共查询到20条相似文献,搜索用时 31 毫秒
1.
《Electron Devices, IEEE Transactions on》1973,20(4):371-379
An analytical investigation supported by numerical calculations has been performed of the stable field profile in a supercritical diffusion-stabilized n-GaAs transferred electron amplifier (TEA) with ohmic contacts. In the numerical analysis, the field profile is determined by solving the steady-state continuity and Poisson equations. The diffusion-induced short-circuit stability is checked by performing time-domain computer simulations under constant voltage conditions. The analytical analysis based on simplifying assumptions gives the following results in good agreement with the numerical results. 1) A minimum doping level required for stability exists, which is inversely proportional to the field-independent diffusion coefficient assumed in the simple analysis. 2) The dc current is bias independent and below the threshold value, and the current drop ratio increases slowly and almost linearly with the doping level. 3) The domain width normalized to the diode lengthL varies almost linearly with(V_{B}/V_{T}-1)^{frac{1}{2}}/(n_{0}L)^{frac{1}{2}} where VB is the bias voltage VT is the threshold voltage, and no is the doping level. 4) The peak domain field varies almost linearly with (V_{B}/V_{T}-1 )^{frac{1}{2}} (n_{0}L)^{frac{1}{2}} . Those results contribute to the understanding of the highn_{0}L -product switch and the stability of the supercritical TEA. 相似文献
2.
《Electron Devices, IEEE Transactions on》1974,21(1):89-93
Assuming the conventional divisions of the semiconductor into depleted and neutral regions, it is shown that for an abrupt p-n junction with nondegenerate carriers a relation exists between the open circuit photovoltage and the PN product at the junction(PN)_{0} , which is valid for all signal levels. In the small-signal case this leads to the standard result. At intermediate levels a new relationV = KT/q (1 pm m) log_{e} ([(PN)_{0}]^{1/2}/n_{i}) holds, the upper sign for p+-n junctions, the lower for n+-p junctions;m = (micro_{e}-micro_{h})/(micro_{e}+micro_{h}) . At very high levels the photovoltage saturates toV = kT/q[log_{e}(M_{p}M_{n}/n_{i^{2}}) + m log_{e}(micro_{h}M_{p}/micro_{e}M_{N})] . Since Mp and MN are the doping levels in the p and n regions, the first term is the diffusion potential and the second term will be positive for p+-n junctions and negative for n+-p junctions. These results compare satisfactorily with the available experimental data. 相似文献
3.
《Electron Devices, IEEE Transactions on》1982,29(6):965-970
It is found that equivalent gate noise power for l/f noise in n-channel silicon-gate MOS transistors at near zero drain voltage at room temperature is empirically described by two noise terms, which vary asK_{1}(q/C_{ox}) (V_{G} -V_{T})/f and K_{2}(q/C_{ox})^{2}/f, where V_{G} is gate voltage, VT is threshold Voltage, and Cox is gate-oxide capacitance per unit area. Unification of carrier-density fluctuation (McWhorter's model)and mobility fluctuation (Hooge's model) can account for the experimental data. The comparison between the theory and experiment shows that the carrier fluctuation term K2 is proportional to oxide-trap density at Fermi-level. The mobility fluctuation term K1 is correlated to K2 , being proportional toradic K_{2} . The origin of this correlation is yet to be clarified. 相似文献
4.
Multimode channel waveguides were formed by field-assisted diffusion of Ag+ ion from vacuum-evaporated Ag films, into a sodium aluminosilicate glass reported to yield high diffusion rates for alkali ions. Two-dimensional index profiles of channel waveguides formed by diffusion from a strip aperture were controlled by means of diffusion time, temperature, and electric field. The diffusion equation for diffusion through a strip aperture in the presence of a one-dimensional electric field was solved. Its solution was in agreement with measured concentration profiles:frac{C(x,y,t)}{C_{0}} = frac{1}{2} { erf (frac{a - x}{2sqrt{Dt}}) + erf (frac{a + x}{2sqrt{Dt}})} .frac{1}{2} { erfc (frac{y - muE_{y}t}{2sqrt{Dt}}) + e^{(yE_{y}/D)} erfc (frac{y + muE_{y}t}{2sqrt{Dt}})} Diffusion coefficients in this aluminosilicate glass were determined to beD =(2.41 times 10^{-13}) (frac{m^{2}}{s})) .exp (frac{-3.1 times 10^{4}frac{J}{mol}}{RT}) Diffusion coefficients were higher (between 150°C and 300°C) than those of a low-iron soda-lime silicate glass "standard" also studied, for which diffusion coefficients wereD =(3.28 times 10^{-13} (frac{m^{2}}{s})) .exp (frac{-3.6 times 10^{4}}{RT} (frac{J}{mol})) This difference in diffusion coefficients is due to the higher activation energy of diffusion in the soda-lime silicate glass. The Gladstone-Dale relation was used to calculate the maximum possible refractive index change via Ag+-Na+ ion-exchange for each type of glass. The maximum index change in the sodium aluminosilicate glass is found to be about 65 percent of that in the soda-lime silicate glass. 相似文献
5.
《Electron Device Letters, IEEE》2009,30(8):831-833
6.
《Electron Devices, IEEE Transactions on》1971,18(12):1186-1187
The noise temperature as a function of the applied field has been measured on an epitaxial silicon layer at the frequencies 2 GHz and 4 GHz. It has been found that the experimental results are in good agreement with the theory given by Moll. It is shown that for noise calculations in silicon field-effect transistors with pronounced carrier velocity saturation the noise temperature Tn versus field E may be approximated byT_{n}/T_{0} = 1 + γ(E/E_{c})^{2} with T0 = lattice temperature, Ec = saturation field, γ = const. 相似文献
7.
《Electron Devices, IEEE Transactions on》2009,56(4):678-682
8.
《Electron Devices, IEEE Transactions on》1970,17(5):420-423
The values 1-1/M for both electrons and holes, whereM is the multiplication factor, have been calculated in three different silicon p-n junctions. The logarithmic plot of 1 - 1/M versus the normalized voltageV/V_{B} is well approximated by a straight line for 0.1 > 1 -1/M > 0.005. This range corresponds to the useful range of α0 for most bipolar transistors. An empirical expression has been obtained for the ratioV_{CEO}/V_{CBO} within this range. 相似文献
9.
《Electron Devices, IEEE Transactions on》1977,24(10):1245-1248
A knowledge of the MOSFET operating in weak inversion is important for circuits with low leakage specifications. This paper discusses the effect of temperature on the MOSFET in weak inversion. The reciprocal slopen of the log IDS versus VGS relationship between source-drain current IDS and gate bias VGS may be given byfrac{1}{(n - 1 - gamma)^{2}} = frac{2Cmin{ox}max{2}}{qepsilon_{s}N_{B}} [frac{3}{4} frac{E_{g^{0}}{q} - (frac{3}{2}alpha + frac{k}{q})T] withalpha equiv (k/q)(38.2 - ln N_{B} + (3/2) ln T) and γ ≡C_{ss}/C_{ox} , where Cox is the oxide capacitance per unit area, Css the surface states capacitance per unit area,q the electronic charge, εs the permittivity of silicon, NB the bulk doping concentration,k the Boltzmann's constant,T the absolute temperature, andE_{g0} the extrapolated value of the energy gap of lightly doped silicon atT = 0 K. This theoretical formula was in good agreement with experimental results in a temperature range of interest. 相似文献
10.
Fast evaluation of logarithms in fields of characteristic two 总被引:4,自引:0,他引:4
《IEEE transactions on information theory / Professional Technical Group on Information Theory》1984,30(4):587-594
A method for determining logarithms in GF(2^{n}) is presented. Its asymptotic running time isO(exp (cn^{1/3} log^{2/3} n)) for a small constantc , while, by comparison, Adleman's scheme runs in timeO(exp (c^{'}n^{1/2} log^{1/2} n )) . The ideas give a dramatic improvement even for moderate-sized fields such as GF(2^{127}) , and make (barely) possible computations in fields of size around2^{400} . The method is not applicable to GF(q) for a large primeq . 相似文献
11.
《Quantum Electronics, IEEE Journal of》1981,17(8):1324-1325
Classically, the thermal noise in electricalRC circuits andLCR series circuits is governed by the equipartition lawfrac{1}{2}overline{CV^{2}} = frac{1}{2}kT , whereV(t) is the noise voltage developed acrossC . When quantum effects are taken into account, the equipartition law no longer holds forRC circuits, although an equipartition law can be deemed for the measured mean square noise voltage under certain conditions. InLCR series circuits the equipartition lawfrac{1}{2}overline{CV^{2}} = frac{1}{2}kT , changes intofrac{1}{2}overline{CV^{2}} = frac{1}{2}bar{E}(f_{0}) for high-Q tuned circuits, wherebar{E}(f_{0}) is the average energy of a harmonic oscillator tuned at the tuning frequency of the tuned circuit. 相似文献
12.
《IEEE transactions on information theory / Professional Technical Group on Information Theory》1987,33(6):759-772
The multiterminal hypothesis testingH: XY againstH̄: X̄Ȳ is considered whereX^{n} (X̄^{n}) andY^{n} (Ȳ^{n}) are separately encoded at ratesR_{1} andR_{2} , respectively. The problem is to determine the minimumbeta_{n} of the second kind of error probability, under the condition that the first kind of error probabilityalpha_{n} leq epsilon for a prescribed0 < epsilon < 1 . A good lower boundtheta_{L}(R_{1}, R_{2}) on the power exponenttheta (R_{1}, R_{2},epsilon)= lim inf_{n rightarrow infty}(-1/n log beta_{n}) is given and several interesting properties are revealed. The lower bound is tighter than that of Ahlswede and Csiszár. Furthermore, in the special case of testing against independence, this bound turns out to coincide with that given by them. The main arguments are devoted to the special case withR_{2} = infty corresponding to full side information forY^{n}(Ȳ^{n}) . In particular, the compact solution is established to the complete data compression cases, which are useful in statistics from the practical point of view. 相似文献
13.
New results in binary multiple descriptions 总被引:3,自引:0,他引:3
《IEEE transactions on information theory / Professional Technical Group on Information Theory》1987,33(4):502-521
14.
《IEEE transactions on information theory / Professional Technical Group on Information Theory》1987,33(3):443-448
For a joint distribution{rm dist}(X,Y) , the functionT(t)=min { H(Y|U): I(U wedge Y|X)=O, H(X|U)geq t} is an important characteristic. It equals the asymptotic minimum of(1/n)H(Y^{n}) for random pairs of sequences(X^{n}, Y^{n}) , wherefrac{1}{n} sum ^{n}_{i=1}{rm dist} X_{i} sim {rm dist} X, {rm dist} Y^{n}|X^{n} = ({rm dist} Y|X)^{n}, frac{1}{n}H(X^{n})geq t. We show that if, for(X^{n}, Y^{n}) as given, the rate pair[(1/n)H(X^{n}) ,(1/n)H(Y^{n})] approaches the nonlinear part of the curve(t,T(t)) , then the sequenceX^{n} is virtually memoryless. Using this, we determine some extremal sections of the rate region of entropy characterization problems and find a nontrivial invariant for weak asymptotic isomorphy of discrete memoryless correlated sources. 相似文献
15.
《Electron Device Letters, IEEE》1985,6(9):450-452
The n-channel LDD MOSFET lifetime is observed to followtau=(A/I_{d})(I_{sub}/I_{d})^{-n} from 77 to 295 K when the device is stressed near the maximum Isub . Here Id is the drain current andA is the proportionality constant. The experimental result indicates thatn is approximately 2.7 and is independent of temperature. However, the proportionality constantA followsA = A_{0} exp (-E_{a}/kT) , withE_{a} = 39 meV. The smaller proportionality constant at low temperatures suggests that hot-electron injection (HEI) degradation is caused by the electron trapping in the oxide. 相似文献
16.
Electromagnetic reflection from an extended turbulent medium: Cumulative forward-scatter single-backscatter approximation 总被引:2,自引:0,他引:2
The backscatter cross sectionQ for high-frequency irradiated turbulent dielectric media, many mean free pathsL_{1} wide, is computed. The lengthL_{1} is the distance into the medium over which the mean electric field decreases in amplitude by a factore^{-1} . Previous calculations have always been restricted toL ll L_{1} . It is found thatQ increases from the Born approximationQ = Q_{1} for medium widthL ll L_{1} toQ = 2Q_{1} forL gg L_{1} , and the theory is valid as long asL ll (kL_{0})^{5/3} L_{1} , a significant improvement over the Born approximation, when the macroscaleL_{0} is much larger than the wavelength2_{pi}k^{-1} . The improvement is due to incorporation of the dominant effects of cumulative forward scattering in the local electric field in the medium. A rigorous and a heuristic derivation are given. The transitional behavior is discussed and a simple physical interpretation is given. 相似文献
17.
《Electron Devices, IEEE Transactions on》1957,4(1):22-24
An approximate formula is developed for the current of a parallel-plane diode including the effects of initial velocities of emission. For an oxide-coated cathode (T = 1000 °K) the approximate result is:J = 2.33 times 10^{-6} frac{V^{3/2}}{x^{2}} cdot[1 + frac{11.4(J_{s}x^{2})^{1/4}}{V^{3/4}} + frac{3.22(J_{s}x^{2})^{1/8}}{V^{3/2}}] where,J , Js , andx are in suitable units such that Jx2andJ_{s}x^{2} are in amperes and V in volts. A comparison is made between this result, Child's 3/2 power solution, and the Epstein-Fry-Langmuir solution. The result given above being an explicit solution of the current is particularly advantageous over prior approximate solutions. 相似文献
18.
《Electron Device Letters, IEEE》2009,30(12):1278-1280
19.
《Electron Devices, IEEE Transactions on》1967,14(12):808-816
It is shown that the observed values of the minimum noise figureF_{min} of UHF transistors in common base connection can be explained in terms of the device parameter(1-alpha_{dc}) r_{b'b}/R_{e0} and fα for frequencies up to 1000 MHz. An interesting collector saturation effect is observed that gives a strong increase in UHF noise figure at high currents. Many features of the dependance ofF_{min} on operating conditions can be explained by this effect. The current dependence ofF_{min} for large values of |VCB | and high currents suggests a distribution in diffusion times through the base region. At intermediate frequencies, the noise figure increases with increasing collector bias |VCB | due to an increase inr_{b'b} , which in turn is caused by the dependence of the base width on |VCB |. 相似文献
20.
《Electron Devices, IEEE Transactions on》1972,19(5):681-690
Some MOS transistor models for computer-aided design, each having a given accuracy and complexity, are presented. These models apply before saturation and in the saturation region. Before saturation, the proposed theory takes into account the behavior of mobility versus gate-channel and drain-source biases. In the saturation region the effect of mobile carriers on the drain-channel space-charge layer in an approximate two-dimensional analysis is taken into account. This model has been checked for dc characteristicsI_{D} (V_{DS}) and different channel lengths, dynamic resistances in the saturation region, transfer characteristics of various inverters, and dynamic response of these circuits. The accuracy is within 5 percent. 相似文献