Evaluation of Qbd for electrons tunneling fromthe Si/SiO2 interface compared to electron tunneling from thepoly-Si/SiO2 interface

Electrical time-to-breakdown (TTB) measurements have shown the charge to breakdown Q_bd of gate oxide capacitors fabricated on n-type well (n-well) substrates always to be higher than that of capacitors on p-type well (p-well) substrates on the same wafer when both are biased into accumulation under normal test conditions. Here the authors correlate the higher n-well Q_bd to smooth capacitor oxide/substrate interfaces and minimized grain boundary cusps at the poly-Si gate/oxide interfaces, confirming that Fowler-Nordheim tunneling is the dominant current conduction mechanisms through the oxide. They correlate higher Q_bd to higher barrier height for a given substrate type and observe that the slope of the barrier height versus temperature plot is lower for both p-well and n-well cases with electrons tunneling from the silicon substrate. This is attributed to surface roughness at the poly-Si gate/SiO₂ interface. A poly-Si gate deposition and annealing process with clean, smooth oxide/substrate interfaces will improve the p-well breakdown characteristics and allow higher Q_bd to be achieved     

5 GHz high-temperature-superconductor resonators with high Q and low power dependence up to 90 K

The authors have fabricated high-temperature superconducting films made of TlBaCaCuO (2212) and YBaCuO (123) by postdeposition annealing techniques on (100) LaAlO₃ substrates. These films, especially the TlBaCaCuO(2212), exhibit high temperature operation, high Q (low surface resistance), and low power dependence. Both types of films have measured surface resistances which are better than 1/10 that of copper to 20 GHz. Microstrip resonators with a fundamental resonance frequency of 5 GHz were fabricated from these materials. The performance of the best resonator at 90 K (loaded Q>20000 at 5 GHz) was 50 times better than an analogous copper resonator (also measured at 90 K) and can handle more than 10 W of peak power in the resonator with only a small degradation of the Q. In addition, the shift of the resonator frequencies with temperature was fit to a two-fluid model     

Measurement of Raman gain coefficients of hydrogen, deuterium, andmethane

The authors report measurements of the absolute Raman gain of H ₂ Q(1), D₂ Q(2), and CH₄ (ν₁) at 532 nm using a Raman oscillator/amplifier arrangement. Experimentally determined steady-state gain coefficients are compared to values calculated using spectroscopic data. The dependence of the observed gain on the pressure mismatch in a Raman oscillator/amplifier system is also investigated. The measured values for hydrogen and methane are found to agree with calculated values and with the results of previous measurements. For deuterium the authors find a value of 0.45 cm/GW, which also agrees reasonably well with the calculated value     

Yttrium oxide/silicon dioxide: a new dielectric structure forVLSI/ULSI circuits

Electrical characteristics of Al/yttrium oxide (~260 Å)/silicon dioxide (~40 Å)/Si and Al/yttrium oxide (~260 Å)/Si structures are described. The Al/Y₂O₃/SiO₂/Si (MYOS) and Al/Y₂ O₃/Si (MYS) capacitors show very well-behaved I-V characteristics with leakage current density <10^-10 A/cm² at 5 V. High-frequency C- V and quasistatic C-V characteristics show very little hysteresis for bias ramp rate ranging from 10 to 100 mV/s. The average interface charge density (Q_f+Q _it) is ~6×10¹¹/cm² and interface state density D_it is ~10¹¹ cm^-2-eV^-1 near the middle of the bandgap of silicon. The accumulation capacitance of this dielectric does not show an appreciable frequency dependence for frequencies varying from 10 kHz to 10 MHz. These electrical characteristics and dielectric constant of ~17-20 for yttrium oxide on SiO₂/Si make it a variable dielectric for DRAM storage capacitors and for decoupling capacitors for on-chip and off-chip applications     

Measurements and modeling of the n-channel MOSFET inversion layermobility and device characteristics in the temperature range 60-300 K

Discussed is the use of the high-frequency split C-V method to measure accurately the effective mobility of the n-channel MOS transistor as a function of temperature, bulk charge Q _b, and inversion layer charge Q_i. The experimental data for Q_b and Q_i were verified by comparison with the results of numerical simulation. The results of the measurements were used to develop the mobility model, which is accurate in the 60-300 K temperature range. The proposed mobility model incorporates Coulombic, lattice, and surface roughness scattering modes and generalizes the previous model, which was limited to low-temperature operation of the MOSFET. The deviation from the universal (for different back biases) μ(E_eff) dependence, which becomes more pronounced at low temperatures and low E_eff, is included in the model and can be associated with the Coulomb scattering mechanism. The proposed model is verified by comparison of experimental data and simulated MOSFET I-V characteristics for different temperatures     

More on the decoder error probability for Reed-Solomon codes

A combinatorial technique similar to the principle of inclusion and exclusion is used to obtain an exact formula for P_E (u), the decoder error probability for Reed-Solomon codes. The P_E(u) for the (255, 223) Reed-Solomon code used by NASA and for the (31, 15) Reed-Solomon code (JTIDS code) are calculated using the exact formula and are observed to approach the Qs of the codes rapidly as u gets large. An upper bound for the expression |P_E(u)/ Q-1| is derived and shown to decrease nearly exponentially as u increases     

The calculation of the probability of detection and the generalizedMarcum Q-function

A highly reliable, accurate, and efficient method of calculating the probability of detection, P_N(X,Y ), for N incoherently integrated samples, where X is the constant received signal-to-noise ratio of a single pulse and Y is the normalized threshold level, is presented. The useful range of parameters easily exceeds most needs. On a VAX/11 computer with double precision calculations, better than 13-place absolute accuracy is normally achieved. There is a gradual loss of accuracy with increasing parameter values. For example, for N=10⁹, and with both NX and Y near 10⁷, the accuracy can drop to ten places. The function P_N(X,Y ) can be equated to the generalized Marcum Q-function, Q_m(α,β). The corresponding limits on α and β are roughly 4500 for the 13-place accuracy and 60000 for ultimate (INTEGER×4) limit     

A self-injection locked, Q-switched, line-narrowed Ti:Al2O3 laser

Line-narrowing, Q-switched, and self-injection locking are studied independently and as a system. Line narrowing is shown both theoretically and experimentally to depend on the inverse square root of the pulse evolution time interval. Q switching of the Ti:Al₂O₃ laser is demonstrated and the laser output energy as a function of the Q-switch delay is investigated. Self-injection is demonstrated and the operation of the laser is explored as a function of loss and the Q-switch delay. Self-injection locking is demonstrated and the performance as a function of the Q-switch delay is determined     

An EMQ-switched CO2 laser as a pump source for afar-infrared laser with a high peak power and a high repetitionrate

A modified current pulsed Q (EMQ)-switched CO₂ laser which is Q-switched by a mechanical beam chopper in combination with a pulsed discharge current is discussed. The laser produces a very stable output with a peak power greater than 1 kW at a repetition rate of 1000 p.p.s. for all transitions in the P and R branches of the CO₂ spectrum. A CH₃F laser pumped by the EMQ-switched laser produces 496 μm radiation in a 6.5 W peak, 100 ns pulses at 500 p.p.s. in the lowest loss EH₁₁ mode     

A low-loss bandpass filter using electrically coupled high-Q TM01δ dielectric rod resonators

For a TM_01δ mode dielectric rod resonator placed coaxially in a TM₀₁ cutoff circular waveguide, characteristics such as the resonant frequency, its temperature coefficient, the unloaded Q, and the other resonances are discussed on the bases of accurate calculations using the mode-matching method. The results show that this resonator compares favorably with a conventional TE_01δ mode dielectric resonator, particularly for realization of a high unloaded Q. Analytical results also verify that interresonator coupling between these two resonators can be expressed equivalently by a capacitively coupled LC resonant circuit. A four-stage Chebyshev filter having a ripple of 0.035 dB and an equiripple bandwidth of 27 MHz at a center frequency of 11.958 GHz was fabricated using these resonators. Its insertion loss is 0.5 dB, which corresponds to an unloaded Q of 17000, and no spurious response appears in the frequency range below 17 GHz     

A simple scheme for unity power-factor rectification for highfrequency AC buses

A simple scheme is proposed for offline unity power factor rectification for high-frequency AC buses (20 kHz). A bandpass filter of the series-resonant type, centered at the line frequency, is inserted between the line and the full-wave rectified load. The Q=Z ₀/R_L formed by the load and the characteristic impedance of the tank circuit determines the power factor, the boundary between continuous and discontinuous conduction modes, the peak stresses, and the transient response of the rectifier. It is shown that for Q>2/π the rectifier operates in continuous conduction mode and the output voltage is independent of the load. Also, it is shown that for Q>2 the line current is nearly sinusoidal with less than 5% third-harmonic distortion and the power factor is essentially unity. An increase in Q causes an increase in the peak voltages of the tank circuit and a slower transient response of the rectifier circuit. The DC, small-signal, and transient analyses of the rectifier circuit are carried out, and the results are in good agreement with simulation and experimental results     

Dependence of thin-oxide films quality on surface microroughness

The effects of silicon surface microroughness on electrical properties of thin-oxide films, such as breakdown electric field intensity (E_BD) and time-dependent dielectric breakdown (Q_BD), have been studied, where the microroughnesses of silicon and silicon dioxide surfaces are evaluated by the scanning tunneling microscope (STM) and the atomic force microscope (AFM), respectively. An increase of surface microroughness has been confirmed to severely degrade the E_BD and Q_BD characteristics of thin-oxide films with thicknesses of 8-10 nm and to simultaneously decrease channel electron mobility. An increase of surface microroughness has been demonstrated to originate mainly from wet chemical cleaning processing based on the RCA cleaning concept, particularly the ammonium-hydrogen-peroxide cleaning step. In order to keep the surface microroughness at an initial level, the content ratio of NH₄OH/H₂O₂/H₂ O solution has been set at 0.05:1:5 and the room-temperature DI water rinsing has been introduced right after the NH₄OH/H₂O₂/H₂O cleaning step in conventional RCA cleaning procedure     

Output energy characteristics of optimally pumped rotating mirrorQ-switch lasers

The author develops a simple analytical formula for the key laser resonator and Q-switch parameters of an optimally pumped rotating mirror Q-switch laser. The analytical expression developed relates the maximum attainable single pulse output energy to the laser parameters such as rotating mirror speed, output mirror reflectivity, length of the resonator, and the absorption cross section of the laser media on the basis of the experimentally measured mechanical Q-switch loss form. Good agreement between theory and the output performance of a test Nd-glass laser has been demonstrated     

Absolute and relative nonlinear optical coefficients of KDP, KD*P,BaB2O4, LiIO3, MgO:LiNbO3,and KTP measured by phase-matched second-harmonic generation

Both absolute and relative nonlinear optical coefficients of six nonlinear materials measured by second-harmonic generation are discussed. A single-mode, injection-seeded, Q-switched Nd:YAG laser with spatially filtered output was used to generate the 1.064-μm fundamental radiation. The following results were obtained: d₃₆(KD*P)=0.38 pm/V, d₃₆(KD*P)=0.37 pm/V, |d₂₂(BaB ₂O₄)|=2.2 pm/V, d₃₁(LiIO₃ )=-4.1 pm/V, d₃₁(5%MgO:MgO LiNbO₃)=-4.7 pm/V, and d_eff(KTP)=3.2 pm/V. The accuracy of these measurements is estimated to be better than 10%     

Accurate conductor Q-factor of dielectric resonator placed in anMIC environment

The unloaded Q-factor of a dielectric resonator is degraded due to conductor loss when it is placed in an MIC environment. The authors report approximate but quite accurate closed form expressions for the Q-factor due to conductor loss. The results obtained are in good agreement with those of rigorous numerical methods. The effect of geometrical parameters on the useful tuning range of the structure is studied. Finally, an explicit relationship between the resonant frequency sensitivity factors and the conductor Q-factor is derived     

A numerical study of a dielectric disk antenna above groundeddielectric substrate

An antenna made of a dielectric disk with a high permittivity mounted on top of a grounded dielectric substrate of low permittivity is analyzed. A numerical procedure based on surface integral equations, derived from the equivalence principle, is used to compute the natural resonant frequencies for the HEM₁₁ mode from which the radiation Q factor of the antenna is obtained. Then the radiation pattern of the antenna, operating at the resonant frequency evaluated previously, is computed with an electric dipole excitation located within the dielectric substrate under the dielectric disk. The effect of various parameters on the radiation characteristics of the antenna is studied, and presented in the form of diagrams. The low values of the radiation Q, combined with the high values of the dielectric Q and conductor Q, indicate that this antenna promises to be more efficient then the microstrip antenna     

Transient M/M/1 queue variance computation using generalized Q functions

A generalized Q function representation for the transient M/M/1 queue variance is developed. The expression is highly accurate and computationally efficient, and an upper bound on the error is easily calculated. For a Q function relative error of 2×10-¹² using Parl's method, the relative error of the variance is generally less than 10^-9. Average execution time is of the order of 70 ms per point on a VAX 11/750, but faster execution times can be obtained by using larger Q function relative errors     

Electrooptically Q-switched 2.79 μm YSGG:Cr:Er laserwith an intracavity polarizer

Single Q-switched pulses have been generated in YSGG:Cr:Er with a 360-ns-risetime LiNbO₃ electrooptical modulator. It is shown that birefringence losses can be avoided and spiking emission eliminated by placing an additional polarizing LiNbO ₃ prism inside the laser resonator. Reproducible single Q -switched pulses of 200-ns duration have been generated     

Frequency-hopped multiple access communications with coding andside information

The authors consider frequency-hopped spread-spectrum multiple-access communications using M-ary modulation and error-correction coding. The major concerns are multiple-access interference and the network capacity in terms of the number of users that can transmit simultaneously for a given level of codeword error probability. Block coding is studied in detail. The authors first consider the use of Q-ary Reed-Solomon (RS) codes in combination with M-ary modulation with mismatched alphabets so that Q>M. It is shown that the network capacity is drastically reduced in comparison with the system with matched alphabets. As a remedy, the use of matched M-ary BCH codes is proposed as an alternative to mismatched RS codes. It is shown that when the number of users in the system is large, a BCH code outperforms an RS code with a comparable code rate and decoding complexity. The authors consider the use of a robust technique for generation of reliable side information based on a radio-threshold test. They analyze its performance in conjunction with MFSK and error-erasure correction decoding. It is shown that this nonideal ratio-threshold method can increase the network capacity in comparison with the system with perfect side information     

Measured performance at 77 K of superconducting microstripresonators and filters

Results on three types of passive microwave devices fabricated and tested using epitaxial thin films of Tl₂CaBa₂Cu ₂O₈ grown on LaAlO₃ are reported. A microstrip ring resonator with unloaded Q of 2740 at 77 K and 33 GHz is described. A superconducting 4.6 GHz band-reject filter with unloaded Q greater than 15000 when operated at 77 K is reported. In addition, results on a multiple microstrip bandpass filter are presented