Benzocyclobutene Research Articles

Low dielectric silsesquioxane-modified benzocyclobutene composites

Benzocyclobutene (BCB) resin has been widely used as an advanced electronic packaging material due to its excellent low-dielectric (low-k) properties, good thermal stability, and high planarization. However, it is still urgent to further reduce its dielectric constant for high-frequency applications. Herein, a series of organoalkoxysilane (D4Sin)-functionalized thermosetting benzocyclobutene (BCB) resins were reported. Precursors with the large hindrance of 2,4,6,8-tetramethyl-2,4,6,8-tetravinylcyclotetrasiloxane (D4Vi) ring as the core, as well as tunable vinyl and methoxyl substituents as pendant groups, have been successfully prepared by the efficient platinum-catalyzed hydrosilylation reaction. They can further undergo the pre-polymerization via hydrolytic condensation of methoxyl groups and post-thermal curing processes via thermal-induced ring-opening and Diel-Alder reactions between vinyl groups and bis (benzocyclobutenyl) divinyltetramethylsiloxane (DVS-BCB), respectively. The fully cured materials exhibited excellent dielectric properties with a dielectric constant (Dk) of 2.20 and a dissipation factor (Df) of 7.04 × 10−4, good thermal stability (the 5% weight loss temperature, Td5 ˃ 445 °C), strong hydrophobicity (water contact angle >100°) and good mechanical properties. Compared with traditional thermosetting BCB resins, this procedure combined BCB resins with silsesquioxanes including the ladder/cage-like or network topological structures. This work provided a simple and universal method to construct intrinsically porous materials of organoalkoxysilane-functionalized BCB resins, laying the foundation for the future fabrication of ultra-low dielectric electronic packaging materials with nanoscale pores.

Highly efficient organic light emitting diodes fabricated by solution process with new hole transport materials cross-linked at 120 °C

This work presents a rational design strategy for the synthesis of three thermal cross-linkable polystyrene-based hole transport copolymers (PPPIC-co-PBCB, PPIC-co-PBCB, PBIC-co-PBCB) by a simple free radical polymerization of planar structured indenocarbazole (IC)-based monomers having extended conjugated length and thermal cross-linkable benzocyclobutene (BCB). The materials show an extremely low cross-linking temperature of 120 °C and outstanding hole mobility of 1.01⨯10−2 cm2V−1s−1 at 4.0⨯105 Vcm−1. This value is one of the highest mobilities reported for thermal cross-linked hole transport materials (x-HTMs) in the literature. The preferred horizontal orientation of transition dipole moment (TDM), which is hardly obtained in spin coated film, was successfully achieved, and used for charge transport analysis. Herein, we also confirmed that the cross-linking reaction in our x-HTMs did not have any negative effect on the mobility of the layer, a correct method for mobility calculation from the space-charge limited current (SCLC) model was suggested, and the extension of interface mixing was also estimated for the first time. Furthermore, solution-processed organic light-emitting diode (s-OLED) device employing PPPIC-co-PBCB as HTM shows ultra-efficient performance of 130.5 cdA−1 and 37.3 % external quantum efficiency. To the best of our knowledge, this result is also one of the best efficiencies for phosphorescent s-OLEDs reported. The synthetic strategy for the polymers is also very simple with the cross-linkable monomers attached to the polystyrene backbone.

P‐122: Low Cross‐Linking Temperature Hole Transport Copolymer with Exemplary Hole Transport Ability for Efficient Solution‐Processed OLED

Newly designed and synthesized hole transport material (HTM) composed of thermal cross‐linkable benzocyclobutene (BCB) [(7‐(2‐(4‐vinylbenzyl) oxy)ethoxy) bicyclo[4.2.0]octa‐1(6),2,4‐triene) and charge transport indenocarbazole (IC), having low cross‐ linking temperature of 130 °C and excellent charge transport ability (μh=1.01×10−2 cm2 V−1 s−1 at 4.0×105 Vcm−1 ), is reported in this work. Here, we also accurately predicted the cross‐linking temperature and calculated the charge transport parameters of the HTM through molecular dynamic simulation. Finally, incorporating this new HTM into solution‐processed OLED, 130.5 cdA−1 of current efficiency and 37.3 % of EQE were achieved. This result is one of the best efficiencies for phosphorescent solution‐processed OLED have been reported.

Regio-controllable [2+2] benzannulation with two adjacent C(sp3)-H bonds.

Regiocontrol in traditional cycloaddition reactions between unsaturated carbon compounds is often challenging. The increasing focus in modern medicinal chemistry on benzocyclobutene (BCB) scaffolds indicates the need for alternative, more selective routes to diverse rigid carbocycles rich in C(sp3) character. Here, we report a palladium-catalyzed double C-H activation of two adjacent methylene units in carboxylic acids, enabled by bidentate amide-pyridone ligands, to achieve a regio-controllable synthesis of BCBs through a formal [2+2] cycloaddition involving σ bonds only (two C-H bonds and two aryl-halogen bonds). A wide range of cyclic and acyclic aliphatic acids, as well as dihaloheteroarenes, are compatible, generating diversely functionalized BCBs and hetero-BCBs present in drug molecules and bioactive natural products.

A Bis-Stabilized Interface Strategy for Low-k Benzocyclobutene-Based Hollow Silica Nanocomposites

A bis-stabilized interface strategy has been proposed to prepare high-performance low-dielectric (low-k) benzocyclobutene (BCB)-based nanocomposites by a rational-designed and facile-synthesized difunctional silane modifier. Hollow silica nanoparticles (HSNs) can be efficiently surface-modified with the difunctional silane to be evenly dispersed and chemically cross-linked with the BCB resin matrix during the post-thermal curing process, finally obtaining a series of HSNs-doped organic–inorganic nanocomposites. The dielectric properties of the resultant nanocomposites can be effectively adjusted by changing the doping ratios and cavity diameters of HSNs. Compared with commercial BCB resin, the dielectric constant of resultant 0.25 wt % HSNs-doped nanocomposites with a cavity diameter of 180 nm can be greatly reduced to 2.12 by 20%, maintaining the low level (10–4 at 1 kHz) of the dielectric loss, excellent thermal stability, and hydrophobicity as well. This study provides a facile and universal strategy to fabricate low-k BCB nanocomposites for future high-density advanced packaging applications.

Performance Improvement by SiO₂ Hardmask in 100-nm InP-Based HEMTs for TMIC Applications

Benzocyclobutene (BCB) has been widely used as passivation and interlayer dielectric for sub-millimeter-wave applications and terahertz monolithic microwave integrated circuits (TMICs). In this work, the influence of BCB passivation on 100-nm InP-based high-electron-mobility transistors (HEMTs) was investigated. A set of 100-nm HEMTs with different gate recess structures were fabricated and compared. A SiO <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$_{\text{2}}$</tex-math> </inline-formula> hard mask was adopted in the gate recess, which contributed to an improved device performance after BCB passivation. DC and RF performances were characterized before and after BCB passivation. The results show that BCB passivation in the recess region degraded InP HEMTs’ performance, and a better performance was achieved by the SiO <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$_{\text{2}}$</tex-math> </inline-formula> hard mask. For traditional devices, of which the gate recess was exposed to silicon nitride (SiN <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$_{\textit{x}}\text{)}$</tex-math> </inline-formula> and BCB passivation layers, both dc and RF performances were deteriorated drastically even though the thickness of SiN <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$_{\textit{x}}$</tex-math> </inline-formula> passivation layer was increased from 20 to 50 nm. However, the SiO <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$_{\text{2}}$</tex-math> </inline-formula> hard mask preserved the device performances to a great degree, with only degradation by increased parasitic capacitances according to the small-signal equivalent model. In addition, the threshold voltage shift after BCB passivation was suppressed by the SiO <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$_{\text{2}}$</tex-math> </inline-formula> hard mask. Thus, a device structure suitable for BCB passivated TMIC applications is proposed and validated.

Flexible Ultrathin Chip-Film Patch for Electronic Component Integration and Encapsulation using Atomic Layer-Deposited Al2O3-TiO2 Nanolaminates.

Plasma-enhanced atomic layer deposition (PEALD) is utilized to improve the barrier properties of an organic chip-film patch (CFP) when it is used as an implant to prevent moisture and ions from migrating into the embedded electronic circuits. For this purpose, surface condition and material properties of eight modifications of Al2O3-TiO2 nanolaminates sequentially deposited on polyimide PI-2611 films are evaluated in detail. The effect of stress-induced warpage of the deposited Al2O3-TiO2 on the wafer level is calculated with the Stoney equation and reveals higher tensile stress values while increasing the thickness of Al2O3-TiO2 nanolaminates from 20 up to 80 nm. Contact angle measurement and atomic force microscopy are used to investigate the surface energy and wettability, as well as the surface morphology of polyimide-Al2O3-TiO2 interfaces. We show that plasma treatment of pristine polyimide leads to an enhanced adhesion force of the PEAL-deposited layer by a factor of 1.3. The water vapor transmission rate (WVTR) is determined by exposing the coated polyimide films to 85% humidity and 23 °C and yields down to 1.58 × 10-3 g(H2O)/(m2 d). The data obtained are compared with alternative coating processes using the polymers parylene-C and benzocyclobutene (BCB). The latter shows higher WVTR values of 1.2 × 10-1 and 1.7 × 10-1 g(H2O)/(m2 d) compared to the PEALD-PI-2611 systems, indicating lower barrier properties. Two Al2O3-TiO2 modifications with low WVTR values have been chosen for encapsulating the CFP substrates and exposing them in a long-time experiment to chemical and mechanical loads in a chamber filled with phosphate-buffered saline at 37 °C, pH 7.3, and a cyclically applied pressure of 160 mbar (∼120 mm Hg). The electrical leakage behavior of the CFP systems is measured and reveals reliable electrical long-term stability far beyond 11 months, highlighting the great potential of PEALD-encapsulated CFPs.

A W-Band Self-Packaged SIW-Based Slot Antenna With Gain and Bandwidth Enhancement

This study presents the design of a self-packaged substrate integrated waveguide (SIW)-based slot antenna with a low profile at the W-band. A <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$1\times $ </tex-math></inline-formula> 4 SIW slot antenna array is developed using a standard printed circuit board (PCB) process. Then, the array is embedded in a silicon wafer. The loss of the benzocyclobutene (BCB)-based coplanar waveguide with ground (CPWG) to PCB-based SIW transition is investigated and measured to interconnect and integrate the antenna array with other components. The performance of the SIW-based slot antenna is enhanced about 2 dB without extra feeding networks by using a novel method of parasitic folded patches, and the fractional impedance bandwidth is increased from 10% to 15% by changing the metallic posts besides the SIW. The antennas are fabricated using our in-house silicon-based MEMS photosensitive composite film BCB fabrication process, which is described in detail. The proposed antenna has a measured maximum gain of 11.7 dBi at 98 GHz, with a fractional impedance bandwidth of 17%. Measured results show a close relationship with the simulated values. Compared with other antennas, our proposed antenna exhibits excellent performance, such as high gain, low profile, low loss interconnection structure, and broad bandwidth. Finally, a novel heterogeneous integration transceiver application is introduced. In this application, self-packaged SIW-based slot antennas are integrated with different types of chips. This 1 transmitter and 2 receivers (1T2R) transceiver can be further used in long-range radar detection, vital sign monitoring, and synthetic aperture radar imaging.

Analysis of terahertz double dielectric structure patch antenna using nitride semiconductors

AbstractRecently, gallium arsenide (GaAs)‐based resonant tunneling diode (RTD) oscillators and indium phosphorus (InP)‐based Schottky barrier diode (SBD) receivers have been studied in the terahertz (THz) band. The THz devices for practical use should operate at room temperature, be small in size, and have high output power. Therefore, this study was focused on gallium nitride (GaN), which possesses excellent material properties, such as wide bandgap characteristics and heteroepitaxy on Si substrates. The GaN‐based oscillators and receivers are expected to be compact, operate at room‐temperature, and act as a high‐power device for the THz‐band devices. However, GaN has crystal defects, which can cause instability in device operations. A double dielectric structure patch antenna composed of Silicon Nitride (SiN) and Benzo Cyclo Butene (BCB) with different dielectric constants was proposed to realize a GaN‐based THz transmitter and receiver. The antenna characteristics were investigated using the Finite Difference Time Domain (FDTD) method. The results showed that the SiN has little effect on the radiation, whereas the BCB is strongly responsible for the radiation. Comparing the absolute gain between the double dielectric structure and the conventional structure using the SiN, it was confirmed that the double dielectric structure can improve the absolute gain.

Analysis of Crosstalk Effects for Ternary Logic MWCNT Bundled Through Silicon Vias

This article presents a technique to improve the crosstalk effects in ternary coupled through silicon vias (TSVs). The effects of crosstalk are investigated in TSVs using multi walled carbon nanotube (MWCNT) as metallic liner and polymers such as polyimide, polypropylene carbonate (PPC), benzocyclobutene (BCB) as dielectric liners. The circuit model for coupled TSVs driven by ternary inverter is utilized to analyze the various crosstalk issues. The HSPICE tool is utilized to develop the proposed TSVs. The crosstalk issues for the MWCNT TSVs are investigated and compared to single walled CNT (SWCNT) TSVs. Moreover, the power, power delay product (PDP) and energy delay product (EDP) are analyzed and compared to SWCNT TSVs. All the performances are also studied for different TSV pitches. The coupled TSVs with BCB show high performance for the large pitch values. Moreover, it is noticed that the coupled TSVs with BCB at 5000 μm TSV pitch improved the performance up to 40.03% over the SWCNT TSVs.

A low dielectric constant material synergized by calix[4]arene and benzocyclobutene units

A novel low-kmaterial (Dkis as low as 2.23) was prepared from functionalized 4-tert-butylcalix[4]arene with different numbers of benzocyclobutene (BCB) units (2 or 4) and spacers (–(CH2)3– or –(CH2)6–).

Preparation of benzocyclobutene-functionalized organic–inorganic hybrid microspheres and their reduction of permittivity to DVSBCB resin

BCB-functionalized microspheres with narrow particle size distribution are easy to synthesize and have a significant effect on reducing the dielectric constant of BCB resins.

Aerosol Jet Printing of a Benzocyclobutene‐Based Ink as Adhesive Material for Wafer Bonding Application

AbstractAerosol jet printing (AJP) is an emerging additive manufacturing technology that is gaining increasing attention in the electronic field. Several studies have been carried out on the AJP of conductive, semiconductive, and dielectric polymers for electronic applications. However, wafer bonding is an application that is still uncovered by literature. Therefore, in this work, the AJP of benzocyclobutene (BCB) as a polymeric adhesive for wafer bonding is presented for the first time. A thorough characterization of the processing parameters is carried out to identify the most ideal conditions for printing at a relatively high speed. Then, square patterns are printed, proving the versatility of the AJP technology in terms of the reachable thickness of the deposited BCB patterns. Complex patterns with a resolution of ≈60 µm are also printed. The bonding properties of the BCB are characterized from a morphological and mechanical point of view. In particular, the shear strength of the BCB coatings deposited with AJP is ≈39 MPa and it is comparable with the shear strength of BCB coating deposited by spin‐coating. Consequently, AJP represents a valid alternative for the deposition of polymeric adhesive for wafer bonding.

Analysis of Terahertz Double Dielectric Structure Patch Antenna Using Nitride Semiconductors

Recently, gallium arsenide (GaAs)-based resonant tunneling diode (RTD) oscillators and indium phosphorus (InP)-based Schottky barrier diode (SBD) receivers have been studied in the terahertz (THz) band. The THz devices for practical use should operate at room temperature, be small in size, and have high output power. Therefore, this study was focused on gallium nitride (GaN), which possesses excellent material properties, such as wide bandgap characteristics and heteroepitaxy on Si substrates. The GaN-based oscillators and receivers are expected to be compact, operate at room-temperature, and act as a high-power device for the THz-band devices. However, GaN has crystal defects, which can cause instability in device operations. A double dielectric structure patch antenna composed of Silicon Nitride (SiN) and Benzo Cyclo Butene (BCB) with different dielectric constants was proposed to realize a GaN-based THz transmitter and receiver. The antenna characteristics were investigated using the Finite Difference Time Domain (FDTD) method. The results showed that the SiN has little effect on the radiation, whereas the BCB is strongly responsible for the radiation. Comparing the absolute gain between the double dielectric structure and the conventional structure using the SiN, it was confirmed that the double dielectric structure can improve the absolute gain.

Crosslinkable benzocyclobutene based host polymer for high temporal stability of organic second-order nonlinear optical materials

Second-order nonlinear optical (NLO) materials have become a pivotal core for photonic devices with the development of the information globalization. The alignment stability of chromophores is the key factor affecting the services life of materials. Benzocyclobutene (BCB)-based resin, as a good encapsulating materials, exhibited excellent thermal stability after cross-linking reaction. BCB remains a challenge if used directly in NLO materials due to its high curing temperature. Benzocyclobutene (BCB)-based co-polymer have been synthesized and systematically investigated for improving temporal stability of NLO materials, and bismaleimide (BMI) had been introduced as curing agent for further tuning the curing temperature of BCB in this paper. As differential scanning calorimetry (DSC) curves analysis, introduction of curing agent BMI could efficiently improve reactivity of the ring-opening and then cycloaddition of BCB group leading to lower curing temperature (the peak temperature decreased from 194 °C to 160 °C), which prevent the decomposition of doped chromophore during cross-linking. Thermal stimulated depolarization (TSD) results indicated that the temporal stability of NLO materials was remarkably increased due to the cross-linked network structure.

Synthesis and characterization of thermally cross-linkable poly(iminoarylene)-based hole injection layer for solution-processed organic light-emitting diodes

A cross-linkable poly(iminoarylene), poly[(9,9-dioctyl-N-(p-tolyl)-9H-fluoren-2-amine)–co-(9,9-bis(4-(bicyclo[4.2.0]octa-1(6),2,4-trien-7-yloxy)phenyl)-N-(p-tolyl)-9H-fluoren-2-amine)] [poly(FA-co-BFA)], was synthesized as a hole injection layer (HIL) for solution-processed organic light-emitting diodes (OLEDs). Poly(FA90-co-BFA10) containing 10 mol% of benzocyclobutene (BCB) which is a thermally curable functional group was used in this study. The highest occupied molecular orbital (HOMO) and lowest unoccupied molecular orbital (LUMO) energy levels of poly(FA90-co-BFA10) were measured to be −5.14 and −2.31 eV, respectively. After heating at 150 °C for 40 min, the spin-cast poly(FA90-co-BFA10) film became completely crosslinked without requiring the use of additional initiators. The crosslinked thin film showed good film-forming properties and excellent solvent resistance (up to 99 %). A photo-crosslinked poly[bis(4-butypheny)-bis(phenyl)benzidine] (poly-TPD) was used as the hole-transporting layer (HTL) on top of the crosslinked poly(FA90-co-BFA10). Finally, a solution-processed red phosphorescent OLED device with the structure of indium tin oxide/poly(FA90-co-BFA10)/poly-TPD/emissive layer/TPBi/LiF/Al was fabricated and characterized. The device showed a low turn-on voltage (Von) of 3.5 V, a reasonably high current efficiency (CE) of 16.6 cd/A, and an external quantum efficiency (EQE) of 12.5 %, which are better than those of the corresponding reference device using PEDOT:PSS as the HIL. Moreover, the device fabricated using the poly(FA90-co-BFA10) HIL demonstrated a longer lifetime than that fabricated using PEDOT:PSS.

Analysis of BCB and SU 8 photonic waveguide in MZI architecture for point-of-care devices

The proposed refractive index-based biosensor made of cost-effective polymer material in Mach-Zehnder configuration with novel horizontal slot waveguide structure offers high sensitivity. Due to the recent demand for low-cost point-of-care biosensor, silicon wafer-based polymer material has the potential for developing new hybrid waveguides for sensors. Hence we designed BenzoCycloButene (BCB), SU8 material as the core, and polymethyl methacrylate (PMMA) clad on a silicon wafer. The novelty of proposed BCB and SU8 horizontal slot waveguide structure of 2.5 μ m wide and 1.8μ m thick with a slot height of 400 ​nm, which handles the analyte effectively without any external sample holder. In Mach-Zehnder Interferometer architecture, reference arm 1 ​cm and sensing arm at a length of 1.1 ​cm with analyte refractive index of cancer cell (RI ​= ​1.401) and Influenza A type virus (RI ​= ​1.48) are used. Effective mode index of BCB core and SU8 are investigated through Finite-difference time domain (FDTD) analysis, and sensitivity results are calculated. Detection of disease are plotted in the transmission spectrum with reference to normal human serum (RI ​= ​1.35). This horizontal slot waveguide of BCB core achieves a sensitivity of 19280 nm/RIU and SU8 horizontal slot core waveguide provides a sensitivity of 16500 nm/RIU, which is higher in this polymer based refractive index biosensing.

BCB-Based Thin-Film Ka-Band Quarter-Mode SIW Packaged Filters With Ultrawide Stopband and Independently Controlled TZs

In this article, quarter-mode substrate-integrated waveguide (QMSIW) filters featuring ultrawide stopband and flexibly allocated transmission zeros (TZs) are proposed. Eight higher modes with resonant frequencies up to 4.7 times of the fundamental mode are highly suppressed. It is realized by the combination of three approaches without extra circuit areas. First, a slot is cut in the first and last QMSIW resonators to make their resonant frequencies of higher modes different from those of other resonators. Second, avoid exciting the specific higher modes by setting the feed point in the area where the electric field strength of the higher modes is weak. Third, mismatch the higher modes when matching the passband. It is realized by using a stripline impedance transformer with its main body not exceeding the area of QMSIW resonators. Furthermore, except for the TZs derived by the classical cross-coupling matrix, two more independently controlled TZs are generated. The packaged filter is fabricated by using a benzocyclobutene (BCB)-based microelectromechanical systems (MEMS) process, which is suitable for millimeter-wave 3-D system-on-package (SOP) applications. The fabricated thin-film filter is measured with an insertion loss of 2.96 dB at 29.4 GHz and a fractional bandwidth (BW) of 17%. Higher mode suppressions up to 138.3 GHz are achieved.

Fabrication of polymeric vacuum-sealed cavities on a silicon wafer

A method to fabricate low temperature adhesively bonded vacuum-sealed insulated polymeric cavities on a silicon substrate is presented. Multi-purpose use of the same polymer (Benzocyclobutene (BCB)) as the cavity structural material and also as an adhesive bonding agent minimizes process complexity, cost, and dielectric charging. Scanning electron microscopy (SEM) based characterization results show excellent planarity of BCB surfaces and high quality bonding which is indicative of better reliability. The method paves the way to fabricate the package and the sensor in the same process run to enable higher level of integration and minimize the cost further. The technique can be used to realize capacitive micromachined ultrasonic transducers (CMUTs), MEMS pressure sensors, and 3D embedded packaging and integration of heterogeneous dies.

High-temperature and high-efficiency operation of a membrane optical link with a buried-ridge-waveguide bonded on a Si substrate.

We demonstrate a membrane photonic integrated circuit (MPIC) that includes a membrane distributed feedback (DFB) laser and a p-i-n photodiode with a buried-ridge-waveguide (BRW) on a Si substrate, using a-Si nanofilm-assisted room-temperature surface activated bonding (SAB) for on-chip optical interconnection. The BRW structure enhanced the lateral optical confinement compared with that of the conventional flat structure. The directly bonded membrane DFB laser using SAB had a lower thermal resistance and higher output power than the previous structure using a benzocyclobutene (BCB) bonding layer. The DFB laser had a low threshold current of 0.27 mA at 25 °C. The maximum detected photocurrent and slope efficiency were 0.95 mA and 0.203 mA/mA, respectively, at 25 °C. The MPIC was successfully operated at temperatures up to 120 °C. The 3-dB bandwidths of 16.8 GHz and 10.1 GHz were achieved at 25 °C and 80 °C, respectively, and 25 Gbps and 15 Gbps non-return-to-zero (NRZ) 215-1 pseudo-random bit sequence signals were recorded at 25 °C and 80 °C, respectively.