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.      

$hbox{TiN/ZrO}_{2}$/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 $^{circ}hbox{C}$.      

Electrical Properties of $hbox{Bi}_{5}hbox{Nb}_{3} hbox{O}_{15}$ Thin Film Grown on $hbox{TiN}/hbox{SiO}_{2}/ hbox{Si}$ at Room Temperature for Metal–Insulator–Metal Capacitors

Buckling was observed in $hbox{Bi}_{5}hbox{Nb}_{3}hbox{O}_{15}$ (BiNbO) films grown on $hbox{TiN}/hbox{SiO}_{2}/hbox{Si}$ at 300 $^{circ}hbox{C}$ but not in films grown at room temperature and annealed at 350 $^{circ}hbox{C}$. The 45-nm-thick films showed a high capacitance density and a low dissipation factor of 8.81 $hbox{fF}/muhbox{m}^{2}$ and 0.97% at 100 kHz, respectively, with a low leakage current density of 3.46 $hbox{nA}/hbox{cm}^{2}$ at 2 V. The quadratic and linear voltage coefficients of capacitance of this film were 846 $hbox{ppm}/hbox{V}^{2}$ and 137 ppm/V, respectively, with a low temperature coefficient of capacitance of 226 $hbox{ppm}/^{circ}hbox{C}$ at 100 kHz. This suggests that a BiNbO film grown on a $hbox{TiN}/ hbox{SiO}_{2}/hbox{Si}$ substrate is a good candidate material for high-performance metal–insulator–metal capacitors.      

Cooperative Quantum Cutting in Yb $^{3+}$–Tb $^{3+}$ Codoped Borosilicate Glasses

Quantum cutting down-conversion (DC) with the emission of two near-infrared photons for each blue photon absorbed is realized in $hbox{Yb}^{3+}hbox{–}hbox{Tb}^{3+}$ codoped borosilicate glasses. With the excitation of $hbox{Tb}^{3+}$ ion by a 484-nm monochromatic light, emission from the $^{2} hbox{F} _{5/2}rightarrow ^{2} hbox{F} _{7/2}$ transition of $hbox{Yb}^{3+}$ ions is observed and this emission is proved to originate from the DC between $hbox{Tb}^{3+}$ ions and $hbox{Yb}^{3+}$ ions. Results shows that maximum quantum efficiency reach as high as 153%, which is comparable with that in oxyfluoride glass ceramics in this system. With the advantages of excellent transparence, easy shaping, good stability, and low cost, $hbox{Yb}^{3+}hbox{–}hbox{Tb}^{3+}$ codoped borosilicate glasses are potentially used as down-converter layer in silicon-based solar cells.      

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.      

Extraction of the Effective Mobility of $ hbox{In}_{0.53}hbox{Ga}_{0.47}hbox{As}$ MOSFETs

The extraction of the effective mobility on $hbox{In}_{0.53} hbox{Ga}_{0.47}hbox{As}$ metal–oxide–semiconductor field-effect transistors (MOSFETs) is studied and shown to be greater than 3600 $hbox{cm}^{2}/hbox{V} cdot hbox{s}$. The removal of $C_{rm it}$ response in the split $C$–$V$ measurement of these devices is crucial to the accurate analysis of these devices. Low-temperature split $C$–$V$ can be used to freeze out the $D_{rm it}$ response to the ac signal but maintain its effect on the free carrier density through the substrate potential. Simulations that match this low-temperature data can then be “warmed up” to room temperature and an accurate measure of $Q_{rm inv}$ is achieved. These results confirm the fundamental performance advantages of $hbox{In}_{0.53}hbox{Ga}_{0.47}hbox{As}$ MOSFETs.      

High-Density and Low-Leakage-Current MIM Capacitor Using Stacked $hbox{TiO}_{2}/hbox{ZrO}_{2}$ Insulators

We have fabricated high-$kappa hbox{Ni}/hbox{TiO}_{2}/hbox{ZrO}_{2}/ hbox{TiN}$ metal–insulator–metal (MIM) capacitors. A low leakage current of $hbox{8} times hbox{10}^{-8} hbox{A/cm}^{2}$ at 125 $^{circ}hbox{C}$ was obtained with a high 38- $hbox{fF}/muhbox{m}^{2}$ capacitance density and better than the $hbox{ZrO}_{2}$ MIM capacitors. The excellent device performance is due to the lower electric field in 9.5-nm-thick $hbox{TiO}_{2}/ hbox{ZrO}_{2}$ devices to decrease the leakage current and to a higher $kappa$ value of 58 for $ hbox{TiO}_{2}$ as compared with that of $hbox{ZrO}_{2}$ to preserve the high capacitance density.      

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.      

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.      

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.      

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 $E_{rm eff}^{-0.66}$.      

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.      

$S$ - 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 Conversion Efficiency InP/InGaAs Strained Quantum Well Infrared Photodetector Focal Plane Array With 9.7 $mu$m Cut-Off for High-Speed Thermal Imaging

InP/InGaAs material system is an alternative to AlGaAs/GaAs for long wavelength quantum well infrared photodetectors (QWIPs). We demonstrate a large format (640 $times$ 512) QWIP focal plane array (FPA) constructed with the strained InP/InGaAs material system. The strain introduced to the structure through utilization of $hbox{In}_{0.48}hbox{Ga}_{0.52}hbox{As}$ (instead of $hbox{In}_{0.53}hbox{Ga}_{0.47}hbox{As}$ ) as the quantum well material shifts the cut-off wavelength from $sim$8.5 to 9.7 $muhbox{m}$. The FPA fabricated with the 40-well epilayer structure yields a peak quantum efficiency as high as 12% with a broad spectral response $(Deltalambda/lambda_{rm p}=17%)$. The peak responsivity of the FPA pixels is 1.4 A/W corresponding to 20% conversion efficiency in the bias region where the detectivity is reasonably high ($2.6times 10^{10} hbox{cmHz}^{1/2}/hbox{W}$ , f/1.5, 65 K). The FPA providing a background limited performance temperature higher than 65 K (f/1.5) satisfies the requirements of most low integration time/low background applications where AlGaAs/GaAs QWIPs suffer from read-out circuit noise limited sensitivity due to lower conversion efficiencies. Noise equivalent temperature differences of the FPA are as low as 19 and 40 mK with integration times as short as 1.8 ms and 430 $muhbox{s}$ (f/1.5, 65 K).      

Nitride-Based Asymmetric Two-Step Light-Emitting Diode With In$_{0.08}$ Ga$_{0.92}$ N Shallow Step

A nitride-based asymmetric two-step light-emitting diode (LED) with $hbox{In}_{0.08} hbox{Ga}_{0.92}hbox{N}$ shallow step was proposed and fabricated. It was found that the low indium content $hbox{In}_{0.08} hbox{Ga}_{0.92}hbox{N}$ layer can significantly enhance phase separation and/or inhomogeneous indium distribution in the active $hbox{In}_{0.27}hbox{Ga}_{0.73}hbox{N}$ layer. It was also found that we can enhance LED output power by a factor of 2.27 by simply inserting an $hbox{In}_{0.08} hbox{Ga}_{0.92}hbox{N}$ shallow step.      

Compact $S$ -/$Ka$-Band CMOS Quadrature Hybrids With High Phase Balance Based on Multilayer Transformer Over-Coupling Technique

This paper presents compact CMOS quadrature hybrids by using the transformer over-coupling technique to eliminate significant phase error in the presence of low-$Q$ CMOS components. The technique includes the inductive and capacitive couplings, where the former is realized by employing a tightly inductive-coupled transformer and the latter by an additional capacitor across the transformer winding. Their phase balance effects are investigated and the design methodology is presented. The measurement results show that the designed 24-GHz CMOS quadrature hybrid has excellent phase balance within ${pm}{hbox{0.6}}^{circ}$ and amplitude balance less than ${pm} {hbox{0.3}}$ dB over a 16% fractional bandwidth with extremely compact size of 0.05 mm$^{2}$. For the 2.4-GHz hybrid monolithic microwave integrated circuit, it has measured phase balance of ${pm}{hbox{0.8}}^{circ}$ and amplitude balance of ${pm} {hbox{0.3}}$ dB over a 10% fractional bandwidth with a chip area of 0.1 mm$^{2}$ .      

A 2.4-GHz Resistive Feedback LNA in 0.13-$mu$m CMOS

A $g_{m}$-boosted resistive feedback low-noise amplifier (LNA) using a series inductor matching network and its application to a 2.4 GHz LNA is presented. While keeping the advantage of easy and reliable input matching of a resistive feedback topology, it takes an extra advantage of $g_{m}$ -boosting as in inductively degenerated topology. The gain of the LNA increases by the $Q$ -factor of the series RLC input network, and its noise figure (NF) is reduced by a similar factor. By exploiting the $g_{m}$-boosting property, the proposed fully integrated LNA achieves a noise figure of 2.0 dB, S21 of 24 dB, and IIP3 of ${- 11}~ hbox{dBm}$ while consuming 2.6 mW from a 1.2 V supply, and occupies 0.6 ${hbox {mm}}^{2}$ in 0.13-$mu{hbox {m}}$ CMOS, which provides the best figure of merit. This paper also includes an LNA of the same topology with an external input matching network which has an NF of 1.2 dB.      

Distributed-Feedback Quantum-Cascade Lasers at 9 $mu$m Operating in Continuous Wave Up to 423 K

Single-mode lasers operating at $lambdaapprox 9 muhbox{m}$ in continuous wave up to 423 K (150 $^{circ}hbox{C}$) were achieved by the combination of strong distributed-feedback coupling, a narrow gain active region design, low intersubband, and free-carrier losses as well as a good thermal management. Tuning of 10 $hbox{cm}^{-1}$ or 0.9% of the center frequency was achieved by heating the device. The threshold current density varies from 1.1 $hbox{kA/cm}^{2}$ at 303 K to 2.4 $hbox{kA/cm}^{2}$ at 423 K. Other devices with low electrical power consumption of 1.6 and 3.8 W for an optical output power of 16 and 100 mW have been demonstrated at 263 K.      

Electrical Properties of Amorphous $hbox{Bi}_{5} hbox{Nb}_{3}hbox{O}_{15}$ Thin Film for RF MIM Capacitors

Amorphous $hbox{Bi}_{5}hbox{Nb}_{3}hbox{O}_{15}(hbox{B}_{5} hbox{N}_{3})$ film grown at 300 $^{circ}hbox{C}$ showed a high-$k$ value of 71 at 100 kHz, and similar $k$ value was observed at 0.5–5.0 GHz. The 80-nm-thick film exhibited a high capacitance density of 7.8 fF/$muhbox{m}^{2}$ and a low dissipation factor of 0.95% at 100 kHz with a low leakage-current density of 1.23 nA/ $hbox{cm}^{2}$ at 1 V. The quadratic and linear voltage coefficient of capacitances of the $hbox{B}_{5}hbox{N}_{3}$ film were 438 ppm/$hbox{V}^{2}$ and 456 ppm/V, respectively, with a low temperature coefficient of capacitance of 309 ppm/$^{circ}hbox{C}$ at 100 kHz. These results confirmed the potential of the amorphous $hbox{B}_{5}hbox{N}_{3}$ film as a good candidate material for a high-performance metal–insulator–metal capacitors.      

Comparative Study of the Low-Frequency-Noise Behaviors in a-IGZO Thin-Film Transistors With $hbox{Al}_{2}hbox{O}_{3}$ and $hbox{Al}_{2}hbox{O}_{3}/hbox{SiN}_{x}$ Gate Dielectrics

A comparative study is made of the low-frequency noise (LFN) in amorphous indium–gallium–zinc oxide (a-IGZO) thin-film transistors (TFTs) with $hbox{Al}_{2}hbox{O}_{3}$ and $hbox{Al}_{2}hbox{O}_{3}/hbox{SiN}_{x}$ gate dielectrics. The LFN is proportional to $hbox{1}/f^{gamma}$, with $gamma sim hbox{1}$ for both devices, but the normalized noise for the $hbox{Al}_{2}hbox{O}_{3}/hbox{SiN}_{x}$ device is two to three orders of magnitude lower than that for the $hbox{Al}_{2} hbox{O}_{3}$ device. The mobility fluctuation is the dominant LFN mechanism in both devices, but the noise from the source/drain contacts becomes comparable to the intrinsic channel noise as the gate overdrive voltage increases in $hbox{Al}_{2}hbox{O}_{3}/hbox{SiN}_{x}$ devices. The $hbox{SiN}_{x}$ interfacial layer is considered to be very effective in reducing LFN by suppressing the remote phonon scattering from the $hbox{Al}_{2}hbox{O}_{3}$ dielectric. Hooge's parameter is extracted to $sim !!hbox{6.0} times hbox{10}^{-3}$ in $hbox{Al}_{2}hbox{O}_{3}/hbox{SiN}_{x}$ devices.