Effect of SGC on transient evolution of GWI in a Doppler broadened quasi Λ-type four-level system

In this paper,we study the effect of spontaneously generated coherence(SGC) on transient evolution of gain without inversion(GWI) in a Doppler broadened quasi Λ-type four-level atomic system.It is shown that transient evolution of GWI is very sensitive to the variation of SGC strength,and the transient maximum value and steady value of GWI both increase with SGC strength increasing.The transient and steady values of GWI with SGC are much larger than those without SGC.When Doppler broadening is present,the transient maximum value and steady value of GWI first increase and then decrease with Doppler broadening width(D) increasing,and the value of D which corresponds to the maximum transient GWI is different from that corresponding to the maximum steady GWI.The time needed for reaching the steady GWI increases with D increasing.The steady GWI,which is larger than that without Doppler broadening(D = 0),can be obtained by choosing appropriate D and SGC strength.     

Communicator mood and the reluctance to transmit undesirable messages (the Mum effect)

In order to examine the effects of mood on the transmission of good and bad news 48 female Ss, recruited for an “aesthetics experiment,” overheard a message intended for another S containing either good or had news, and were subsequently put into a pleasant or unpleasant mood. The results indicated that when Ss were confronted with the person for whom the message was intended (1) their mood tended to shift in a direction that was consistent with the affective nature of the message (p<.01); (2) good news was communicated more fully/spontaneously than bad news (p <.01); and (3) Ss in an initially unpleasant mood tended to communicate more spontaneously than Ss in a pleasant mood (p <.05), especially when the news was good.     

Influence of relative phase on propagation effect in open V-type three-level system

In this paper we study the influence of the relative phase between the probe and driving fields on propagation effect in an open Doppler broadening V-type three-level atomic system with spontaneously generated coherence(SGC) by using the calculation result of the density matrix motion equations and the propagation equations of the driving and probe fields.It is shown that the relative phase(Φ) has remarkable periodical influence on the propagation effect,and the period is 2π.By selecting appropriate value of Φ,we can get larger lasing without in version(LWI) gain and longer propagation distance in which gain exists,and hence obtain higher probe field(i.e.LWI) intensity.When Φ=π/2,the largest LWI gain and probe field intensity can be got.In addition,the atomic exit rate(γ0) and ratio(S) of the atomic injection rates also have a considerable modulation role on the phase-dependent propagation effect.In certain value range of γ0(S),LWI gain and probe field intensity increase with γ0(S) increasing.In the open system,LWI gain and probe field intensity much larger than those in the corresponding closed system can be obtained.     

The Effects of Implant Activation Anneal on the Effective Inversion Layer Mobility of 4H-SiC MOSFETs

In this paper, we investigate the effective inversion layer mobility of lateral 4H-SiC metal oxide semiconductor field-effect transistors (MOSFETs). Initially, lateral n-channel MOSFETs were fabricated with three process splits to investigate phosphorus implant activation anneal temperatures of 1200, 1650, and 1800°C. Mobility results were similar for all three temperatures (using a graphite cap at 1650°C and 1800°C). A subsequent experiment was performed to determine the effect of p-type epi-regrowth on the highly doped p-well surface. The negative effects of the high p-well doping are still seen with 1500 ? p-type regrowth, while growing 0.5 μm or more appears to be sufficient to grow out of the damaged area. A continuing series of tests are being conducted at present.     

Nonstationary thermoelectric power in multilayered structures with p-n junctions

It is shown that the nonstationary thermoelectric power with characteristic rise and fall times of the order of seconds in multilayered structures with p-n junctions can be several orders of magnitude greater than the stationary thermoelectric power in a homogeneous semiconductor. This effect can be observed in polycrystalline films and artificially produced multilayer structures with p-n junctions and thin layers. It can be used to produce ultrasensitive temperature sensors. Fiz. Tekh. Poluprovodn. 31, 920–921 (August 1997)     

Absorption-amplification response with or without spontaneously generated coherence effect in a four-level atomic system

We discuss and analyze the absorption properties of a weak probe field in a typical four-level atomic system in the presence of a spontaneously generated coherence (SGC) term. The influences of the SGC and a coherent pump field on the probe absorption-amplification are investigated. The results show that the absorption of such a weak probe field can be dramatically enhanced due to the SGC effect. At the same time, the probe-absorption profile exhibits a two-peak structure and the probe-absorption peak gradually decreases as the pump intensity increases. On the contrary, the amplification of such a weak probe field near the line center of the probe transition can be achieved by adjusting the coherent pump field intensity in the absence of the SGC effect.     

Coupling constant of triple-clad long-period fiber grating

Because of its high sensitivity to external refractiveindex,the long-period fiber grating(LPFG) has beenused as chemical sensor1-3.Now the multi-clad LPFGwiththe fil ms coated on cladding area of the fiber grat-ing has drawn much attention[4].It cani mpro…     

Performance evaluation of p-cycle based protection methods for provisioning of dynamic multicast sessions in mesh WDM networks

Network survivability is crucial to both unicast and multicast traffic. Up to now, extensive research has been done on unicast traffic protection. Recently, due to the rapid growth of multicast applications, such as video-conferencing, high definition television (HDTV), distance learning, and multi-player on-line gaming, the problem of multicast traffic protection has started to draw more research interests. The preconfigured protection cycle (p-cycle) method proposed by Grover offers fast speed in restoration (because p-cycles are pre-cross-connected) and high efficiency in resource utilization (because p-cycles protect both on-cycle and straddling links). So far p-cycles based protection approaches have been intensively studied for unicast traffic protection, but have been rarely investigated for multicast traffic. We propose to apply p-cycles to dynamic protection provisioning of multicast traffic, and evaluate the blocking performance in comparison to other existing multicast protection schemes. We consider three different p-cycle based multicasting protection methods, namely dynamic p-cycle (DpC) design, p-cycle based protected working capacity envelope (PWCE) design, and hybrid DpC and PWCE design. We show that p-cycle-based multicast protection approaches offer much better blocking performance, as compared with other existing multicast protection schemes. The main reasons for the much better blocking performance are attributed to the facts that (i) the selection of p-cycles is independent of the routing of the multicast light trees, (ii) there are no path/segment disjoint constraints between the selected p-cycles and the multicast light trees to be protected, (iii) the selected p-cycles are the most efficient p-cycles.

Properties of interfaces in GaInP solar cells

The effect of the properties of interfaces with Group-III phosphides on characteristics of GaInP solar cells has been studied. It is shown that the large valence band offset at the p-GaAs/p-AlInP interface imposes fundamental limitations on the use of p-AlInP layers as a wide-band-gap window in p-n structures of solar cells operating at ratios of high solar light concentration. It is demonstrated that characteristics of p-n solar cells can be, in principle, improved by using a double-layer wide-band-gap window constituted by p-Al_0.8Ga_0.2As and p-(Al_0.6Ga_0.4)_0.51In_0.49P layers.     

THEORETICAL ANALYSIS OF THE PRESSUREMAGNETO-ELECTRIC EFFECT OF JFET

In this paper the pressure-magneto-electric effect of Junction Field Effect Transistor(JFET)is discussed by using standard relaxation techniques.A theoretical evaluation of thepressure sensitivity and Hall sensitivity of the n-channel silicon JFET with various geometries(W/L),gate voltages(V_(FS))and drain voltages(V_(DS))is made.The results show that whenP≠0,B=0,the current-pressure sensitivity is about 2.5%.cm~2/N,supposing W/L(?)1/2-1.Based on that,a junction field effect pressure sensor with high stability and low noise is designed.     

p-Cycle Design in Survivable WDM Networks with Shared Risk Link Groups (SRLGs)

p-Cycle survivable network design under the single link failure assumption has been studied extensively. Shared risk link group (SRLG) is a concept that better reflects the nature of network failures. An SRLG is a set of links that may fail simultaneously because of a common risk they share. The capability of dealing with SRLG failures is essential to network survivability. In this paper, we extend the p-cycle survivable network design from the single link failure model to the single SRLG failure model. An integer linear programming (ILP) formulation that minimizes spare capacity requirement is provided. To avoid enumerating all cycles of a network, we also provide a polynomial-time algorithm to generate a basic candidate p-cycle set that guarantees 100% restorability in case of any single SRLG failure given enough spare capacities. Moreover, we present the SRLG failure detection problem that prevents fast restoration upon an SRLG failure. To solve this problem, we introduce the concept of SRLG-independent restorability, which enables the restoration of each link in a failed SRLG to start immediately without knowing which SRLG has failed. We present an approach to optimal p-cycle design with SRLG-independent restorability and show that it is NP-hard to generate a candidate p-cycle set such that each link can be SRLG-independently restored by at least one cycle in the set.     

Hall effect analysis of high purity p-type GaAs grown by metalorganic chemical vapor deposition

Variable temperature Hall effect and low temperature photoluminescence measurements have been performed on high purityp- andn-type GaAs grown at atmospheric pressure by metalorganic chemical vapor deposition. These high purity epitaxial GaAs layers were grown as a function of the arsine (AsH₃) to trimethylgallium (TMG) ratio (V/III ratio). The accurate quantitative assessment of the electronic properties of thep-type layers was emphasized. Analysis of the material focussed on the variation of the concentration of the shallow impurities for different V/III ratios. Surface and interface depletion effects are included to accurately estimate the concentration of impurities. The model of the merging of the excited states of the acceptor with the valence band is used to include the dependence the activation energy of the impurity on the acceptor concentration as well as on acceptor species identity. The characteristicp- ton-type conversion with increasing V/III ratio was observed in these samples and the reason for thep- ton-type conversion is that the background acceptor concentration of carbon decreases and the germanium donor concentration increases as the V/III ratio is increased.     

Electrical Characteristics of <Emphasis Type="Italic">n</Emphasis>-ZnO/<Emphasis Type="Italic">p</Emphasis>-Si Heterojunction Diodes Grown by Pulsed Laser Deposition at Different Oxygen Pressures

Heterojunction diodes of n-type ZnO/p-type silicon (100) were fabricated by pulsed laser deposition of ZnO films on p-Si substrates in oxygen ambient at different pressures. These heterojunctions were found to be rectifying with a maximum forward-to-reverse current ratio of about 1,000 in the applied voltage range of −5 V to +5 V. The turn-on voltage of the heterojunctions was found to depend on the ambient oxygen pressure during the growth of the ZnO film. The current density–voltage characteristics and the variation of the series resistance of the n-ZnO/p-Si heterojunctions were found to be in line with the Anderson model and Burstein-Moss (BM) shift.     

Epitaxial Growth and Characterization of p-Type ZnO

N-doped p-type ZnO thin films were grown on c-sapphire substrates, semi-insulating GaN templates, and n-type ZnO substrates by metal organic chemical vapor deposition (MOCVD). Diethylzinc and oxygen were used as precursors for Zn and O, respectively, while ammonia (NH₃) and nitrous oxide (N₂O) were employed as the nitrogen dopant sources. X-ray diffraction (XRD) studies depicted highly oriented N-doped ZnO thin films. Photoluminescence (PL) measurements showed a main emission line around 380 nm, corresponding to an energy gap of 3.26 eV. Nitrogen concentration in the grown films was analyzed by secondary ion mass spectrometry (SIMS) and was found to be on the order of 10¹⁸ cm⁻³. Electrical properties of N-doped ZnO epilayers grown on semi-insulating GaN:Mg templates were measured by the Hall effect and the results indicated p-type with carrier concentration on the order of 10¹⁷ cm⁻³.     

Plasma display panel with micro-discharge array

In 1996 , Schoenbach created the termof micro-hol-lowcathode discharge for the first ti me on the basis ofhollowcathode discharge[1].Fig.1 shows the electrodegeometries and electric circuit for a micro-hollowcath-ode discharge. The electrode geometry consists of acathode or anode, whichis composed of metal sheets of100μmthickness , separated by an insulator sheets ofseveral hundreds of micron. Two closely spaced elec-trodes with cylindrical openings of several hundreds ofmicronin diameter wit…     

Effect of High-Density Plasma Process Parameters on Carrier Transport Properties in <Emphasis Type="Italic">p</Emphasis>-to-<Emphasis Type="Italic">n</Emphasis> Type Converted Hg<Subscript>0.7</Subscript>Cd<Subscript>0.3</Subscript>Te Layer

Exposure of p-type HgCdTe material to Ar/H₂-based plasma is known to result in p-to-n conductivity-type conversion. While this phenomenon is generally undesirable when aiming to perform physical etching for device delineation and electrical isolation, it can be used in a novel process for formation of n-on-p junctions. The properties of this n-type converted material are dependent on the condition of the plasma to which it is exposed. This paper investigates the effect of varying the plasma process parameters in an inductively coupled plasma reactive ion etching (ICPRIE) tool on the carrier transport properties of the p-to-n type converted material. Quantitative mobility spectrum analysis of variable-field Hall and resistivity data has been used to extract the carrier transport properties. In the parameter space investigated, the n-type converted layer carrier transport properties and depth have been found to be most sensitive to the plasma process pressure and temperature. The levels of both RIE and ICP power have also been found to have a significant influence.     

Investigation on pulse properties of impregnated barium scandate dispenser cathodes

 In this paper, an impregnated barium acandate dispenser cathode primarily for application in microwave tubes, especially in gyrotrons, is investigated in the following aspecta: (1) pulse emission ability and work function distribution; (2) electron initial velocity distribution in pulse operation; (3) the effect of pulse duration ratio; (4) the anomalous Schottky effect under intensive electric field. Some useful results are obtained: the pulse current density is higher than 20 A/cm~2 (when T_k =850℃); the anomalous Schottky effect is observed when the field intenaity is higher than 10~4 V/cm; the cathode has flat J_-ft characteriatic when the pulse duration ratio is in the range of 5×10~(-3)--4×10~(-2) and an emission current density of 8.8 A/cm~2 is drawn. Finally, the experimental results are discussed in relation to papers of the cathode surface analysis published at home and abroad.     

Basis Translation Matrix between Two Isomorphic Extension Fields via Optimal Normal Basis

This paper proposes a method for generating a basis translation matrix between isomorphic extension fields. To generate a basis translation matrix, we need the equality correspondence of a basis between the isomorphic extension fields. Consider an extension field F_p^m where p is characteristic. As a brute force method, when p^m is small, we can check the equality correspondence by using the minimal polynomial of a basis element; however, when p^m is large, it becomes too difficult. The proposed methods are based on the fact that Type I and Type II optimal normal bases (ONBs) can be easily identified in each isomorphic extension field. The proposed methods efficiently use Type I and Type II ONBs and can generate a pair of basis translation matrices within 15 ms on Pentium 4 (3.6 GHz) when mlog₂ p = 160.     

Locally reconfigurable p-cycle networks for dual-failure restoration

p-Cycle reconfiguration methods (for instance complete, incremental, or dynamic-repair) based on the first event adaptive restoration model provide a promising approach for improving the dual-failure restorability characteristics of static p-cycle methods based on the static preplanned restoration model. However, if the reconfiguration process triggered by the first failure is not completed before a second failure occurs, p-cycle reconfiguration methods fail to achieve 100% dual-failure restorability and reduce to the static p-cycle methods which do not take advantage of the spare capacity to be reconfigured. In this study, we propose to use a new restoration model designated as first event locally adaptive restoration model with a coordinated re-restoration effort. This model is aimed to limit the reconfiguration scope to a local p-cycle where the spare capacity is only reconfigured on its straddling links for reducing the reconfiguration overhead (i.e., the average number of reconfigured links during the reconfiguration time.) According to this model, a two-phase locally reconfigurable p-cycle method is proposed. Only the straddling links of the local p-cycle affected by the first failure are reconfigured in the first phase. The second phase is not initialized until the second failure really occurs in the affected local p-cycle. The second phase is to enable the dual-failure restorations with a coordinated re-restoration effort for the first failed link from its original end nodes for any damage that the second failure causes to previously deployed restoration paths. The objective of the proposed method is to maximize the dual-failure restorability within a limited reconfiguration scope. We evaluate the correlation between the normalized spare capacity cost and the dual-failure restorability. The results show that the proposed local reconfiguration heuristic method improves the average dual-failure restorability of the 9n17s and Cost 230 networks by 45.1% and 20.1%, respectively, relative to the static p-cycles method and achieves closely the optimal value obtained using integer linear programming (ILP). Additionally, the spare capacity cost of the proposed local reconfiguration method is smaller than that of previous p-cycle reconfiguration methods in the two test networks.

Effects of field implants on small geometry CMOS devices

The various aspects of field implants have been studied with reference to a 3 μm CMOS p-well process developed at the author's organisation. It has been found that p-field (adjacent to p-channel tranistors) implant is not required for a low voltage (1.5 V) process. Both p- and n-field implants are, however, essential for a high voltage (5 V) process. The threshold voltage for a narrow width n-channel transistor is found to be increased from 0.3 V to 2.5 V as compared to that of a large width transistor if the field implant is followed by a long high temperature step. The increase in threshold in the case of a narrow p-channel transistor is observed to be from 0.35 V to 1.65 V under the same conditions. Such a large increase in the threshold voltage can, however, be prevented by a proper design of the process. It has also been observed that arsenic is an unsuitable species for p-field implants.