2 MHz AO $Q$ -switched ${rm TEM}_{00}$ Grazing Incidence Laser With 3 at.% Neodymium Doped Nd:YVO$_{4}$

We present a detailed experimental and theoretical study of the ultrahigh repetition rate AO $Q$ -switched ${rm TEM}_{00}$ grazing incidence laser. Up to 2.1 MHz $Q$-switching with ${rm TEM}_{00}$ output of 8.6 W and 2.2 MHz $Q$ -switching with multimode output of 10 W were achieved by using an acousto-optics $Q$ -switched grazing-incidence laser with optimum grazing-incidence angle and cavity configuration. The crystal was 3 at.% neodymium doped Nd:YVO$_{4}$ slab. The pulse duration at 2 MHz repetition rate was about 31 ns. The instabilities of pulse energy at 2 MHz repetition rate were less than ${pm}6.7hbox{%}$ with ${rm TEM}_{00}$ operation and ${pm}3.3hbox{%}$ with multimode operation respectively. The modeling of high repetition rate $Q$-switched operation is presented based on the rate equation, and with the solution of the modeling, higher pump power, smaller section area of laser mode, and larger stimulated emission cross section of the gain medium are beneficial to the $Q$-switched operation with ultrahigh repetition rate, which is in consistent with the experimental results.      

Frequencies and Wavelengths From a New Far-Infrared Lasing Gas: $^{13}$ CHD$_{2}$ OH

The first laser action produced by the partially deuterated isotopic form of methanol, $^{13}$ CHD$_{2}$ OH, has been observed. With this laser medium, eight far-infrared laser emissions were discovered having wavelengths ranging from 33.8 to 80.9 $mu$m. A three-laser heterodyne system was used to measure the frequencies for these newly discovered laser lines and are reported with fractional uncertainties of ${pm}3 times 10^{-7}$. The offset frequency of the CO$_{2}$ pump laser was measured with respect to its center frequency for each $^{13}$CHD$_{2}$OH laser emission.      

Fabrication and Characterization of Coplanar Waveguides on Silicon Using a Combination of SiO $_{2}$ and SRO $_{20}$

In this work, the use of silicon rich oxide (SRO) and chemical vapor deposition SiO$_{2}$ double layers as passivation films of coplanar waveguides (CPW) on high resistivity silicon (HR-Si) with an ${hbox{N}}^{+}$ backside is studied. The microwave performance of the fabricated CPWs is evaluated by computing the attenuation loss of the devices in the 0.045–50 GHz frequency range. Experimental results show that the ${hbox{N}}^{+}$ layer can be used without affecting CPW performance. Also, using a combined dielectric layer (SRO$_{20}$ /SiO$_{2}$ ), the attenuation losses are reduced compared to single dielectric layers.      

Experimental Demonstration of Deeply-Etched SiO$_{2}$ Ridge Optical Waveguides and Devices

Deeply-etched ${hbox{SiO}}_{2}$ optical ridge waveguides are fabricated and characterized. A detailed discussion of the fabrication process (especially for the deep etching process) is presented. The measured propagation losses for the fabricated waveguides with different core widths range from $0.33sim {hbox {0.81}}~{hbox {dB}}/{hbox {mm}}$. The loss is mainly caused by the scattering due to the sidewall roughness. The losses in bending sections are also characterized, which show the possibility of realizing a small bending radius (several tens of microns). 1 $,times {rm N}$ ( ${rm N}=2$, 4, 8) multimode interference couplers based on the deeply-etched ${hbox{SiO}}_{2}$ ridge waveguide are also fabricated and show fairly good performances.      

$S$ - and $C$ -Band Ultra-Compact Phase Shifters Based on All-Pass Networks

Ultra-compact phase shifters are presented. The proposed phase-shifting circuits utilize the lumped element all-pass networks. The transition frequency of the all-pass network, which determines the size of the circuit, is set to be much higher than the operating frequency. This results in a significantly small chip size of the phase shifter. To verify this methodology, 5-bit phase shifters have been fabricated in the $S$ - and $C$ -band. The $S$ -band phase shifter, with a chip size of 1.87 mm $,times,$0.87 mm (1.63 mm $^{2}$), has achieved an insertion loss of ${hbox{6.1 dB}} pm {hbox{0.6 dB}}$ and rms phase-shift error of less than 2.8$^{circ}$ in 10% bandwidth. The $C$ -band phase shifter, with a chip size of 1.72 mm $,times,$0.81 mm (1.37 mm $^{2}$), has demonstrated an insertion loss of 5.7 dB $pm$ 0.8 dB and rms phase-shift error of less than 2.3 $^{circ}$ in 10% bandwidth.      

High-Efficiency PFC Abatement System Utilizing Plasma Decomposition and Ca(OH)$_{2}$ /CaO Immobilization

In order to minimize contributions to global warming, it is important to develop a perfluorocompound (PFC) abatement system that can remove PFCs effectively with low electric power. We have developed a new PFC abatement system consisting mainly of a 2-MHz ICP plasma source and two Ca(OH)$_{2}$/CaO columns operated under a decompression pressure. Reactive fluorinated compounds including SiF$_{4}$ are immobilized in the Ca(OH)$_{2}$ /CaO columns without a water scrubber. Stable compounds such as CF$_{4}$ are excited by the 2-MHz ICP plasma. When the emissions from an Si oxidation film etching process chamber were treated by this abatement system, ${hbox{F}}_{2}$ equivalent removal efficiency was 99.6%, which was about one order of magnitude larger than that of a conventional abatement system. But the CO$_{2}$ equivalent removal efficiency was calculated to be 91.4% because over 95% of CO$_{2}$ equivalent emissions were caused by the plasma source power consumption of 2.4 kWh. It means that minimization of the plasma source power consumption, depending on PFC emissions, is a very effective method of minimizing contributions to global warming in a manner similar to improving the PFC removal efficiency.      

Compact Variable ${rm TE}$-${rm TM}$ Polarization Splitter Based on Simplified Coherent Coupling in Lithium Niobate

A compact-sized electrically tunable ${rm TE}$- ${rm TM}$ mode splitter composed of a mode converter and an asymmetric Y-branch structure is presented. The asymmetric Y-branch consists of a straight and a bent waveguides to split two polarization modes based on the mode-sorting effect. To shorten the device length, a simplified coherently coupled-bending structure is utilized for the bent waveguide. Experimental results show that the device length is reduced about 52%, extinction ratios of both ${rm TE}$ and ${rm TM}$ modes are higher than 25 dB, yet the applied voltage is not significantly increased.      

Performance Improvement of N-Type $hbox{TiO}_{x}$ Active-Channel TFTs Grown by Low-Temperature Plasma-Enhanced ALD

We report on performance improvement of $n$-type oxide–semiconductor thin-film transistors (TFTs) based on $hbox{TiO}_{x}$ active channels grown at 250 $^{circ}hbox{C}$ by plasma-enhanced atomic layer deposition. TFTs with as-grown $hbox{TiO}_{x}$ films exhibited the saturation mobility $(mu_{rm sat})$ as high as 3.2 $hbox{cm}^{2}/hbox{V}cdothbox{s}$ but suffered from the low on–off ratio $(I_{rm ON}/I_{rm OFF})$ of $hbox{2.0} times hbox{10}^{2}$. $hbox{N}_{2}hbox{O}$ plasma treatment was then attempted to improve $I_{rm ON}/I_{rm OFF}$. Upon treatment, the $hbox{TiO}_{x}$ TFTs exhibited $I_{rm ON}/I_{rm OFF}$ of $hbox{4.7} times hbox{10}^{5}$ and $mu_{rm sat}$ of 1.64 $hbox{cm}^{2}/hbox{V}cdothbox{s}$, showing a much improved performance balance and, thus, demonstrating their potentials for a wide variety of applications such as backplane technology in active-matrix displays and radio-frequency identification tags.      

Near-Stoichiometric Ti : LiNbO$_{3}$ Strip Waveguides Fabricated by Standard Ti Diffusion and Post-VTE

We report near-stoichiometric (NS) Ti : LiNbO$_{3}$ waveguides fabricated by indiffusion of 4-, 5-, 6-, 7- $mu{hbox {m}}$-wide 120-nm-thick Ti-strips at 1060 $^{circ}hbox{C}$ for 10 h into a congruent $hbox{LiNbO}_{3}$ (i.e., standard Ti diffusion procedure) and post-vapour-transport-equilibration (VTE) treatment at 1100 $^{circ}hbox{C}$ for 5 h. These waveguides are NS and single-mode at 1.5 $mu{hbox {m}}$, and have a loss of 1.0/0.8 dB/cm for the TM/TE mode. In the width/depth direction of the waveguide, the mode field follows a Gauss/Hermite–Gauss profile, and the Ti profile follows a sum of two error functions/a Gauss function. The post-VTE resulted in increase of diffusion width/depth by 2.0/1.0 $mu{hbox {m}}$. A two-dimensional refractive index profile in the guiding layer is suggested.      

A Comparative NBTI Study of $hbox{HfO}_{2}$, $hbox{HfSiO}_{x}$, and SiON p-MOSFETs Using UF-OTF $I_{rm DLIN}$ Technique

The time, temperature, and oxide-field dependence of negative-bias temperature instability is studied in $hbox{HfO}_{2}/hbox{TiN}$, $ hbox{HfSiO}_{x}/hbox{TiN}$, and SiON/poly-Si p-MOSFETs using ultrafast on-the-fly $I_{rm DLIN}$ technique capable of providing measured degradation from very short (approximately microseconds) to long stress time. Similar to rapid thermal nitrided oxide (RTNO) SiON, $hbox{HfO}_{2}$ devices show very high temperature-independent degradation at short (submilliseconds) stress time, not observed for plasma nitrided oxide (PNO) SiON and $hbox{HfSiO}_{x}$ devices. $hbox{HfSiO}_{x}$ shows lower overall degradation, higher long-time power-law exponent, field acceleration, and temperature activation as compared to $hbox{HfO}_{2}$, which are similar to the differences between PNO and RTNO SiON devices, respectively. The difference between $ hbox{HfSiO}_{x}$ and $hbox{HfO}_{2}$ can be attributed to differences in N density in the $hbox{SiO}_{2}$ IL of these devices.      

Impacts of $hbox{N}_{2}$ and $hbox{NH}_{3}$ Plasma Surface Treatments on High-Performance LTPS-TFT With High-$kappa$ Gate Dielectric

Low-temperature polycrystalline-silicon thin-film transistors (LTPS-TFTs) with high- $kappa$ gate dielectrics and plasma surface treatments are demonstrated for the first time. Significant field-effect mobility $mu_{rm FE}$ improvements of $sim$86.0% and 112.5% are observed for LTPS-TFTs with $hbox{HfO}_{2}$ gate dielectric after $hbox{N}_{2}$ and $ hbox{NH}_{3}$ plasma surface treatments, respectively. In addition, the $hbox{N}_{2}$ and $ hbox{NH}_{3}$ plasma surface treatments can also reduce surface roughness scattering to enhance the field-effect mobility $mu_{rm FE}$ at high gate bias voltage $V_{G}$, resulting in 217.0% and 219.6% improvements in driving current, respectively. As a result, high-performance LTPS-TFT with low threshold voltage $V_{rm TH} sim hbox{0.33} hbox{V}$, excellent subthreshold swing S.S. $sim$0.156 V/decade, and high field-effect mobility $mu_{rm FE} sim hbox{62.02} hbox{cm}^{2}/hbox{V} cdot hbox{s}$ would be suitable for the application of system-on-panel.      

$hbox{TiN/ZrO}_{2}$/Ti/Al Metal–Insulator–Metal Capacitors With Subnanometer CET Using ALD-Deposited $hbox{ZrO}_{2}$ for DRAM Applications

We provide the first report of the structural and electrical properties of $hbox{TiN/ZrO}_{2}$/Ti/Al metal–insulator–metal capacitor structures, where the $hbox{ZrO}_{2}$ thin film (7–8 nm) is deposited by ALD using the new zirconium precursor ZrD-04, also known as Bis(methylcyclopentadienyl) methoxymethyl. Measured capacitance–voltage ($C$– $V$) and current–voltage ( $I$–$V$) characteristics are reported for premetallization rapid thermal annealing (RTP) in $hbox{N}_{2}$ for 60 s at 400 $^{circ}hbox{C}$, 500 $^{circ}hbox{C}$, or 600 $^{ circ}hbox{C}$. For the RTP at 400 $^{circ}hbox{C}$ , we find very low leakage current densities on the order of nanoamperes per square centimeter at a gate voltage of 1 V and low capacitance equivalent thickness values of $sim$ 0.9 nm at a gate voltage of 0 V. The dielectric constant of $ hbox{ZrO}_{2}$ is 31 $pm$ 2 after RTP treatment at 400 $^{circ}hbox{C}$.      

180$^{circ}$ and 90$^{circ}$ Phase Shifting Networks With an Octave Bandwidth and Small Phase Errors

A new phase shifting network for both 180 $^{circ}$ and 90 $^{circ}$ phase shift with small phase errors over an octave bandwidth is presented. The theoretical bandwidth is 67% for the 180$^{circ}$ phase bit and 86% for the 90$^{circ}$ phase bit when phase errors are $pm 2^{circ}$. The proposed topology consists of a bandpass filter (BPF) branch, consisting of a LC resonator and two shunt quarter-wavelength transmission lines (TLs), and a reference TL. A theoretical analysis is provided and scalable parameters are listed for both phase bits. To test the theory, phase shifting networks from 1 GHz to 3 GHz were designed. The measured phase errors of the 180$^{circ}$ and the 90$^{circ}$ phase bit are $pm 3.5^{circ}$ and $pm 2.5^{circ}$ over a bandwidth of 73% and 102% while the return losses are better than 18 dB and 12 dB, respectively.      

Low-Threshold Strained Quantum-Well GaSb-Based Lasers Emitting in the 2.5- to 2.7-$mu$ m Wavelength Range

GaInAsSb–GaSb strained quantum-well (QW) ridge waveguide diode lasers emitting in the wavelength range from 2.51 to 2.72 $ mu{hbox {m}}$ have been grown by molecular beam epitaxy. The devices show ultralow threshold current densities of 44 $hbox{A}/{hbox {cm}}^{2}$ (${L}rightarrow infty $) for a single QW device at 2.51 $ mu{hbox {m}}$, which is the lowest reported value in continuous-wave operation near room temperature (15 $^{circ}hbox{C}$) at this wavelength. The devices have an internal loss of 3 ${hbox {cm}}^{-1}$ and a characteristic temperature of 42 K. By using broader QWs, wavelengths up to 2.72 $mu{hbox {m}}$ could be achieved.      

High-Resolution Refractive Index and Micro-Raman Spectroscopy of Planar Waveguides in KGd(WO $_{4}$) $_{2}$ Formed by Swift Heavy Ion Irradiation

We report on the characterization of planar waveguides formed in the Raman-active crystal KGd(WO$_{4}$ )$_{2}$ using swift carbon, fluorine, and oxygen ion irradiation. The characterization of the waveguiding regions was performed using high-resolution microreflectivity and micro-Raman spectroscopy. The high-resolution microreflectivity measurement fully characterizes the refractive index profile of the barrier formed by amorphization of the crystal and detects other index variations not detected by the m-line technique. Raman spectroscopy measurements reveal details of the Raman properties of the crystal in the waveguiding region in relation to the rest of the sample for the different ion irradiations. Both of these measurement techniques are shown to be important for use of KGd(WO$_{4}$) $_{2}$ in integrated Raman-active devices.      

A $Q$ -Band Four-Element Phased-Array Front-End Receiver With Integrated Wilkinson Power Combiners in 0.18-$mu{{hbox{m}}}$ SiGe BiCMOS Technology

A four-element phased-array front-end receiver based on 4-bit RF phase shifters is demonstrated in a standard 0.18- $mu{{hbox{m}}}$ SiGe BiCMOS technology for $Q$-band (30–50 GHz) satellite communications and radar applications. The phased-array receiver uses a corporate-feed approach with on-chip Wilkinson power combiners, and shows a power gain of 10.4 dB with an ${rm IIP}_{3}$ of $-$13.8 dBm per element at 38.5 GHz and a 3-dB gain bandwidth of 32.8–44 GHz. The rms gain and phase errors are $leq$1.2 dB and $leq {hbox{8.7}}^{circ}$ for all 4-bit phase states at 30–50 GHz. The beamformer also results in $leq$ 0.4 dB of rms gain mismatch and $leq {hbox{2}}^{circ}$ of rms phase mismatch between the four channels. The channel-to-channel isolation is better than $-$35 dB at 30–50 GHz. The chip consumes 118 mA from a 5-V supply voltage and overall chip size is ${hbox{1.4}}times {hbox{1.7}} {{hbox{mm}}}^{2}$ including all pads and CMOS control electronics.      

Temperature-Insensitive Dual-Comb Filter Based on Multimode Interference Ti : LiNbO $_{3}$ Waveguide

A temperature-insensitive dual-comb filter has been demonstrated for the first time by multimode interference based on a Ti : LiNbO$_{3}$ channel waveguide. The phase difference between comb filters was about 180 $^{circ}$. We only observed less than ${pm}$0.125-nm variation of the center wavelength of the filter during temperature change from 20 $^{circ}$C to 50 $^{circ}$C. The measured extinction ratio and channel spacing of the comb filter were about ${-}$25 dB and 3.2 THz, respectively.      

High-Performance Poly-Silicon TFTs Using a High-$k$ $hbox{PrTiO}_{3}$ Gate Dielectric

In this letter, a polycrystalline-silicon thin-film transistor (poly-Si TFT) with a high- $k$ $hbox{PrTiO}_{3}$ gate dielectric is proposed for the first time. Compared to TFTs with a $hbox{Pr}_{2}hbox{O}_{3}$ gate dielectric, the electrical characteristics of poly-Si TFTs with a $hbox{PrTiO}_{3}$ gate dielectric can be significantly improved, such as lower threshold voltage, smaller subthreshold swing, higher $I_{rm on}/I_{rm off}$ current ratio, and larger field-effect mobility, even without any hydrogenation treatment. These improvements can be attributed to the high gate capacitance density and low grain-boundary trap state. All of these results suggest that the poly-Si TFT with a high- $k$ $hbox{PrTiO}_{3}$ gate dielectric is a good candidate for high-speed and low-power display driving circuit applications in flat-panel displays.      

High-Performance $hbox{In}_{0.7}hbox{Ga}_{0.3}hbox{As}$ -Channel MOSFETs With High-$kappa$ Gate Dielectrics and $alpha$-Si Passivation

Long and short buried-channel $hbox{In}_{0.7}hbox{Ga}_{0.3}hbox{As}$ MOSFETs with and without $alpha$-Si passivation are demonstrated. Devices with $alpha$-Si passivation show much higher transconductance and an effective peak mobility of 3810 $hbox{cm}^{2}/ hbox{V} cdot hbox{s}$. Short-channel MOSFETs with a gate length of 160 nm display a current of 825 $muhbox{A}/muhbox{m}$ at $V_{g} - V_{t} = hbox{1.6} hbox{V}$ and peak transconductance of 715 $muhbox{S}/muhbox{m}$. In addition, the virtual source velocity extracted from the short-channel devices is 1.4–1.7 times higher than that of Si MOSFETs. These results indicate that the high-performance $hbox{In}_{0.7}hbox{Ga}_{0.3} hbox{As}$-channel MOSFETs passivated by an $alpha$ -Si layer are promising candidates for advanced post-Si CMOS applications.      

The Electrical and Interfacial Properties of Metal-High-$kappa$ Oxide-Semiconductor Field-Effect Transistors With $hbox{LaAlO}_{3}$ Gate Dielectric

$hbox{LaAlO}_{3}$ is a promising candidate for gate dielectric of future VLSI devices. In this letter, n-channel metal–oxide–semiconductor field-effect transistors with $hbox{LaAlO}_{3}$ gate dielectric were fabricated, and the electron mobility degradation mechanisms were studied. The leakage current density is $hbox{7.6} times hbox{10}^{-5} hbox{A/cm}^{2}$ at $-!$ 1 V. The dielectric constant is 17.5. The surface-recombination velocity, the minority-carrier lifetime, and the effective capture cross section of surface states were extracted from gated-diode measurement. The rate of threshold voltage change with temperature $(Delta V_{T} / Delta T)$ from 11 K to 400 K is $-!$ 1.51 mV/K, and the electron mobility limited by surface roughness is proportional to $E_{rm eff}^{-0.66}$.