Jenn-Hwan Tarng’s research while affiliated with National Yang Ming Chiao Tung University and other places

This study fabricated and verified a germanium (Ge) fin field-effect transistor (FinFET) on developed GeSOI platform. The Ge FinFETs were demonstrated for radio-frequency (RF) applications with a harmonic radar tag. The relation between the detection range (R _d ), received power (P _r ), and threshold voltage (V _th ) of a diode was qualitatively discussed. To meet the requirement of a low V _th , two kinds of Ge FinFETs with different metal gates were fabricated and compared. After the evaluation of electrical characteristics of n-type and p-type Ge FinFETs with different fin numbers, a tag for harmonic radar was designed by integrating diode-connected TiN gate 1-fin Ge FinFETs (V _th = 0.1 V) with a high impedance antenna. The RF performance was evaluated at 9.4 GHz and 18.8 GHz. The results indicated a 50 % improvement in the R _d as compared to the tag using a commercial Schottky diode. Therefore, the proposed low-V _th Ge FinFET on developed GeSOI platform for complementary metal–oxide–semiconductor (CMOS) is promising for high-sensitivity harmonic radar applications.

A low-profile, wideband antenna-in-package (AiP) design is proposed for 5G mmWave mobile applications. The aperture-coupled feeding incorporated with the microstrip feed line through the slots in the ground is used to excite the patch antenna. Firstly, a thin quarter-wave shorted patch antenna (QW-SPA) with the dominant TMz1/2,0,0 mode is realized. To broaden the operating band, the QW-SPA is extended along its resonant length so that the TMz1,0,0 mode can also be excited. The offset introduced into the two slots together with the additional shorting via wall are applied to enhance the beam tilt toward the end-fire direction. The proposed single-patch design shows a wide fractional bandwidth, covering the 5G mmWave band n257 (26.5–29.5 GHz). Furthermore, to increase more beam tilt, the differential-fed, two-patch sub-array formed by two QW-SPAs spaced a half-wavelength at 28 GHz apart is also presented. Compared with the single-patch design, the beam-tilt enhancement of around 10–27 degrees is obtained over the desired frequency band with the peak gain of around 8.2 dBi for the sub-array AiP design.

Future wireless communication systems need to be redesigned for millimeter wave carrier frequencies to accommodate higher bandwidth applications. The free space power loss for higher frequencies is higher compared to the sub-6 GHz commercial wireless systems. One of the approaches to realize a feasible data link is to design and deploy high gain antennas on the transceivers responsible for communication. To design high gain antennas with small form factor, it is important to closely consider the feeding technique of the antenna. In this article, various aspects of numerous feeding techniques are illustrated. Initially, a generic layout of the specific feeding method is explained followed by the nuances of feeding line design for a range of commonly available substrates. A comparison of different feeding techniques is also presented, followed by the merits and demerits of the respective feeding technique in the context of 28 GHz based antennas. Various design examples published in the recent literature are also presented.

In this article, heterogeneous complementary field-effect-transistor (CFET) constructed by vertically stacking amorphous indium gallium zinc oxide (a-IGZO) n-channel on poly-Si p-channel with their own dielectric layer and work function metal gate inverters were demonstrated. Meanwhile, high-frequency IGZO radio frequency (RF) devices with poly-Si as guard ring material simultaneously were fabricated in the same process. High ${f}_{\text {T}}$ and ${f}_{\text {max}}$ IGZO Radio Frequency Integrated Circuits (RFICs) with the excellent on–off ratio need to be promoted by introducing fluorine-based gas. For the IGZO device in CFET, its threshold voltage can be tuned by the adjusted gate for ideal inverter operation at different supply voltage ( ${V}_{\text {DD}}$ ). Moreover, the swing of the IGZO transistor and the gain extracted from voltage transfer characteristic (VTC) curves can also be improved when the controlled gate and adjusted gate are connected as an input terminal, but the ${V}_{\text {TH}}$ tunability for the inverter is satisfied in the meantime. We also simulated 6T-SRAM circuit by SPICE model to further investigate the potential of an adjusted gate for optimizing the noise margin during SRAM operation.

A low profile and compact two‐port antenna is proposed for mmWave 5G access point applications. Since the overall space inside a typical mmWave 5G access point is limited, a small form factor based antenna module is proposed. The two‐port antenna shares a common radiator that miniaturizes the overall antenna module. The proposed antenna comprises of single‐layered asymmetric coplanar strip (ACS)‐fed shared radiator with wide operating bandwidth ranging from 25 to 31 GHz that accounts for fractional bandwidth of 21.4%. The two‐port antenna elements are oriented at right angles to each other for obtaining orthogonal pattern diversity (OPD) thereby obtaining wide angular coverage in the E‐plane. Vertical linear corrugations with varying lengths are incorporated for decreasing mutual coupling between these two antenna elements and producing a uniform high gain end‐fire radiation pattern. Isolation of around 4 dB is enhanced by insertion of these vertical corrugations. The proposed antenna attains peak gain of 7.2 dBi with high pattern integrity over the entire operational frequency band. The presented OPD antenna occupies overall area of 74.75 mm2 which is minimal. Moreover, implementation of the proposed antenna inside a typical mmWave 5G access point is also demonstrated. Simulation and measured results are presented with adequate technical explanation.

This study reports the fabrication of the high-quality hafnium dioxide (HfO2) film at room temperature (20–30 °C) using the neutral beam enhanced atomic layer deposition (NBEALD) we developed. The HfO2 film was fabricated using tetrakis(ethylmethylamino)hafnium (TEMAH) as the Hf precursor and O2 NB as the oxidant. Argon gas was used for the carrier and purge gases. The HfO2 film-deposition process consists of 5-s TEMAH feed, 5-s Ar purge, 5-s O2 gas injection, 20-s O2 neutral beam irradiation, and 5-s Ar purge. The HfO2 film exhibited a saturated growth per cycle of 0.18 nm/cycle and a high-quality film with low C contamination (2.7%), N contamination (3.9%), and a good O/Hf ratio (2.0) was achieved. The film also had an ideal refractive index of 1.9. Additionally, continuously grown high-quality HfO2 and silicon dioxide (SiO2) gate oxide films (stacked HfO2/SiO2 gate oxide film) were successfully fabricated at room temperature. This film has the potential to decrease the thermal budget, thus enabling high flexibility when designing semiconductor structures. These findings demonstrate the effectiveness of our NBEALD in forming high-k gate stack structures.

The phonon transport in the lateral direction for gap-controlled Si nanopillar/SiGe interlayer composite materials was investigated to eliminate heat generation in the channel area for advanced MOS transistors. The gap-controlled Si NP/SiGe composite layer showed 1/100 times lower thermal conductivity than Si bulk. Then, the phonon transport behavior in lateral direction could be predicted by the combination between 3-omega measurement method for thermal conductivity and Landauer approach for phonon transport in Si NP/Si0.7Ge0.3 interlayer composite structure. We found that the NP structure could regulate the phonon transport in the lateral direction by changing the NP gaps. As such, this structure achieves the first step toward phonon transport management in the same electron transportation direction of planar-type MOSFETs and represents a promising solution to heat generation for advanced CMOS devices.