Preparation of ferroelectric Ba(Ti/sub 0.85/Sn/sub 0.15/)O/sub 3/ thin films by metal-organic decomposition

Ferroelectric Ba(Ti/sub 0.85/Sn/sub 0.15/)O/sub 3/ (BTS/sub 15/) thin film is newly prepared on the Pt/Ti/SiO/sub 2//Si substrate by metal-organic decomposition. The firing condition is determined by thermogravimetric and differential thermal analysis. The BTS/sub 15/ thin film with a flat surface and uniform thickness is obtained by spin coating in N/sub 2/ atmosphere that avoids moisture. The BTS/sub 15/ film has a perovskite phase and a preferential [110] texture. It is also found that the crystalline structure is cubic at 24/spl deg/C with a lattice constant of 4.01 /spl Aring/, and a grain size of about 30 nm was estimated by Scherrer equation and SEM image. From P-E hysteresis loop at 20/spl deg/C, the polarization at E=0 and the electric field at P=0 are found to be 1.07 /spl mu/C/cm/sup 2/ and 24.0 kV/cm, respectively. It is observed that the dielectric constant decreases monotonously from about 830 to 630 with increasing temperature ranging from 20/spl deg/C to 50/spl deg/C. Finally, it is found that the BTS/sub 15/ thin film shows a sufficient ferroelectricity and is an attractive material for functional ferroelectric devices, such as thermal-type infrared sensors.     

Fabrication of resonant-tunneling diodes by Sb surfactant modified growth of Si films on CaF/sub 2//Si

Molecular beam epitaxy growth of Si thin films on CaF/sub 2//Si(111) substrates has been studied. A surfactant-modified solid-phase epitaxy method, where the room temperature Si deposition was followed by annealing under Sb flux, resulted in a continuous, smooth epitaxial crystalline Si film with a sharp (/spl radic/3/spl times//spl radic/3)R30/spl deg/ reconstruction and a surface roughness of 0.15-nm rms for a 2.8-nm Si thin film. This growth technique was used to fabricate CaF/sub 2//Si/CaF/sub 2/ double-barrier resonant tunneling diodes in SiO/sub 2/ windows patterned on Si(111) substrates. A negative differential resistance (NDR) peak was found at /spl sim/0.35 V at 77 K, and the current density at the NDR peak was estimated to be 3-4 orders of magnitude higher than in earlier reports.     

热极化和电晕极化铁电PVDF薄膜的成分和结构

用高分辨率X-射线光电子能谱（XPS）研究了热极化和电晕极化的PVDF薄膜的成分和结构的变化。结果表明：PVDF薄膜的热极化和电晕极化反应过程和机理不同。在热极化过程中.高温强电场作用使PVDF薄膜产生了少量的F^-自由基,继而产生HF,形成了新C=C键：怛是,在电晕极化过程中荷能粒子使PVDF产生了H^＋自由基。热极...     

Effects of remanent field on an elliptical flaw and a crack in a poled piezoelectric ceramic

Commonly used piezoelectric ceramics such as PZT and PLZT are polarized ferroelectric polycrystals. After poling, remanent strains and a remanent polarization exist in a ceramic material. Remanent field can affect the electroelastic field and consequently plays a critical role in fracture of poled ceramics. Based on a linear constitutive law, the electroelastic field and the energy release rate of an elliptical cavity (or a crack) in a poled piezoelectric are re-examined in this study by including the effects of remanent field. It is noted that the remanent field generally has a minor effect on the stress field and a pronounced effect on the electric field at the apex of the major axis of an elliptical flaw. When the permittivity of the cavity is small, the effect of remanent polarization is similar to that of a very strong electric field applied along the poling direction. However, for the case of a conducting flaw, the remanent field does not influence the electroelastic field and energy release rate. Energy release rate of a flaw in a poled ferroelectric ceramic with and without the remanent polarization is generally different.     

Recent developments in high curie temperature perovskite single crystals

The temperature behavior of various relaxor-PT piezoelectric single crystals was investigated. Owing to a strongly-curved morphotropic phase boundary, the usage temperature of these perovskite single crystals is limited by T/sub R-T/- the rhombohedral to tetragonal phase transformation temperature - which occurs at the significantly lower temperatures than the Curie temperature T/sub c/. Attempts to modify the temperature usage range of Pb(Zn/sub 1/3/Nb/sub 2/3/)O/sub 3/-PbTiO/sub 3/ (PZNT) and Pb(Mg/sub 1/3/Nb/sub 2/3/)O/sub 3/-PbTiO/sub 3/ (PMNT) rhombohedral crystals (T/sub c/ /spl sim/ 150-170/spl deg/C, T/sub R-T/ /spl sim/ 60-120/spl deg/C) using minor dopant modifications were limited, with little success. Of significant potential are crystals near the morphotropic phase boundary in the Pb(Yb/sub 1/2/Nb/sub 1/2/)O/sub 3/-PbTiO/sub 3/ (PYNT) system, with a T/sub c/ > 330/spl deg/C, even though T/sub R-T/ was found to be only half the value at /spl sim/160/spl deg/C. Single crystals in the novel BiScO/sub 3/-PbTiO/sub 3/ system offer significantly higher T/sub c/s > 400/spl deg/C, while exhibiting electromechanical coupling coefficients k/sub 33/ > 90% being nearly constant till the T/sub R-T/ temperature around 350/spl deg/C, which greatly increases the temperature range for transducer applications.     

Standardized evaluation of chemical compositions of LiTaO3 single crystals for SAW devices using the LFB ultrasonic material characterization system

The line-focus-beam ultrasonic material characterization (LIFB-UMC) system is applied to compare and evaluate tolerances provided independently for the Curie temperature T/sub C/ and lattice constant /spl alpha/ to evaluate commercial LiTaO/sub 3/ single crystals by measuring the Rayleigh-type leaky surface acoustic wave (LSAW) velocities V/sub LSAW/. The relationships between VLSAW, and T/sub C/ and /spl alpha/ measured by individual manufacturers were obtained experimentally using 42/spl deg/YX-LiTaO/sub 3/ wafers as specimens from three crystal manufacturers. In addition, the relationship between VLSAW and SH-type SAW velocities V/sub SAW/ that are actually used for the SAW device wafers was obtained through calculations, using the chemical composition dependences of the acoustical physical constants for LiTaO/sub 3/ crystals reported previously. The result of a comparison between the T/sub C/ tolerance of /spl plusmn/3/spl deg/C and the /spl alpha/ tolerance of /spl plusmn/0.00002 nm through the common scale of VLSAW or VSAW demonstrated that the /spl alpha/ tolerance is 1.6 times larger than the T/sub C/ tolerance. Furthermore, we performed a standardized comparison of statistical data of T/sub C/ and /spl alpha/ for LiTaO/sub 3/ crystals grown by two manufacturers during 1999 and 2000, using VLSAW. The results clarified the differences of the average chemical compositions and of the chemical composition distributions among the crystal ingots between the two manufacturers. A guideline for the standardized evaluation procedure has been established for the SAW-device wafer specifications by the LFB-UMC system.     

Enhanced catalytic activity of ultrathin CuO islands on SnO/sub 2/ films for fast response H/sub 2/S gas sensors

H/sub 2/S gas-sensing properties of a novel SnO/sub 2/-CuO structure consisting of ultrathin (/spl sim/10 nm) CuO dotted islands (600 /spl mu/m diameter) on 120-nm thick, sputtered SnO/sub 2/ film are compared with a pure SnO/sub 2/ and a SnO/sub 2/-CuO bilayer sensor. The SnO/sub 2/-CuO-dotted sensor exhibited a high sensitivity of 7.3/spl times/10/sup 3/ at a low operating temperature of 150/spl deg/C. A fast response time of 14 s for 20 ppm of H/sub 2/S gas and a recovery time of 118 s under flowing air have been measured. The electronic interaction due to modulation of the space charge regions between the distributed p-type CuO islands on the n-type SnO/sub 2/ thin-film surface and the presence of adsorbed oxygen on the SnO/sub 2/ support have been analyzed. Dissociated hydrogen available from the CuO-H/sub 2/S interaction spills over and its chemical interaction with the adsorbed oxygen on the SnO/sub 2/ surface is found to play a dominant role in the observed fast response characteristics.     

High-potential magnetic anisotropy of CoPtCr-SiO/sub 2/ perpendicular recording media

The magnetic anisotropy of CoPtCr-SiO/sub 2/ perpendicular recording media, including higher energy terms, was studied as a function of film composition and seed layer materials. All series of CoPtCr films with various Cr content, deposited on Ru seed layers, show maximum values of total anisotropy K/sub u/ at 25-30 at%Pt. The maximum value for CoPt(Cr=0) films reaches /spl sim/15/spl times/10/sup 6/ erg/cm/sup 3/. The addition of SiO/sub 2/ to the CoPtCr films reduces the grain K/sub u/, however the grain K/sub u/ maintains a large value of 8/spl times/10/sup 6/ erg/cm/sup 3/ even when 10at%SiO/sub 2/ is added to (Co/sub 90/Cr/sub 10/)/sub 80/Pt/sub 20/, for instance, which indicates the high-potential thermal stability. Theoretical calculations for media designs of 400 Gbits/in/sup 2/ revealed that the ratio of the high-energy anisotropy term K/sub u2/ to K/sub u1/(K/sub u/=K/sub u1/+K/sub u2/) is required to be 0.2-0.35 to enhance the energy barrier for the remanent state, without a notable change in switching field. The films deposited on Ru seed layers were found to show negligibly small K/sub u2/ values, however, the values of K/sub u1/ and K/sub u2/ vary significantly with the seed layer material used. K/sub u1/ decreases almost linearly as the K/sub u2/ value increases. It is concluded that CoPtCr films have a sufficient potential in the values of K/sub u1/ and K/sub u2/ for high-density perpendicular media.     

Influence of spinel substrate and over-layer for enhanced SAW and AO properties with KNbO3 thin film

Surface acoustic wave (SAW) propagation characteristics have been studied using modeling calculations for a potassium niobate (KNbO/sub 3/) thin film-layered structure with [001] and [110] orientation on a single crystal spinel (MgAl/sub 2/O/sub 4/) substrate, and a spinel buffer layer on silicon. Variation in the electromechanical coupling and acoustic attenuation has been compared. A significantly high value of coupling factor (k/sub max//sup 2/=23%) is obtained for the [001]KNbO/sub 3//spinel structure by introducing an optimum thickness of spinel over-layer for potential wide bandwidth SAW device applications. The dispersion characteristics with the [110] KNbO/sub 3/ orientation indicate an initial peak in the coupling coefficient value (k/sub max//sup 2/=8.8%) at a relatively low KNbO/sub 3/ film thickness that appears attractive for fabricating devices with thinner films. The KNbO/sub 3/ film with [001] orientation is found attractive for efficient acousto-optic (AO) device application with the formation of a symmetric waveguide structure (spinel(0.5 /spl mu/m)/KNbO/sub 3/(1.0 /spl mu/m)/spinel). A high value of k/sup 2/=23.5% with 50% diffraction efficiency has been obtained for the spinel(0.5 /spl mu/m)/KNbO/sub 3/(1.0 /spl mu/m)/spinel structure at 1 GHz SAW frequency and 633 nm optical wavelength at a very low input drive power of 15.4 mW.     

The /spl plusmn/45/spl deg/ correlation interferometer as a means to measure phase noise of parametric origin

A radiofrequency interferometric detector is combined with the correlation-and-averaging technique in a new scheme for the measurement of the phase noise of a component. The method relies upon the assumption that the phase noise of the component being tested (DUT) exceeds the amplitude noise, which is consistent with the general experience in the field of wireless engineering. The new scheme is based on the amplification of the DUT noise sidebands and on the simultaneous measurement of the amplified noise by means of two mixers driven in quadrature, /spl plusmn/ 45/spl deg/ off the carrier phase. The /spl plusmn/45/spl deg/ detection has two relevant properties, namely 1) the sensitivity is neither limited by the thermal energy k/sub B/T/sub 0/, nor by temperature uniformity, and 2) the noise of the measurement amplifier is rejected, despite a single amplifier being shared by the two channels of the correlator. The article provides the theoretical background and experimental results. The sensitivity of the first 100-MHz prototype, given in terms of the S/sub /spl phi//(f) floor, is some 12 dB below k/sub B/T/P/sub 0/, where P/sub 0/ is the carrier power. Using a dual carrier suppression scheme, the residual flicker is as low as -168 dBrad/sup 2//Hz at f=1 Hz off the carrier.     

Gas-sensing properties of sprayed films of (CdO)/sub x/(ZnO)/sub 1-x/ mixed oxide

A novel NO/sub 2/ sensor based on (CdO)/sub x/(ZnO)/sub 1-x/ mixed-oxide thin films deposited by the spray pyrolysis technique is developed. The sensor response to 3-ppm NO/sub 2/ is studied in the range 50/spl deg/C-350/spl deg/C for three different film compositions. The device is also tested for other harmful gases, such as CO (300 ppm) and CH/sub 4/ (3000 ppm). The sensor response to these reducing gases is different at different temperatures varying from the response typical for the p-type semiconductor to that typical for the n-type semiconductor. Satisfactory response to NO/sub 2/ and dynamic behavior at 230/spl deg/C, as well as low resistivity, are observed for the mixed-oxide film with 30% Cd. The response to interfering gas is poor at working temperature (230/spl deg/C). On the basis of this study, a possible sensing mechanism is proposed.     

Study of x/spl alpha/-Fe/sub 2/O/sub 3/-(1-x)ZrO/sub 2/ solid solution for low-temperature resistive oxygen gas sensors

A noble type of oxygen-sensitive and electrical-conductive material, ZrO/sub 2/-based with /spl alpha/-Fe/sub 2/O/sub 3/ thick-film gas sensor, was investigated for low operating temperature. Amorphous-like solid solutions of x/spl alpha/-Fe/sub 2/O/sub 3/-(1-x)ZrO/sub 2/ powders were derived using the high-energy ball milling technique, and their physical and microstructural properties were characterized from DTA, XRD, TEM, and XPS. The oxygen gas-sensing properties of the screen-printed thick-film gas sensors fabricated from such mechanically-alloyed materials were characterized systematically. Very good sensing properties were obtained with a relative resistance value of 82 in 20% oxygen, and at a low operating temperature of 320/spl deg/C. AC impedance spectra and thermally stimulated current were characterized to investigate the conduction properties of the solid solution, 0.2/spl alpha/-Fe/sub 2/O/sub 3/-0.8ZrO/sub 2/, in air and nitrogen (carrier gas), respectively. It was found that the Arrhenius plots of /spl sigma/T versus 1000/T have two distinct gradients corresponding to two activation energies in the high and low temperature regions. The transition temperature occurs at about 320/spl deg/C that corresponds to an optimal operating temperature of the gas sensor. It is believed that the high oxygen vacancy concentration present in the solid solution, 0.2/spl alpha/-Fe/sub 2/O/sub 3/-0.8ZrO/sub 2/, and the dissociation of the associated oxygen vacancy defect complexes at 320/spl deg/C are the critical factors for the high relative resistance to oxygen gas at low operating temperature.     

50-nm fully depleted SOI CMOS technology with HfO/sub 2/ gate dielectric and TiN gate

In this paper, we demonstrate for the first time CMOS thin-film metal gate FDSOI devices using HfO/sub 2/ gate dielectric at the 50-nm physical gate length. Symmetric V/sub T/ is achieved for long-channel nMOS and pMOS devices using midgap TiN single metal gate with undoped channel and high-k dielectric. The devices show excellent performance with a I/sub on/=500 /spl mu/A//spl mu/m and I/sub off/=10 nA//spl mu/m at V/sub DD/=1.2 V for nMOSFET and I/sub on/=212 /spl mu/A//spl mu/m and I/sub off/=44 pA//spl mu/m at V/sub DD/=-1.2 V for pMOSFET, with a CET=30 /spl Aring/ and a gate length of 50 nm. DIBL and SS values as low as 70 mV/V nand 77 mV/dec, respectively, are obtained with a silicon film thickness of 14 nm. Ring oscillators with 15 ps stage delay at V/sub DD/=1.2 V are also realized.     

Generation-recombination noise in pseudomorphic Modulation-doped Al/sub 0.2/Ga/sub 0.8/As/In/sub 0.1/Ga/sub 0.9/As/GaAs micro-Hall devices

The noise spectrum in micro-Hall devices based on pseudomorphic Al/sub 0.2/Ga/sub 0.8/As/In/sub 0.1/Ga/sub 0.9/As/GaAs modulation-doped heterostructures was measured between 4 Hz and 65 kHz, allowing components due to thermal, 1/f, and generation-recombination to be characterized. Applying deep level noise spectroscopy (DLNS) in the temperature range of 77-300 K to analyze the generation-recombination part of the spectrum, two electron traps contributing to noise density were identified. An emission activation energy of 474 meV was measured for the dominant trap, corresponding to the well-known DX center originating from the AlGaAs barrier. The other deep level, with an emission activation energy of 242 meV, is probably related to defects in the InGaAs layer. The structures under investigation resulted in high-performance micro-Hall devices: a supply-current-related sensitivity up to 725 V/spl middot/A/sup -1//spl middot/T/sup -1/ at 77 K independent of bias current, a signal-to-noise sensitivity of 155 dB/spl middot/T/sup -1/ and a detection limit of 340 pT/spl middot/mm/spl middot/Hz/sup -1/2/ at 77 K were measured.     

Compression of cross-linked poly(vinylidene fluoride-co-trifluoro ethylene) films for facile ferroelectric polarization

In this study, we demonstrated a facile route for enhancing the ferroelectric polarization of a chemically cross-linked poly(vinylidene fluoride-co-trifluoro ethylene) (PVDF-TrFE) film. Our method is based on thermally induced cross-linking of a PVDF-TrFE film with a 2,2,4-trimethyl-1,6-hexanediamine (THDA) agent under compression. The remanent polarization (P(r)) of a metal/ferroelectric/metal capacitor containing a cross-linked PVDF-TrFE film increased with pressure up to a certain value, whereas no change in the P(r) value was observed in the absence of THDA. A film cross-linked with 10 wt % THDA with respect to PVDF-TrFE under a pressure of 100 kPa exhibited a P(r) of approximately 5.61 μC/cm(2), which is 1.6 times higher than that in the absence of pressure. The enhanced ferroelectric polarization was attributed to highly ordered 20-nm-thick edge-on crystalline lamellae whose c-axes are aligned parallel to the substrate. The lamellae were effective for ferroelectric switching of the PVDF-TrFE when a cross-linked film was recrystallized under pressure. Furthermore, compression of a PVDF-TrFE film with a topographically prepatterned poly(dimethyl siloxane) mold gave rise to a chemically cross-linked micropattern in which edge-on crystalline lamellae were globally oriented over a very large area.     

CO-sensing properties of In/sub 2/O/sub 3/-doped SnO/sub 2/ thick-film sensors: effect of doping concentration and grain size

In/sub 2/O/sub 3/-doped SnO/sub 2/ nanoparticles were prepared using sol-gel technique from 0.1-M solutions of both stannic chloride (SnCl/sub 4/ 5H/sub 2/O) and indium nitrate. The doping concentration was varied from 7.718/spl times/10/sup -5/ to 3.859/spl times/10/sup -4/ moles. The average particle size, as measured from XRD, SEM, and TEM analyses, varies from 34-130 nm as a result of powder calcination at different temperatures ranging from 300/spl deg/C-900/spl deg/C. Thick-film samples with a thickness of /spl sim/15 /spl mu/m, were tested for low concentration (15-1000 ppm) of CO in air ambient. The optimal temperature for CO sensing is found to be 220/spl deg/C-240/spl deg/C. A blue shift in the sensing temperature and increase in sensitivity factor (S/sub f/) is observed with increasing doping concentration of indium oxide. Maximum sensitivity factor of /spl sim/5 is found for the highest doping concentration (3.859/spl times/10/sup -4/ moles) at 1000 ppm of CO concentration. The morphological and elemental studies of the film are carried out using SEM, TEM, XRD, and EDAX techniques. The results are discussed based on elemental analyses and available theories.     

The comparative effect of two different annealing temperatures and times on the sensitivity and long-term stability of WO/sub 3/ thin films for detecting NO/sub 2/

We have deposited 150-nm-thick WO/sub 3/ films on Si/sub 3/N/sub 4//Si substrates provided with platinum interdigital electrodes and annealed in static air at 300/spl deg/C and 500/spl deg/C temperatures for 24 h and 200 h. The morphology, crystalline phase, and chemical composition of the films have been characterized using AFM, grazing incidence XRD and high resolution XPS techniques. The sensor resistance response curve has been obtained in the 0.2 -4 ppm NO/sub 2/ gas concentration range in humid air (50% relative humidity), varying the operating temperature between 25 and 250/spl deg/C. By plotting both sensor resistance and gas concentration logarithmically, the response is linear over the investigated dynamic range. Sensor sensitivities, here defined as the ratio of sensor resistance in gas to that in air (i.e., S=R/sub Gas//R/sub Air/), have been compared at a given NO/sub 2/ gas concentration (0.2 ppm). The long-term stability properties have been evaluated by recording film sensitivity for 1 yr under standardized test conditions. Increasing the annealing temperature from 300 to 500/spl deg/C causes the sensitivities to decrease. The 300/24h film is shown to be the most sensitive at S=233, but with poor long-term stability properties. The 300/200h film with S=32 is stable over the examined period. The 500/24 and the 500/200 films are shown to be less sensitive with S=16 and S=14, respectively. The longer the annealing time and the higher the temperature, the poorer the sensitivity, but with positive effects upon the long-term stability of the electrical response. The influence of the annealing conditions on sensitivity and long-term stability has been correlated with the concentration of surface defects, like reduced WO/sub 3/ phase (i.e., W/sup 4+/), which resulted in a strong effect on the sensors' response.     

Spin-transfer switching current distribution and reduction in magnetic tunneling junction-based structures

Spin transfer switching current distribution within a cell and switching current reduction were studied at room temperature for magnetic tunnel junction-based structures with resistance area product (RA) ranged from 10 to 30 /spl Omega/-/spl mu/m/sup 2/ and TMR of 15%-30%. These were patterned into current perpendicular to plane configured nanopillars having elliptical cross sections of area /spl sim/0.02 /spl mu/m/sup 2/. The width of the critical current distribution (sigma/average of distribution), measured using 30 ms current pulse, was found to be 3% for cells with thermal factor (KuV/k/sub B/T) of 65. An analytical expression for probability density function p(I/I/sub c0/) was derived considering a thermally activated spin transfer model, which supports the experimental observation that the thermal factor is the most significant parameter in determining the within-cell critical current distribution. Spin-transfer switching current reduction was investigated through enhancing effective spin polarization factor /spl eta//sub eff/ in magnetic tunnel junction-based dual spin filter (DSF) structures. The intrinsic switching current density (J/sub c0/) was estimated by extrapolating experimental data of critical current density (J/sub c/) versus pulse width (/spl tau/), to a pulse width of 1 ns. A reduction in intrinsic switching current density for a dual spin filter (DSF: Ta/PtMn/CoFe/Ru/CoFeB/Al2O3/CoFeB/spacer/CoFe/PtMn/Ta) was observed compared to single magnetic tunnel junctions (MTJ: Ta/PtMn/CoFe/Ru/CoFeB/Al2O3/CoFeB/Ta). J/sub c/ at /spl tau/ of 1 ns (/spl sim/J/sub c0/) for the MTJ and DSF samples were 7/spl times/10/sup 6/ and 2.2/spl times/10/sup 6/ A/cm/sup 2/, respectively, for identical free layers. Thus, a significant enhancement of the spin transfer switching efficiency is seen for DSF structure compared to the single MTJ case.     

Dependence of ferroelectric and magnetic properties on measuring temperatures for polycrystalline BiFeO(3) films

A multiferroic BiFeO(3) film was fabricated on a Pt/Ti/SiO(3)/Si(100) substrate by a chemical solution deposition (CSD) method, and this was followed by postdeposition annealing at 923 K for 10 min in air. X-ray diffraction analysis indicated the formation of the polycrystalline single phase of the BiFeO(3) film. A high remanent polarization of 89 microC/cm(2) was observed at 90 K together with a relatively low electric coercive field of 0.32 MV/cm, although the ferroelectric hysteresis loops could not be observed at room temperature due to a high leakage current density. The temperature dependence of the ferroelectric hysteresis loops indicated that these hysteresis loops lose their shape above 165 K, and the nominal remanent polarization drastically increased due to the leakage current. Magnetic measurements indicated that the saturation magnetization was less than 1 emu/cm(3) at room temperature and increased to approximately 2 emu/cm(3) at 100 K, although the spontaneous magnetization could not appear. The magnetization curves of polycrystalline BiFeO3 film were nonlinear at both temperatures, which is different with BiFeO3 single crystal.     

The enhancement of Q factor for patterned ground shield inductors at high temperatures

We report on an effective way of using a patterned ground shield (PGS) to enhance the Q factor of on-chip spiral inductors. We fabricated PGS inductors using both 0.18 /spl mu/m and 0.35 /spl mu/m CMOS processes, with M1 and poly strip PGSs, respectively. The strip width and spacing of the PGSs are W/sub g/=0.8 /spl mu/m and S/sub g/=0.45 /spl mu/m, with metal thicknesses of t/sub p/={0.54,0.2} /spl mu/m in the 0.18 /spl mu/m process, and t/sub p/={0.6,0.3} /spl mu/m in the 0.35 /spl mu/m process. The separation distance D between PGS and top metal layer is different in both processes. We found that the Q factor degradation of inductors at high temperatures can be effectively compensated by using PGS. Among all geometric parameters of a PGS in the 0.18 /spl mu/m process, the parameter D is the critical factor for the shielding effectiveness, and M1 PGS is much more efficient than poly strip PGS in improving the inductor performance over the temperature range of 298 K to 358 K. However, in the 0.35 /spl mu/m process the latter is better than the former.