High-responsivity high-gain In/sub 0.53/Ga/sub 0.47/As-InP quantum-well infrared photodetectors grown using metal-organic vapor phase epitaxy

We report the growth and fabrication of bound-to-bound In/sub 0.53/Ga/sub 0.47/As-InP quantum-well infrared photodetectors using metal-organic vapor phase epitaxy. These detectors have a peak detection wavelength of 8.5 /spl mu/m. The peak responsivities are extremely large with R/sub pk/=6.9 A/W at bias voltage V/sub b/=3.4 V and temperature T=10 K. These large responsivities arise from large detector gain that was found to be g/sub n/=82 at V/sub b/=3.8 V from dark current noise measurements at T=77 K and g/sub p/=18.4 at V/sub b/=3.4 V from photoresponse data at T=10 K. The background-limited temperature with F/1.2 optics is T/sub BLIP/=65 K for 0相似文献   

Complex Permittivity of GaAs and CdTe at Microwave Frequencies

The microwave dielectric constant and loss tangent of Cr-doped semi-insulatiug GaAs have been measured in the frequency range 2.5-36.0 GHz and the temperature range 300-400 K. The room temperature dielectric constant is 12.95 and the temperature coefficient alpha ( /spl equiv/ epsilon(0)/sup -1/ d epsilon/dT) is 1.6 x 10/sup -4/ /K. The dielectric constant and loss tangent of CdTe have been measured as functions of temperature at 15.95 GHz. The room temperature dielectric constant is 10.39 /spl plusmn/ 0.04 and the temperature coefficient alpha is 2.5 x 10/sup -4/ /K.     

Very high density RF MIM capacitors (17 fF//spl mu/m/sup 2/) using high-/spl kappa/ Al/sub 2/O/sub 3/ doped Ta/sub 2/O/sub 5/ dielectrics

Using high-/spl kappa/ Al/sub 2/O/sub 3/ doped Ta/sub 2/O/sub 5/ dielectric, we have obtained record high MIM capacitance density of 17 fF//spl mu/m/sup 2/ at 100 kHz, small 5% capacitance reduction to RF frequency range, and low leakage current density of 8.9/spl times/10/sup -7/ A/cm/sup 2/. In combination of both high capacitor density and low leakage current density, a very low leakage current of 5.2/spl times/10/sup -12/ A is calculated for a typical large 10 pF capacitor used in RF IC that is even smaller than that of a deep sub-/spl mu/m MOSFET. This very high capacitance density with good MIM capacitor characteristics can significantly reduce the chip size of RF ICs.     

Characterization of the temperature sensitivity of gain and recombination mechanisms in 1.3-/spl mu/m AlGaInAs MQW lasers

The potential of 1.3-/spl mu/m AlGaInAs multiple quantum-well (MQW) laser diodes for uncooled operation in high-speed optical communication systems is experimentally evaluated by characterizing the temperature dependence of key parameters such as the threshold current, transparency current density, optical gain and carrier lifetime. Detailed measurements performed in the 20/spl deg/C-100/spl deg/C temperature range indicate a localized T/sub 0/ value of 68 K at 98/spl deg/C for a device with a 2.8 /spl mu/m ridge width and 700-/spl mu/m cavity length. The transparency current density is measured for temperatures from 20/spl deg/C to 60/spl deg/C and found to increase at a rate of 7.7 A/spl middot/cm/sup -2//spl middot/ /spl deg/C/sup -1/. Optical gain characterizations show that the peak modal gain at threshold is independent of temperature, whereas the differential gain decreases linearly with temperature at a rate of 3/spl times/10/sup -4/ A/sup -1//spl middot//spl deg/C/sup -1/. The differential carrier lifetime is determined from electrical impedance measurements and found to decrease with temperature. From the measured carrier lifetime we derive the monomolecular ( A), radiative (B), and nonradiative Auger (C) recombination coefficients and determine their temperature dependence in the 20/spl deg/C-80/spl deg/C range. Our study shows that A is temperature independent, B decreases with temperature, and C exhibits a less pronounced increase with temperature. The experimental observations are discussed and compared with theoretical predictions and measurements performed on other material systems.     

A high-density MIM capacitor (13 fF//spl mu/m/sup 2/) using ALD HfO/sub 2/ dielectrics

Metal-insulator-metal (MIM) capacitors with different HfO/sub 2/ thickness have been investigated. The results show that both the capacitance density and voltage coefficients of capacitance (VCCs) increase with decreasing HfO/sub 2/ thickness. In addition, it is found that the VCCs decrease logarithmically with increasing thickness. Furthermore, the MIM capacitor with 10-nm HfO/sub 2/ shows a record high capacitance density of 13 fF//spl mu/m/sup 2/ and a VCC of 607 ppm/V, which can meet the requirement of the International Technology Roadmap for Semiconductors. It can also provide a low leakage current of 5.95 /spl times/ 10/sup -8/A/cm/sup 2/ at room temperature at 1 V, low tangent values below 0.05, and a small frequency dependence. These results indicate that the devices are suitable for use in silicon integrated circuit applications.     

Room-temperature InAsSb photovoltaic detectors for mid-infrared applications

Novel noncryogenic InAsSb photovoltaic detectors grown by molecular beam epitaxy are proposed and demonstrated. The quaternary alloy In/sub 0.88/Al/sub 0.12/As/sub 0.80/Sb/sub 0.20/ is introduced as a wide bandgap barrier layer lattice matched to the GaSb substrate. The valence band edge of In/sub 0.88/Al/sub 0.12/As/sub 0.80/Sb/sub 0.20/ nearly matches with InAs/sub 0.91/Sb/sub 0.09/, leading to more efficient transport of photogenerated holes. The resulting mid-infrared photovoltaic detector exhibits a 50% cutoff wavelength of 4.31 /spl mu/m and a peak responsivity of 0.84 A/W at room temperature. High Johnson-noise-limited detectivity (D/sup */) of 2.6/spl times/10/sup 9/ cm/spl middot/Hz/sup 1/2//W at 4.0 /spl mu/m, and 4.2/spl times/10/sup 10/ cm/spl middot/Hz/sup 1/2//W at 3.7 /spl mu/m are achieved at 300 K and 230 K, respectively.     

Low-frequency noise in submicrometer MOSFETs with HfO/sub 2/, HfO/sub 2//Al/sub 2/O/sub 3/ and HfAlO/sub x/ gate stacks

Low-frequency noise measurements were performed on p- and n-channel MOSFETs with HfO/sub 2/, HfAlO/sub x/ and HfO/sub 2//Al/sub 2/O/sub 3/ as the gate dielectric materials. The gate length varied from 0.135 to 0.36 /spl mu/m with 10.02 /spl mu/m gate width. The equivalent oxide thicknesses were: HfO/sub 2/ 23 /spl Aring/, HfAlO/sub x/ 28.5 /spl Aring/ and HfO/sub 2//Al/sub 2/O/sub 3/ 33 /spl Aring/. In addition to the core structures with only about 10 /spl Aring/ of oxide between the high-/spl kappa/ dielectric and silicon substrate, there were "double-gate oxide" structures where an interfacial oxide layer of 40 /spl Aring/ was grown between the high-/spl kappa/ dielectric and Si. DC analysis showed low gate leakage currents in the order of 10/sup -12/A(2-5/spl times/10/sup -5/ A/cm/sup 2/) for the devices and, in general, yielded higher threshold voltages and lower mobility values when compared to the corresponding SiO/sub 2/ devices. The unified number-mobility fluctuation model was used to account for the observed 1/f noise and to extract the oxide trap density, which ranged from 1.8/spl times/10/sup 17/ cm/sup -3/eV/sup -1/ to 1.3/spl times/10/sup 19/ cm/sup -3/eV/sup -1/, somewhat higher compared to conventional SiO/sub 2/ MOSFETs with the similar device dimensions. There was no evidence of single electron switching events or random telegraph signals. The aim of this paper is to present a general discussion on low-frequency noise characteristics of the three different high-/spl kappa//gate stacks, relative comparison among them and to the Si--SiO/sub 2/ system.     

Analysis of transit times and minority carrier mobility in n-p-n 4H-SiC bipolar junction transistors

An analysis of the transit times and minority carrier mobility in n-p-n 4H-SiC RF bipolar junction transistors is presented. These parameters were extracted from small signal RF measurements on 4H-SiC RF transistors with three different base thicknesses: 100, 140, and 200 nm. The study shows that the room temperature minority carrier electron mobility is 215 cm/sup 2//V/spl middot/s for a base Al doping of N/sub B/=4/spl times/10/sup 18/ cm/sup -3/. The analysis reveals that the collector charging time /spl tau//sub C/ and the parasitic charging time /spl tau//sub P/ from the capacitance between metal pads and the underlying collector region have a significant effect on the transistors RF performance. The calculated RF gain is in good agreement with the measured results.     

High-performance MIM capacitor using ALD high-k HfO/sub 2/-Al/sub 2/O/sub 3/ laminate dielectrics

For the first time, we successfully fabricated and demonstrated high performance metal-insulator-metal (MIM) capacitors with HfO/sub 2/-Al/sub 2/O/sub 3/ laminate dielectric using atomic layer deposition (ALD) technique. Our data indicates that the laminate MIM capacitor can provide high capacitance density of 12.8 fF//spl mu/m/sup 2/ from 10 kHz up to 20 GHz, very low leakage current of 3.2 /spl times/ 10/sup -8/ A/cm/sup 2/ at 3.3 V, small linear voltage coefficient of capacitance of 240 ppm/V together with quadratic one of 1830 ppm/V/sup 2/, temperature coefficient of capacitance of 182 ppm//spl deg/C, and high breakdown field of /spl sim/6 MV/cm as well as promising reliability. As a result, the HfO/sub 2/-Al/sub 2/O/sub 3/ laminate is a very promising candidate for next generation MIM capacitor for radio frequency and mixed signal integrated circuit applications.     

Analysis and Evaluation of a Method of Measuring the Complex Permittivity and Permeability Microwave Insulators

Theory and experimental results are presented to show the possibility of using a resonant post technique for characterizing dielectric and magnetic materials at microwave frequencies. Results of the temperature dependence of the relative dielectric constant of nonmagnetic materials with /spl epsilon//sub r/, varying from 4 to 60 are presented and also loss tangent measurements at room temperature. The complex permittivity and permeability of a number of garnet materials has also been measured with 4/spl pi//spl gamma/M/sub s/ / /spl omega/ varying from 0.25 to 0.8. The measured real part of the permeability is in good agreement with the theoretical predictions of Schlomann and the imaginary part of the permeability agrees with measurements by Green et al. on similar materials.     

Full characterization of packaged Er-Yb-codoped phosphate glass waveguides

We present a procedure for the characterization of packaged Er-Yb-codoped phosphate glass waveguides. The procedure is based on precise measurements of the output optical powers when the waveguide is diode-laser pumped at 980 nm. The dependence of these optical powers on the input pump power is then fitted to the results from a numerical model that describes in detail the propagation of the optical powers inside the waveguide. The best fit is obtained for the following parameters: the signal wavelength scattering losses are /spl alpha/(1534)=8.3/spl times/10/sup -2/ dB/cm, the Yb/sup 3+/ absorption and emission cross sections (/spl ap/980 nm) are 5.4/spl times/10/sup -25/ m/sup 2/ and 7.0/spl times/10/sup -25/ m/sup 2/, the Er/sup 3+/ absorption and emission cross sections (/spl ap/980 nm) are 1.6/spl times/10/sup -25/ m/sup 2/ and 1.2/spl times/10/sup -25/ m/sup 2/, the Yb/sup 3+/--Er/sup 3+/ energy-transfer coefficient is 1.8/spl times/10/sup -23/ m/sup 3//s and the cooperative-upconversion coefficient is 8/spl times/10/sup -25/ m/sup 3//s. An approximate method is introduced that allows the determination of the absorption and emission cross section distributions for the erbium /sup 4/I/sub 13/2//spl hArr//sup 4/I/sub 15/2/ transition from the amplified spontaneous emission power spectrum.     

Low-frequency noise in submicrometer MOSFETs with HfO/sub 2/, HfO/sub 2//Al/sub 2/O/sub 3/ and HfAlO/sub x/ gate stacks

Low-frequency noise measurements were performed on p- and n-channel MOSFETs with HfO/sub 2/, HfAlO/sub x/ and HfO/sub 2//Al/sub 2/O/sub 3/ as the gate dielectric materials. The gate length varied from 0.135 to 0.36 /spl mu/m with 10.02 /spl mu/m gate width. The equivalent oxide thicknesses were: HfO/sub 2/ 23 /spl Aring/, HfAlO/sub x/ 28.5 /spl Aring/ and HfO/sub 2//Al/sub 2/O/sub 3/ 33 /spl Aring/. In addition to the core structures with only about 10 /spl Aring/ of oxide between the high-K dielectric and silicon substrate, there were "double-gate oxide" structures where an interfacial oxide layer of 40 /spl Aring/ was grown between the high-K dielectric and Si. DC analysis showed low gate leakage currents in the order of 10/sup -12/ A(2-5 /spl times/ 10/sup -5/ A/cm/sup 2/) for the devices and, in general, yielded higher threshold voltages and lower mobility values when compared to the corresponding SiO/sub 2/ devices. The unified number-mobility fluctuation model was used to account for the observed 1/f noise and to extract the oxide trap density, which ranged from 1.8 /spl times/ 10/sup 17/ cm/sup -3/ eV/sup -1/ to 1, 3 /spl times/ 10/sup 19/ cm/sup -3/ eV/sup -1/ somewhat higher compared to conventional SiO/sub 2/ MOSFETs with the similar device dimensions. There was no evidence of single electron switching events or random telegraph signals. The aim of this paper is to present a general discussion on low-frequency noise characteristics of the three different high-K/gate stacks, relative comparison among them and to the Si-SiO/sub 2/ system.     

Si interlayer passivation on germanium MOS capacitors with high-/spl kappa/ dielectric and metal gate

We have demonstrated the advantages of silicon interlayer passivation on germanium MOS devices, with CVD HfO/sub 2/ as the high-/spl kappa/ dielectric and PVD TaN as the gate electrode. A silicon interlayer between a germanium substrate and a high-/spl kappa/ dielectric, deposited using SiH/sub 4/ gas at 580/spl deg/C, significantly improved the electrical characteristics of germanium devices in terms of low D/sub it/ (7/spl times/10/sup 10//cm/sup 2/-eV), less C- V hysteresis and frequency dispersion. Low leakage current density of 5/spl times/10/sup -7/ A/cm/sup 2/ at 1 V bias with EOT of 12.4 /spl Aring/ was achieved. Post-metallization annealing caused continuing V/sub fb/ positive shift and J/sub g/ increase with increased annealing temperature, which was possibly attributed to Ge diffusion into the dielectric during annealing.     

Dissipative Parameters in Ferrites and Insertion Losses in Waveguide Y-Circulators Below Resonance

Extensive microwave loss measurements have been performed at frequencies from 1.3 to 11 GHz on below-resonance waveguide Y circulators loaded with a wide variety of ferrite and garnet compositions. Dissipative internal and external magnetic parameters have been measured on the same compositions. Also, dielectric loss measurements have been carried out. Two classes have been distinguished, defined by the following conditions: /spl omega//sub M/ / /spl omega/ /spl les/0.8 and 0.85 /spl les//spl omega//sub M/ / /spl omega/ /spl les/1.05. It is inferred that the (insertion loss) IL of such devices is independent of /spl Delta/H and mainly depends on the internal dissipative susceptibility x/sub i/" and on the dielectric loss tan /spl delta/. The relation of the IL versus x/sub i/" and tan /spl delta/ in the case /spl omega//sub M/ / /spl omega/ /spl les/0.8 is independent of frequency and given by the semiempirical equation IL= 10 log/sub 10/ (1-2.85 x/sub i/" - 1.60 tan /spl delta/ - 0.017)/sup -1/.     

10-kV, 123-m/spl Omega//spl middot/cm/sup 2/ 4H-SiC power DMOSFETs

10-kV, 123-m/spl Omega//spl middot/cm/sup 2/ power DMOSFETs in 4H-SiC are demonstrated. A 42% reduction in R/sub on,sp/, compared to a previously reported value, was achieved by using an 8 /spl times/ 10/sup 14/ cm/sup -3/ doped, 85-/spl mu/m-thick drift epilayer. An effective channel mobility of 22 cm/sup 2//Vs was measured from a test MOSFET. A specific on-resistance of 123 m/spl Omega//spl middot/cm/sup 2/ were measured with a gate bias of 18 V, which corresponds to an E/sub ox/ of 3 MV/cm. A leakage current of 197 /spl mu/A was measured at a drain bias of 10 kV from a 4H-SiC DMOSFET with an active area of 4.24 /spl times/ 10/sup -3/ cm/sup 2/. A switching time of 100 ns was measured in 4.6-kV, 1.3-A switching measurements. This shows that the 4H-SiC power DMOSFETS are ideal for high-voltage, high-speed switching applications.     

MIM capacitors using atomic-layer-deposited high-/spl kappa/ (HfO/sub 2/)/sub 1-x/(Al/sub 2/O/sub 3/)/sub x/ dielectrics

Metal-insulator-metal (MIM) capacitors with (HfO/sub 2/)/sub 1-x/(Al/sub 2/O/sub 3/)/sub x/ high-/spl kappa/ dielectric films were investigated for the first time. The results show that both the capacitance density and voltage/temperature coefficients of capacitance (VCC/TCC) values decrease with increasing Al/sub 2/O/sub 3/ mole fraction. It was demonstrated that the (HfO/sub 2/)/sub 1-x/(Al/sub 2/O/sub 3/)/sub x/ MIM capacitor with an Al/sub 2/O/sub 3/ mole fraction of 0.14 is optimized. It provides a high capacitance density (3.5 fF//spl mu/m/sup 2/) and low VCC values (/spl sim/140 ppm/V/sup 2/) at the same time. In addition, small frequency dependence, low loss tangent, and low leakage current are obtained. Also, no electrical degradation was observed for (HfO/sub 2/)/sub 1-x/(Al/sub 2/O/sub 3/)/sub x/ MIM capacitors after N/sub 2/ annealing at 400/spl deg/C. These results show that the (HfO/sub 2/)/sub 0.86/(Al/sub 2/O/sub 3/)/sub 0.14/ MIM capacitor is very suitable for capacitor applications within the thermal budget of the back end of line process.     

Timing-synchronization analysis for IEEE 802.11a wireless LANs in frequency-nonselective Rician fading environments

This paper derives and computes the probability of synchronization failure P/sub fail/ for IEEE 802.11a wireless LANs on frequency-flat Rician fading channels. For a frequency offset within /spl plusmn/232 kHz, it is shown that its effect on the synchronization performance is minor. The E/sub ds//N/sub 0/ ratios required to achieve P/sub fail/=10/sup -3/ and 10/sup -4/ are computed, where E/sub ds/ is the data-symbol energy. We find that E/sub ds//N/sub 0/ ratios over 20 dB are generally required for channels with Rician factors K/spl les/6 dB. In particular, E/sub ds//N/sub 0/ ratios that yield P/sub fail/=10/sup -4/ exceed 30 dB for K/spl les/4 dB.     

A resonant tunneling quantum-dot infrared photodetector

A novel device-resonant tunneling quantum-dot infrared photodetector-has been investigated theoretically and experimentally. In this device, the transport of dark current and photocurrent are separated by the incorporation of a double barrier resonant tunnel heterostructure with each quantum-dot layer of the device. The devices with In/sub 0.4/Ga/sub 0.6/As-GaAs quantum dots are grown by molecular beam epitaxy. We have characterized devices designed for /spl sim/6 /spl mu/m response, and the devices also exhibit a strong photoresponse peak at /spl sim/17 /spl mu/m at 300 K due to transitions from the dot excited states. The dark currents in the tunnel devices are almost two orders of magnitude smaller than those in conventional devices. Measured values of J/sub dark/ are 1.6/spl times/10/sup -8/ A/cm/sup 2/ at 80 K and 1.55 A/cm/sup 2/ at 300 K for 1-V applied bias. Measured values of peak responsivity and specific detectivity D/sup */ are 0.063 A/W and 2.4/spl times/10/sup 10/ cm/spl middot/Hz/sup 1/2//W, respectively, under a bias of 2 V, at 80 K for the 6-/spl mu/m response. For the 17-/spl mu/m response, the measured values of peak responsivity and detectivity at 300 K are 0.032 A/W and 8.6/spl times/10/sup 6/ cm/spl middot/Hz/sup 1/2//W under 1 V bias.     

InAlN/GaN HEMTs: a first insight into technological optimization

High-electron mobility transistors (HEMTs) were fabricated from heterostructures consisting of undoped In/sub 0.2/Al/sub 0.8/N barrier and GaN channel layers grown by metal-organic vapor phase epitaxy on (0001) sapphire substrates. The polarization-induced two-dimensional electron gas (2DEG) density and mobility at the In/sub 0.2/Al/sub 0.8/N/GaN heterojunction were 2/spl times/10/sup 13/ cm/sup -2/ and 260 cm/sup 2/V/sup -1/s/sup -1/, respectively. A tradeoff was determined for the annealing temperature of Ti/Al/Ni/Au ohmic contacts in order to achieve a low contact resistance (/spl rho//sub C/=2.4/spl times/10/sup -5/ /spl Omega//spl middot/cm/sup 2/) without degradation of the channels sheet resistance. Schottky barrier heights were 0.63 and 0.84 eV for Ni- and Pt-based contacts, respectively. The obtained dc parameters of 1-/spl mu/m gate-length HEMT were 0.64 A/mm drain current at V/sub GS/=3 V and 122 mS/mm transconductance, respectively. An HEMT analytical model was used to identify the effects of various material and device parameters on the InAlN/GaN HEMT performance. It is concluded that the increase in the channel mobility is urgently needed in order to benefit from the high 2DEG density.     

Demonstration of 1789 V, 6.68 m/spl Omega/ /spl middot/ cm/sup 2/ 4H-SiC merged-PiN-Schottky diodes

The design, fabrication and characterisation of a high performance 4H-SiC diode of 1789 V-6.6 A with a low differential specific-on resistance (R/sub SP/spl I.bar/ON/) of 6.68 m/spl Omega/ /spl middot/ cm/sup 2/, based on a 10.3 /spl mu/m 4H-SiC blocking layer doped to 6.6/spl times/10/sup 15/ cm/sup -3/, is reported. The corresponding figure-of-merit of V/sub B//sup 2//R/sub SP/spl I.bar/ON/ for this diode is 479 MW/cm/sup 2/, which substantially surpasses previous records for all other MPS diodes.