was made.

Transport properties of gallium nitride nanowire metal-oxide-semiconductor transistor

We investigated the transport properties of [112¯0]-gallium nitride (GaN)/gallium oxide (Ga2O3) single nanowire metal-oxide-semiconductor field-effect-transistor grown on (0001) sapphire substrates. With 0.1 μm gate-length and 60 nm wire-size, the device exhibits maximum transconductance of 85 μS, saturation current of 105 μA, and unity current gain bandwidth ft at 95 GHz. From a three-dimensional (3D) diffusion-and-drift model analysis, polarization-induced negative space charge of −3 × 1012 cm−2 at the back interface of GaN/sapphire, positive space charge of 7 × 1012 cm−2 at the inclined semi-polar {11¯01¯} GaN/Ga2O3 interfaces with screening by two-dimensional electron gas to keep charge neutrality were found responsible for the high-speed transport characteristics.

Reliability characterization of stress-induced charge trapping in HfO2 by electrostatic discharge impulse stresses

The charge trapping characteristics of HfO2 dielectric under the electrostatic discharge (ESD) high-field current impulses were studied. It is found that the charge trapping phenomenon is different from that of the conventional dc stress. The results show the interface-trapped charges are built at the low stress regime, but the positive oxide-trapped charges are rapidly built up while increasing the stress voltage, which eventually dominates the oxide breakdown. The origin of the positive oxide-trapped charges at the medium stress regime is most likely the hole trapping. At high stress regime, the main contribution of the positive oxide-trapped charges results from the electric-field enhanced defect generation. Using the Fowler derivative method, the degradation characteristics of HfO2 oxides under the ESD stress are investigated. Compared with SiO2, the severer ESD-induced charge trapping in HfO2 dielectric is observed which can be elucidated by the inherent bonding nature of metal oxide.

Degradation mechanisms of electron mobility in metal-oxide-semiconductor field-effect transistors with LaAlO3 gate dielectric

LaAlO3 is a promising candidate of gate dielectric for future very large scale integration devices. In this work, metal-oxide-semiconductor capacitors and transistors with LaAlO3 gate dielectric were fabricated and the electron mobility degradation mechanisms were studied. The LaAlO3 films were deposited by radio frequency magnetron sputtering. The LaAlO3 films were examined by x-ray diffraction, secondary ion mass spectroscopy, and x-ray photoelectron spectroscopy. The temperature dependence of metal-oxide-semiconductor field-effect transistors characteristics was studied from 11 K to 400 K. The rate of threshold voltage change with temperature (ΔVT/ΔT) is −1.51 mV/K. The electron mobility limited by surface roughness is proportional to Eeff−0.66 in the electric field of 0.93 MV/cm<Eeff<2.64 MV/cm at 300 K and the phonon scattering is proportional to T−5.6 between 300 and 400 K. Soft optical phonon scattering was used to explain the extra source of phonon scattering in LaAlO3-gated n-channel metal-oxide-...

The electrical and interfacial properties of metal-high-k oxide-semiconductor field effect transistors with CeO2∕HfO2 laminated gate dielectrics

Metal-oxide-semiconductor field-effect transistors with CeO2∕HfO2 laminated gate dielectrics were fabricated. The transistors have a subthreshold slope of 74.9mV/decade. The interfacial properties were measured using gated diodes. The surface state density Dit was 9.78×1011cm−2eV−1. The surface-recombination velocity (s0) and the minority carrier lifetime in the field-induced depletion region (τ0,FIJ) measured from the gated diode were about 6.11×103cm∕s and 1.8×10−8s, respectively. The effective capture cross section of surface state (σs) extracted using the subthreshold-swing measurement and the gated diode was about 7.69×10−15cm2. The effective electron mobility of CeO2∕HfO2 laminated gated transistors was determined to be 212cm2∕Vs.

Round robin study of chlorine, sulfur and carbon in copper films from Taiwan SIMS users

Abstract The round robin study of reference standards of 35 Cl , 32 S and 12 C implanted into Cu films using five SIMS instruments from Taiwan SIMS users was attempted. Significant differences in RSFs but similarity in maximum peak concentration among different instruments was observed. For 35 Cl , 32 S and 12 C measured using Cameca ims-6f, the RSF is 3.67E+19, 5.44E+20, 4.24E+21, the detection limit is 2.5E+16, 3.17E+16, 2.34E+18, and the dynamic range is 8.11E+3, 2.22E+4, 2.3E+1, respectively. The exchangeable use of RSF is recommended among model-specific instruments.

Analysis of breakdown characteristics in high-k dielectrics under electrostatic discharge impulse stress

Transmission line pulse measurements were used to investigate the reliability of the HfO2 dielectric under an electrostatic discharge event. Time-dependent dielectric breakdown of the gate oxide was characterized down to the microsecond time regime. The positive oxide-trapped charges Qot+ were observed beyond a certain electric field and the corresponding centroid evolution was examined. In the high-field stress regime, the field acceleration parameter of the HfO2 dielectric is smaller than that of the silicon oxynitride. We also demonstrated this phenomenon can be attributed to the stronger phonon-assisted tunneling process in the high-k dielectrics.