共查询到20条相似文献,搜索用时 31 毫秒
1.
Proton-exchanged Z -cut LiNbO3 planar waveguides formed using phosphoric acid were characterized optically. The refractive index profile and the diffusion parameters were studied systematically. These waveguides have propagation losses of less than 1 dB/cm and exhibit properties that are different from those obtained using benzoic acid. The index profile is not a simple step function and can be modeled accurately by a polynomial expression. A maximum surface index increase of 0.145 was measured at a 0.633-μm wavelength. The diffusion constant D 0 and the activation energy Q for the proton-exchange process using this acid were found to be 6.43×108 μm2/h and 82.91 kJ/mol, respectively. The annealing properties of these waveguides were also established, and the effects of annealing on surface index change and waveguide depth increase were found to follow a power-law relationship 相似文献
2.
The first demonstration of Bragg reflector grating filters in Ti:LiNbO3 single-mode channel guides is reported. Filter bandwidths as narrow as 0.14 nm centred at 1.476 μm have been achieved for TE polarisation in Y -cut (X -propagating) material 相似文献
3.
pin photodiodes with a 2.3 μm absorption edge are presented, using hydride vapour phase epitaxy. A Ga1-yInyAs (y =0.72) absorption layer, lattice-mismatched to the InP substrate, was grown on an InAsxP1-x (x =0-0.33) graded composition buffer layer. Typical dark current was 5 μA (0.03 A/cm2) at -6 V. Effective carrier lifetime of 0.05 μs was estimated from I/V characteristics 相似文献
4.
《Electron Devices, IEEE Transactions on》1990,37(1):153-158
The fabrication of a silicon heterojunction microwave bipolar transistor with an n+ a-Si:H emitter is discussed, and experimental results are given. The device provides a base sheet resistance of 2 kΩ/□ a base width 0.1 μm, a maximum current gain of 21 (V CE=6 V, I c=15 mA), and an emitter Gummel number G E of about 1.4×1014 Scm-4. From the measured S parameters, a cutoff frequency f t of 5.5 GHz and maximum oscillating frequency f max of 7.5 GHz at V CE=10 V, I c=10 mA are obtained 相似文献
5.
Reports a theory for calculating the coupling length L c of Ti:LiNbO3 single-mode waveguide directional couplers from process parameters and operating wavelength. Estimates are accurate to within a factor of 2 compared with published experimental results for z -cut y -propagating LiNbO3 devices for 0.63 μm⩽λ⩽1.56 μm. Use of this formalism to assess acceptable process parameter and wavelength tolerances is demonstrated 相似文献
6.
Patapoutian A. Kumar P.V. 《IEEE transactions on information theory / Professional Technical Group on Information Theory》1992,38(4):1375-1382
A simple technique employing linear block codes to construct (d ,k ) error-correcting block codes is considered. This scheme allows asymptotically reliable transmission at rate R over a BSC channel with capacity C BSC provided R ⩽C d,k-(1+C BSC), where C d,k is the maximum entropy of a (d ,k ) source. For the same error-correcting capability, the loss in code rate incurred by a multiple-error correcting (d ,k ) code resulting from this scheme is no greater than that incurred by the parent linear block code. The single-error correcting code is asymptotically optimal. A modification allows the correction of single bit-shaft errors as well. Decoding can be accomplished using off-the-shelf decoders. A systematic (but suboptimal) encoding scheme and detailed case studies are provided 相似文献
7.
Aina L. Burgess M. Mattingly M. O'Connor J.M. Meerschaert A. Tong M. Ketterson A. Adesida I. 《Electron Device Letters, IEEE》1991,12(9):483-485
The fabrication of 0.33-μm gate-length AlInAs/InP high electron mobility transistors (HEMTs) is reported. These InP-channel devices have f t values as high as 76 GHz, f max values of 146 GHz, and maximum stable gains of 16.8, 14, and 12 dB at 10, 18, and 30 GHz, respectively. The extrinsic DC transconductances are as high as 610 mS/mm; with drain-source breakdown voltages exceeding 10 V. The effective electron velocity in the InP channel is estimated to be at least 1.8×107 cm/s, while the f tL g product is 29 GHz-μm. These results are comparable to the best reported results for similar InGaAs-channel devices 相似文献
8.
A typical 1/f noise is excited in GaAs filament with the Hooge noise parameter of about αH=2×10-3 . The noise level increases in proportion to the square of the terminal voltage, and decreases approximately in inverse proportion to the total number of carriers within the device. A transition from the typical 1/f noise characteristics to the diffusion noise characteristics of MESFETs was observed when the electric field was increased above 1 kV/cm. The noise parameters were also investigated as a function of the device width between 2 and 200 μm. Deep levels within the n-GaAs active layer and the high electric field are the main factors of the nonideal 1/f characteristics 相似文献
9.
Peransin J.-M. Vignaud P. Rigaud D. Vandamme L.K.J. 《Electron Devices, IEEE Transactions on》1990,37(10):2250-2253
The 1/f noise in normally-on MODFETs biased at low drain voltages is investigated. The experimentally observed relative noise in the drain current S I/I 2 versus the effective gate voltage V G=V GS-V off shows three regions which are explained. The observed dependencies are S I/I 2∝V G m with the exponents m =-1, -3, 0 with increasing values of V G. The model explains m =-1 as the region where the resistance and the 1/f noise stem from the 2-D electron gas under the gate electrode; the region with m =0 at large V G or V GS≅0 is due to the dominant contribution of the series resistance. In the region at intermediate V G , m =-3, the 1/f noise stems from the channel under the gate electrode, and the drain-source resistance is already dominated by the series resistance 相似文献
10.
Yiqi Zhuang Qing Sun 《Electron Devices, IEEE Transactions on》1991,38(11):2540-2547
Accelerated life tests with high-temperature storage and electric aging for n+-p-n silicon planar transistors were carried out. Current gain h FE increases monotonously with time during the tests, and the h FE drift is correlated with initial measured 1/f noise in the transistors, i.e. the drift amount significantly increases with the increase of noise level. The correlation coefficient of relative drift Δh FE /h FE and 1/f noise spectral density S iB(f ) is far larger than that of Δ h FE/h FE and initial DC parameters of the transistors. A quantitative theory model for the h FE drift has been developed and explains the h FE drift behavior in the tests, which suggests that the h FE drift and 1/f noise can be attributed to the same physical origin, and both are caused by the modulation of the oxide traps near the Si-SiO2 interface to Si surface recombination. 1/f noise measurement, therefore, may be used as a fast and nondestructive means to predict the long-term instability in bipolar transistors 相似文献
11.
The asymptotic (M →∞) probability of symbol error P e,m for M -ary orthogonal modulation in a Nakagami-m fading channel is given by the incomplete gamma function P (m , mx ) where x =In 2/(E b/N 0) and E b is the average energy per bit. For large signal-to-noise ratio this leads to a channel where the probability of symbol error varies as the inverse m th power of E b/N 0. These channels exist for all m ⩾1/2. The special case of m =1 corresponds to Rayleigh fading, an inverse linear channel 相似文献
12.
AlGaAs/InGaAs P-n-p heterojunction bipolar transistors (HBTs) were fabricated using carbon-doped material grown by nonarsine metal-organic vapor-phase epitaxy (MOVPE). F max of 39 GHz and f t of 18 GHz were obtained. Operated in common-base mode, a P-n-p HBT achieved 0.5-W output power with 8-dB gain at 10 GHz; saturated output power was 0.69 W. Results are presented for devices with emitter lengths from 120 to 600 μm 相似文献
13.
Submicrometer-channel CMOS devices have been integrated with self-aligned double-polysilicon bipolar devices showing a cutoff frequency of 16 GHz. n-p-n bipolar transistors and p-channel MOSFETs were built in an n-type epitaxial layer on an n+ buried layer, and n-channel MOSFETs were built in a p-well on a p+ buried layer. Deep trenches with depths of 4 μm and widths of 1 μm isolated the n-p-n bipolar transistors and the n- and p-channel MOSFETs from each other. CMOS, BiCMOS, and bipolar ECL circuits were characterized and compared with each other in terms of circuit speed as a function of loading capacitance, power dissipation, and power supply voltage. The BiCMOS circuit showed a significant speed degradation and became slower than the CMOS circuit when the power supply voltage was reduced below 3.3 V. The bipolar ECL circuit maintained the highest speed, with a propagation delay time of 65 ps for C L=0 pF and 300 ps for C L=1.0 pF with a power dissipation of 8 mW per gate. The circuit speed improvements in the CMOS circuits as the effective channel lengths of the MOS devices were scaled from 0.8 to 0.4 μm were maintained at almost the same ratio 相似文献
14.
Optimal pump wavelength in the4I 15/2-4I 13/2 absorption band for efficient Er3+-doped fiberamplifiers
Zyskind J.L. Giles C.R. Desurvire E. Simpson J.R. 《Photonics Technology Letters, IEEE》1989,1(12):428-430
The authors report the measured gain of a highly efficient erbium-doped fiber amplifier pumped at wavelengths between 1.46 and 1.51 μm. The optimal pump wavelength, λopt, was determined to be 1.475 μm. At this wavelength, the maximum gain coefficients for signals at 1.531 and 1.544 μm were 2.3 and 2.6 dB/mW, respectively. At λopt, high gains ranging from 32 dB at pump power P p=20 mW up to 40 dB at P p=80 mW were obtained. These modest pump powers are within the capabilities of currently available 1.48-μm diode lasers. The width about λopt for 3-dB gain variation exceeded 27 nm for P p=10 mW and 40 nm for P p >20 mW. With this weak dependence on pump wavelength, single-longitudinal-mode lasers do not have a significant advantage over practical Fabry-Perot multimode pump lasers 相似文献
15.
It is shown that for worst-case partial-band jamming, the error probability performance (for fixed E b/N I) becomes worse with increasing M for (M >16). The asymptotic probability-of-error is not zero for any E b/N I(>ln 2), but decreases inverse linearly with respect to it. In the fading case, the error-probability performance (for fixed E b/N 0) improves with M for noncoherent detection, but worsens with M for coherent detection. For large E b/N 0 the performance of the Rayleigh fading channel asymptotically approaches the same limit as the worst case partial-band jammed channel. However, for values of M at least up to 4096, the partial-band jammed channel does better. While it is unlikely that an M -ary orthogonal signal set with M >1024 will be used in a practical situation, these results suggest an important theoretical problem; namely, what signal set achieves reliable communication 相似文献
16.
Ng G.I. Pavlidis D. Tutt M. Weiss R.M. Marsh P. 《Electron Devices, IEEE Transactions on》1992,39(3):523-532
Extensive bias-dependent and temperature-dependent low-frequency (LF) noise measurements were performed on lattice-matched and strained In0.52Al0.48As/InxGa1-x As(0.53<x <0.70) HEMTs. The input-noise voltage spectra density is insensitive to V DS bias and shows a minimum at V GS corresponding to the peak g m condition. The corresponding output-noise voltage spectral density, which depends strongly on the gain of the devices, increases with V DS. The input noise was rather insensitive to indium (In) content. Temperature-dependent low-frequency noise measurements on these devices reveal shallow traps with energies of 0.11, 0.15, and 0.18 eV for 60%, 65%, and 70% In HEMTs. Noise transition frequencies for these devices were on the order of 200-300 MHz and remain almost the same for different channel In content and V DS bias 相似文献
17.
Yan R.-H. Lee K.F. Jeon D.Y. Kim Y.O. Park B.G. Pinto M.R. Rafferty C.S. Tennant D.M. Westerwick E.H. Chin G.M. Morris M.D. Early K. Mulgrew P. Mansfield W.M. Watts R.K. Voshchenkov A.M. Bokor J. Swartz R.G. Ourmazd A. 《Electron Device Letters, IEEE》1992,13(5):256-258
The authors report the implementation of deep-submicrometer Si MOSFETs that at room temperature have a unity-current-gain cutoff frequency (f T) of 89 GHz, for a drain-to-source bias of 1.5 V, a gate-to-source bias of 1 V, a gate oxide thickness of 40 Å, and a channel length of 0.15 μm. The fabrication procedure is mostly conventional, except for the e-beam defined gates. The speed performance is achieved through an intrinsic transit time of only 1.8 ps across the active device region 相似文献
18.
Poly-Si resistors with an unimplanted channel region (and with n-type source/drain regions) can exhibit a nonhyperbolic sine (non-sinh) I -V characteristic at low V DS and an activation energy which is not simply decreasing monotonically with increasing V DS. These phenomena are not explained by conventional poly-Si resistor models. To describe these characteristics, a self-consistent model which includes the effects of a reverse-biased diode at the drain end is presented. Numerical simulation results show excellent agreement with experiment in regard to the shape of the I -V characteristic and of the effective activation energy as a function of V DS 相似文献
19.
Morkel P.R. Jedrzejewski K.P. Taylor E.R. Payne D.N. 《Photonics Technology Letters, IEEE》1992,4(6):545-547
A high-power, laser-diode-pumped, Q -switched fiber laser operating at 1.053 μm which is suitable for use in time-multiplexed fiber sensor applications is described. The laser emits >1-kW pulses at 1.053 μm with 2-ns duration at up to 1-kHz repetition rates for an adsorbed pump power of only 22 mW at 810 nm. Tunable Q -switched operation over a 40-nm wavelength range has also been demonstrated 相似文献
20.
An In0.41Al0.59As/n+-In0.65 Ga0.35As HFET on InP was designed and fabricated, using the following methodology to enhance device breakdown: a quantum-well channel to introduce electron quantization and increase the effective channel bandgap, a strained In0.41Al0.59As insulator, and the elimination of parasitic mesa-sidewall gate leakage. The In0.65Ga0.35As channel is optimally doped to N D=6×1018 cm-3. The resulting device (L g=1.9 μm, W g =200 μm) has f t=14.9 GHz, f max in the range of 85 to 101 GHz, MSG=17.6 dB at 12 GHz V B=12.8 V, and I D(max)=302 mA/mm. This structure offers the promise of high-voltage applications at high frequencies on InP 相似文献