Time-domain response of MIS coplanar waveguides for MMICs

An MIS coplanar waveguide propagating a slow-wave mode has been characterised in the time domain. The theoretical analysis proposed to obtain the time-domain response of the line gives results in good agreement with measurements. The circuit analysis used is suitable for the determination of spurious propagation effects, inherent to the use of miniature waveguides encountered in MMICs, such as Schottky contact coplanar lines and coupled microstrip lines laid on MIS substrates.     

Propagation characteristics of MIS transmission lines withinhomogeneous doping profile

The authors present a hybrid-mode analysis of slow-wave MIS (metal-insulator-semiconductor) transmission lines with a gradually inhomogeneous doping profile. In general it was found that, in comparison with homogeneously doped semiconductor layers, a Gaussian-type doping distribution results in lower losses for the slow-wave mode in both thin- and thick-film MIS CPWs. While the effect of the doping profile is more pronounced in thin-film structures which support a slow-wave mode only up to 3 GHz, it is less significant in thick-film structures. On the other hand, numerical analysis indicates that thick-film structures can support a slow-wave mode at moderate loss up to 40 GHz. The behavior of MIS microstrip lines is similar to that of MIS CPWs, except that for thick-film transmission lines an increase in losses can be observed when the doping profile becomes inhomogeneous. The numerical investigation was carried out using the method of lines. Several transmission lines have been investigated, and results are presented for microstrip, coupled microstrips, and coplanar lines     

Rigorous analysis of planar MIS transmission lines

The realisation of distributed microwave integrated circuits can be expected by using very low phase velocity propagation modes on MIS and Schottky planar transmission lines. Up to now, the frequency behaviour of such lines has been obtained by using analytical models. We present a rigorous analysis of a MIS microstrip line, the validity of which is testified by comparison to experimental values.     

Application of Maxwell-Wagner polarization in delay lines

The propagation characteristics of metal-insulator-semiconductor (MIS) lines are controlled by the resistivity of the substrate, the operating frequency and the ratio of the semiconductor to insulator layer thicknesses. A strong interfacial polarisation, also known as the Maxwell-Wagner polarisation, is often responsible for the significant slow-down of the propagation velocity of MIS microstrip transmission lines. This phenomenon has been applied in the development of miniature delay lines exhibiting large electrical dimensions. In this paper we review most previously presented designs and we examine the effect of this polarization mechanism under various parameters. Finally, the presented micro-scale delay lines, exhibit comparable slowing factors with our predecessors at the cost of lower attenuation.     

Embedded microstrip interconnection lines for gigahertz digitalcircuits

Transmission line structures are needed for the high-performance interconnection lines of GHz integrated circuits (ICs) and multichip modules (MCMs), to minimize undesired electromagnetic wave phenomena and, therefore, to maximize the transmission bandwidth of the interconnection lines. In addition, correct and simple models of the interconnection lines are required for the efficient design and analysis of the circuits containing the interconnection lines. In this paper, we present electrical comparisons of three transmission line structures: conventional metal-insulator-semiconductor (MIS) and the embedded microstrip structures-embedded microstrip (EM) and inverted embedded microstrip (IEM). In addition, we propose closed-form expressions for the embedded microstrip structures EM and IEM and validate the expressions by comparing with empirical results based on S-parameter measurements and subsequent microwave network analysis. Test devices were fabricated using a 1-poly and 3-metal 0.6 μm Si process. The test devices contained the conventional MIS and the two embedded microstrip structures of different sizes. The embedded microstrip structures were shown to carry GHz digital signals with less loss and less dispersion than the conventional MIS line structures. S-parameter measurements of the test devices showed that the embedded microstrip structures could support the quasi-TEM mode propagation at frequencies above 2 GHz. On the other hand, the conventional MIS structure showed slow-wave mode propagation up to 20 GHz. More than 3-dB/mm difference of signal attenuation was observed between the embedded microstrip structures and the conventional MIS structure at 20 GHz. Finally, analytical RLCG transmission line models were developed and shown to agree well with the empirical models deduced from S-parameter measurements     

Hybrid-mode analysis of homogeneously and inhomogeneously dopedlow-loss slow-wave coplanar transmission lines

A hybrid-mode analysis is presented to characterize the propagation properties of uniplanar slow-wave MIS (metal-insulator-semiconductor) coplanar transmission lines. The effect of homogeneous versus gradually inhomogeneous doping profile is investigated as well as the influence of the metal conductor losses and finite metallization thickness on the slow-wave factor and the overall losses. Numerical results indicate that thick-film MIS CPWs can support a slow-wave mode with moderate loss up to 40 GHz when the line dimensions are kept in the micrometer range. Furthermore, it is found that an inhomogeneous doping profile can reduce the overall losses and that the effect of metal conductor losses in heavily doped MIS structures is only marginal. On the other hand, in weakly doped or insulating GaAs material a lossy metal conductor leads to a higher propagation constant, exhibiting a negative slope with increasing frequency     

New method for determining distribution of interface states in an MIS system

A general formula for the capacitance transient response in an MIS system was developed in order to apply the ICTS (isothermal capacitance transient spectroscopy) technique to an MIS diode. A new spectroscopic measurement method for determining the distribution of interface states is proposed and applied to an InAs MIS diode.     

Modal analysis of IncGaAsP-InP,GaAs/AlGaAs-GaAs,and InGaAsP/AlGaAs-GaAs MIS heterostructure lasers

The transverse modal behavior of Metal-Insulator (Oxide)-Semiconductor (MIS) heterostructure injection lasers is analyzed. MIS structures have been proposed by Jain and Marciniec as an alternate approach to p-n heterojunctions to obtain minority carrier injection and subsequent lasing action. In the modal analysis the MIS structure is treated as an asymmetrical three-layer slab waveguide with appropriate boundary conditions. Numerical computations of electric field strength, intensity and confinement factor P are presented for various GaAs and InP based MIS structures. A comparison of the output characteristics of a GaAs MIS laser with a conventional GaAs p-n double heterostructure laser is also reported.     

Determination of carrier mobility of semiconductor layer in organic metal-insulator-semiconductor diodes by displacement current and electric-field-induced optical second-harmonic generation measurements

A novel method for determining carrier mobility of semiconductor layer in thin-film organic metal-insulator-semiconductor (MIS) diodes is proposed, where displacement current measurement (DCM) is used in combination with electric-field-induced optical second-harmonic generation (EFISHG) measurement. EFISHG signals generated from the semiconductor layer probe the electric field caused by carriers moving in the semiconductor layer of MIS diodes. On the other hand, DCM signals generated in accordance with the time derivative of induced charge on metal electrode well identify the transit time of carriers across the semiconductor layer. By using Au/pentacene/polyimide (PI)/indium-tin-oxide (ITO) diodes, we experimentally determined the carrier mobility of the pentacene layer. Results and analysis showed that step-voltage application to MIS diodes is suitable for the use of this proposed method.     

Invited paper Characteristics of travelling waves along the non-linear transmission lines for monolithic integrated circuits: a review

A general analysis of non-linear wave propagation along transmission lines with voltage-dependent capacitance is presented. In particular, slow-wave structures like MIS and Schottky-barrier strip lines are examined. A spatial periodicity is included explicitly. The theoretical treatment is based on suitable equivalent circuits leading to characteristic wave equations. With regard to practical devices, the solutions show a variety of different phenomena as determined by the parameters of the non-linearity, dispersion and dissipation and the boundary conditions. Experimental results performed on a slow-wave model line are included.     

Effect of illumination on the characteristics of a proposedhetero-MIS diode

A novel heterostructure metal-insulator-semiconductor (MIS) diode is proposed and studied theoretically to examine the effect of illumination on the characteristics of the device. The capacitance of the proposed structure has been calculated in the dark as well as in various illuminated conditions. It is found that the capacitance of the proposed MIS diode can be controlled by varying the incident light intensity. By incorporating the capacitor in the tuned circuit of an oscillator it will be possible to convert the intensity-modulated optical signal. The device is also expected to find useful application in optical CCDs for solid-state imaging and optical tuning     

Lateral MIS tunnel transistor

A new device structure called the Lateral MIS Tunnel Transistor (LMISTT) is proposed, and its basic features and characteristics are presented. In this device, effects related to the lateral conduction in MIS tunnel structures are implemented. The device is featured by very simple processing, and shows promise in a variety of applications, including very large scale integration high speed IC's.     

Analytical integration of small-signal transport equations in an MIS structure at flat-band condition

The small-signal transport equations are solved analytically in a homogeneously doped MIS structure at flat-band condition. We can establish exact expressions of ac carrier density, electric field, and potential distributions in the MIS structure for any frequency. The plot of these expressions, in the frequency range from 10^-3to 10⁹Hz, proves the existence of majority and minority modes. A complete impedance expression is sufficient to determine all equivalent circuit components of the MIS structure at flat-band condition. The proposed method is valid for any bulk lifetime of carriers and for any semiconductor thickness.     

Analysis of printed transmission lines for monolithic integrated circuits

Planar transmission lines formed with MIS and Schottky barrier contacts are analysed based on the spectral domain technique. Depending on the frequency and the resistivity of the substrates, three different types of fundamental modes are predicted. The calculated slow-wave factors and attenuation constants agree well with experimental results.     

Finite Element Analysis of Lossy Waveguides-Application to Microstrip Lines on Semiconductor Substrate

The development of Maxwell's equations is made considering the electromagnetic fields as vector distributions. With the aid of the finite element method, an analysis of lossy shielded inhomogenous waveguides of arbitrary shape is described. To solve the complex matrix system an iterative procedure is presented. The method is applied to study the propagation on MIS or Schottky contact microstrip lines.     

Effect of minority carrier injection on lateral current in MIS tunnel structures

In this work it is shown that the MIS structure with an ultra-thin $\text{(20}\text{A}\text{?}\text{< x}{}_{\mathrm{i}}\text{< 40}\text{A}\text{?}\text{)}$ oxide is distinguished by a unique mechanism of lateral conduction. The flow of the lateral current between the two metal electrodes formed on the surface of an ultra-thin silicon dioxide is found to take place through the silicon substrate and the two non-equilibrium MIS tunnel diodes formed by the metal electrodes, the ultra-thin oxide, and the silicon. One of these diodes is forward biased and the other reverse biased. It is shown that the main limitation to the lateral current comes from the reverse biased diode. A structure is proposed in which such a lateral current can be efficiently controlled by the injection of minority carriers from the gate of an appropriately formed, conventional MIS tunnel diode into the depletion region of the reverse biased diode, so limiting the lateral current. Various physical phenomena related to this effect are studied and discussed.The MIS lateral tunnel structure considered in this work was fabricated in order to investigate the influence of minority carrier injection on the lateral conduction in MIS tunnel devices. However, the ideas proposed in this work can be developed into useful device structures.     

Identification and elimination of cardiac contribution insingle-trial magnetoencephalographic signals

A two-step method for identification and elimination of the cardiac contribution in single-trial magnetoencephalographic (MEG) signals is proposed. In the first step, the mean interfering signal (MIS) in one period is estimated by QRS-synchronous averaging of the raw MEG data. In the second step, a QRS-synchronous segmentation of the MEG signals is performed and each signal segment is Gram-Schmidt orthogonalized with the MIS. The above method is applied both to artificial and real MEG data. In each case the heart interference is all but eliminated whereas the components of interest, generated by the brain, remain almost unaffected     

Quasi-TEM Analysis of "Slow-Wave" Mode Propagation on Coplanar Microstructure MIS Transmission Lines

We present a simple quasi-TEM analysis of "slow-wave" mode propagation on micron-size coplanar MIS transmission lines on heavily doped semiconductors and compare theoretical results with measurements on four such structures at frequencies from 1.0 to 12.4 GHz. Excellent agreement is found, which shows that the "slow-wave" mode propagating on these transmission lines is, in fact, a quasi-TEM mode. Relatively low-loss propagation along with significant wavelength reduction is observed. Conduction losses of the metal, which have been tacitly ignored in previously published "full-wave" treatments of "slow-wave" mode propagation, are included in the theory and are shown to dominate the attenuation at frequencies below 25 GHz and to still be significant at frequencies up to at least 100 GHz.     

A pinhole model for metal-insulator-semiconductor solar cells

Based upon a consideration of the standard theory of MIS solar cells and the experimental results on such devices, the concept of tunneling through the thin insulating layer as the controlling mechanism is rejected. In place of the tunneling mechanism the concept of parallel Schottky diodes through pinholes in the insulator is proposed. The mathematical formulation fits this proposal. The characteristics and limits of efficiency expected for such a pinhole MIS are explored and found to be in good accord with existing results on experimental diodes. The equations needed to specify the density and size of the pinholes needed for optimal efficiency are formulated but not solved. A suggestion to test the hypothesis by artificially producing pinhole devices is proposed.     

Low-loss slow-wave propagation along a microstructure transmission line on a silicon surface

We report observations of relatively low-loss propagation in the frequency range of 1.0 to 12.4 GHz using a micrometer-size coplanar MIS transmission line fabricated on a heavily doped N + silicon surface. This low-loss mode of propagation is found to be accompanied by significant wavelength reduction which suggests that such lines may be useful as transmission media for distributed components in silicon monolithic microwave integrated circuits (MMICs).