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     

Transient Behavior of the ${hbox{a}}{hbox{-}}{hbox{Si}}:{hbox{H/Si}}_{3}{hbox{N}}_{4}$ MIS Capacitor and Its Impact on Image Quality of AMLCDs Addressed by a-Si:H Thin-Film Transistors

Transient behavior of the a-Si:H/Si₃N₄ metal-insulator-semiconductor (MIS) capacitor and its relationship to the performance of a-Si:H based active-matrix liquid crystal displays (AMLCDs) have been analyzed in detail. A relatively slow voltage decay whose time constant is comparable to the frame period of the LCD is observed after applying a voltage pulse that drives the MIS capacitor into the electron accumulation. The voltage decay is due to electron emission from the localized states at the a-Si:H/Si₃N₄ interface. It is also found that this voltage transient results in a shift in the optimum common voltage for the liquid crystal pixel by changing the temperature and light exposure when an MIS-type capacitor is inserted between the pixel electrode and the adjacent gate bus-line as the storage capacitor. This shift in the optimum common voltage affects the image quality of AMLCDs through image sticking or flicker. A similar effect can occur even without an MIS-type storage capacitor in high resolution AMLCDs, where the gate-source parasitic capacitance of the thin-film transistor is comparable to the net capacitance of the pixel. It is important to take such transient effects of MIS capacitors into consideration in pixel designing     

Transient excitation of an antenna with a nonlinear load: Numerical and experimental results

A comparison of numerical and experimental results for the current flowing into a nonlinear diode load attached to the terminals of a receiving antenna for transient excitation is presented. It is shown that a simple nonlinear resistive model for the diode is not sufficient to obtain good agreement between the theoretical and experimental results. The diode model and numerical analysis are modified so as to permit the consideration of a junction capacitance. The resulting comparison of data is much better.     

A behavioral circuit simulation model for high-power GaAs Schottky diodes

This paper proposes a physically based behavioral circuit simulation model for high-power GaAs Schottky diodes which is valid over all regions of operation. No conditional statements are needed to define the regions of operation. A new and more accurate method of obtaining depletion capacitance model parameters from the measured capacitance values is proposed. A simple current- and temperature-dependent resistance model is used to model the nonlinear diode resistance as well as contact and packaging resistances. The validity of the model is demonstrated under various DC and transient switching conditions. Simulation results are compared with the experimental data obtained from a 200 V GaAs Schottky diode. The diode model is tested at various temperatures in different test circuits and the simulation results are shown to be in excellent agreement with the measured data under static and dynamic switching conditions. The model can be easily implemented in other circuit simulators.<>     

Small-signal performance of a quantum well diode

We study a small-signal performance of a quantum well (QW) diode with triangular emitter and collector barriers providing thermionic electron transport. Analytical expression for the QW diode admittance is obtained from the rigorous self-consistent small-signal analysis. Frequency dependence of the admittance is determined by a characteristic time of recharging of the QW, which is a strong function of temperature and parameters of the QW diode. Conductance as a function of temperature shows a local maximum corresponding to a resonance between a probe signal and recharging processes. Capacitance of the QW diode depends critically on the efficiency of the electron transport through the QW, and can significantly exceed all geometric capacitances associated with the device structure. Experimental data on conductance and capacitance of the QW diode as functions of temperature and frequency can be used to extract the parameters of the QW, such as QW recombination velocity, ionization energy, etc. Analytical analysis of transient currents in the QW diode allows a transparent explanation why an incremental charge-partitioning technique fails to calculate the capacitance even in the low-frequency limit     

Lumped-circuit representation of Gunn diodes in domain mode

It is shown that the lumped circuit that has been used to date to represent a Gunn diode with a steadily propagating domain cannot and does not properly account for the transient, and therefore, high-frequency behavior of a Gunn diode. We have derived the nodal equations that must be obeyed by any circuit that is to represent a Gunn diode with a steadily propagating domain under all conditions --small signal and large signal, sinusoidal steady state, and transient. The validity of the new circuit and the fact that the conventional circuit would give erroneous results under transient conditions have been checked by transient experiments on the computer simulated Gunn diode. It is also shown that the domain differential capacitance is approximately half of what is given by zero diffusion theory, a result first predicted by Kuru, Robson, and Kino, and the discrepency is accounted for by the nonzero width of the accumulation layer, and incomplete depletion in the depletion layer.     

Influence of illumination on MIS capacitances in the strong inversion region

A simple analysis is presented of the effect of illumination on MIS capacitance in the strong inversion region. The two mechanisms responsible for the increase of capacitance under illumination are described: the decrease of the time constant generation of the inversion layer, and the decrease of the space-charge region under illumination. The theoretical results are compared with the experimental data on silicon and tellurium MIS capacitances.     

Comments on “Negative capacitance effect in semiconductordevices” [by M. Ershov et al., with reply]

For original paper, see M. Ershov et al., ibid., vol. 45, pp. 2196-2206 (Oct. 1998). The original authors tried to interpret the negative capacitance (NC) phenomenon theoretically in physics. However, the commentators point out that the definition of capacitor from I=(G+jB) V used in the paper is not correct. Using an R-L-C resonance circuit they interpret the so-called NC, that is just an inductive effect. Instead of using the conventional R-C equivalent circuit model for a diode, one should use an R-C-L resonance circuit as the equivalent circuit for the diode. In reply, Ershov et al. assert that they proposed a convenient and physically sound approach to NC treatment based on transient current analysis and highlighted typical mistakes involved in NC interpretation. They refute the criticism of the definition of capacitance in terms of admittance made by the commentators     

Current transient spectroscopy: A high-sensitivity DLTS system

A deep-level transient spectrometer (DLTS) has been built that measures current transients, rather than the usual capacitance transients, in p-n junctions. The system was developed to optimize sensitivity for the study of low-concentration processing-induced defects. An analysis of its performance as a function of timing parameters is presented. A noise analysis of both capacitance and current transient measurement is presented, showing that neither method has an inherent sensitivity advantage, and that both should be capable of detection limits of about 10^-7to 10^-8of the shallow doping concentration. Noise measurements indicate that a detection limit of 10^-7times the doping has been obtained. Spectra of a processed p⁺-n diode with no intentional contamination show several defect levels in the 10^-5ND, or 10¹⁰cm^-3, range. Spectra of gold-doped p⁺-n diodes yield emission data in good agreement with accepted values.     

Investigation of both interface states spectrum and deep oxide states from differential isothermal transient spectroscopy

Metal/insulator/Si (MIS) structures using a high-permittivity (high-k) dielectric layer, here the perovskite compound SrTiO₃, are investigated by differential isothermal transient spectroscopy in order to study electronic states at interface and inside the oxide. The isothermal transient capacitance responses of these MIS capacitors, obtained at varying depletion bias voltages and recording times, are analysed by fast Fourier transform (FFT). Different values of the accumulation pulse duration may induce changes in the trapped charge, allowing identification of the various mechanisms for restoring thermodynamical equilibrium in the interface states. Thus, discrimination between the proper contribution of interfaces states and that of oxide deep states is evidenced. The effects of several post-annealing of the oxide layer onto the energy spectra are also described.     

A random noise reduction method for an amorphous siliconphotoconversion layer overlaid CCD imager

A novel random noise reduction (RNR) method, which can reduce random noise generated in a storage diode (SD), has been proposed and evaluated with a cell test element. The RNR cell structure features an RNR transistor with a second storage diode, which is inserted between the SD and a vertical CCD (V-CCD). The RNR transistor controls the transfer channel potential and suppresses the random noise generated in the SD. Net first storage diode capacitance with the RNR transistor can be reduced down to (C_f×C_a)/(C_f+m×C_a ), where C_f is the second storage diode capacitance, C _a is the first storage diode capacitance, and m is the channel potential modulation factor. Experimentally, the RNR cell can reduce the random noise in the SD from 42 electrons [r.m.s.] down to 18 electrons [r.m.s.] for the SD capacitance of 5 fF. This makes it possible for the photoconversion layer overlaid CCD imager with the RNR cells to reproduce video images with a high S/N ratio     

Automated measurement and analysis of MIS interfaces in narrow-bandgap semiconductors

A computerized system for simultaneous measurement of high-frequency and quasi-static MIS capacitance is described. The importance of this simultaneity in the application of various analysis methods to MIS devices in narrow-bandgap semiconductors is discussed. Results on the interfaces of mercury-cadmium-telluride with zinc sulfide and anodic oxide are given.     

A physics based model for the RTD quantum capacitance

A simple derivation of the form for the compact model of the quantum capacitance in a resonant tunneling diode (RTD) is presented. The quantum capacitance is shown to reduce the resistive cutoff frequency. The implementation of the model into SPICE is described. The distorting effect of the strongly nonlinear quantum capacitance on an oscillator circuit is demonstrated in a SPICE simulation. The nonlinearity becomes important for the highest frequency applications when the RTD capacitance is comparable to the capacitance in the rest of the circuit.     

A dynamic model of the p-n-n+ step recovery diodes for the numerical analysis of pulse circuits

A new p-n-n⁺ diode model for circuit transient analysis is developed. In contrast to existing circuit models, this model reflects all step-recovery diode (SRD) effects during switching on and off, including “ramp” of slow recovery phase. It is accomplished by taking into account the dynamic physical phenomena in the p-n-n⁺ diodes when switched. A non-linear dynamic diffusion capacitance of the diode model is determined by the dependence of the instantaneous base charge on the instantaneous diode voltage.The accuracy of the presented model is verified by comparison of the calculated and measured wave forms of some pulse circuits.The present model has been proved to be more accurate than SRD models previously published.     

Accurate Determination of Varactor Resistance at UHF and Its Relation to Parametric Amplifier Noise Temperature

A thorough investigation is made on the frequency-dependent properties of a varactor diode loss resistance at UHF. The variation of the losses with frequency in a varactor diode mounted cavity has been theoretically investigated, and it is shown that the previously reported inverse-squared frequency dependence of the varactor loss resistance can be attributed to the distributed cavity losses transformed across the varactor diode. A new measurement technique is introduced in which the circuit losses are first matched to the input line instead of the varactor loss resistance as an application of the relative impedance method. Measurements carried out with this technique for five different varactor diodes showed that the loss resistances of these diodes are not frequency dependent. It is also shown that the choice of the varactor diode capacitance plays an important role on the parametric amplifier noise temperature at UHF. In an experimental parametric amplifier the effect of varactor diode capacitance on the noise temperature has been demonstrated. It has been theoretically and experimentally shown that, generally, varactor diodes having higher capacitances result in better noise temperature at UHF.     

Concentration profiles of recombination centers in semiconductor junctions evaluated from capacitance transients

The effect of stationary charges trapped in the region near the p-n boundary and in the edge region of a semiconductor junction space-charge layer on the evaluation of the concentration profiles of the recombination centers as well as doping impurities, from high-frequency capacitance transient data, is studied. Both the theory, its simplification for junctions with low concentration of recombination centers, and two experimental examples are given to illustrate the importance of the edge effect. One of the examples is an aluminum on n-Si Schottky diode with a very low concentration of process-induced donor trap, and the other is a phosphorus and gold diffused diode with a gold concentration about 20 percent of the boron concentration.     

A novel beam lead GaAs Schottky-barrier diode fabricated by using thick polyimide film

A novel beam lead GaAs Schottky-barrier mixer diode with high performance has been developed for use in super high frequency (SHF) receiving system. The parasitic capacitance of the diode has been reduced to 0.03 pF by using thick polyimide insulating film formed by improved etching techniques. The series resistance has been lowered to 0.5 Ω by a liquid-phase double epitaxial method of growing an n-n⁺⁺active layer on an n⁺wafer. The total diode capacitance at zero bias has been lowered to 0.15 pF using a 10-µm junction diameter. An n factor of less than 1.10 was obtained. The calculated cutoff frequency including parasitic capacitance exceeds 2000 GHz. Several reliability tests including temperature cycling in high humidity show good results. In an SHF downconverter consisting of a waveguide which contains a planar circuit, the diode was attached to the planar circuit by means of an intermediate plate, despite the small diode dimensions of 0.75 mm by 0.22 mm. An overall noise figure (NF) as low as 4.3 dB, and conversion loss as low as 3.0 dB were achieved at 12 GHz (IF range of 290-470 MHz and IF amplifier NF of 1.5 dB). These values are shown to be satisfactory for application to a low-noise receiving system for satellite TV broadcasting.     

Interdigitated pn junction device with novel capacitance/voltage characteristic, ultralow capacitance and low punch-through voltage

The first demonstration of the recently disclosed channelling diode is reported. The structure combines important and unique features which can be used for a large variety of applications. The diode exhibits a novel capacitance/voltage characteristic; large capacitance variations (1 pF) have been achieved over a small voltage range. Operated as a PIN diode the device has an ultralow capacitance (0.05 pF) and a low punch-through voltage (2?3 V). This small capacitance is largely independent of the detector area and of the doping of the layers. These features are important for ultralow noise PINFET receiver applications.     

Electrical characteristics of GaAs MIS Schottky diodes

The current-voltage (I-V) and capacitance-voltage (C-V) characteristics of GaAs metal-insulator-semiconductor (MIS) Schottky barrier diodes are investigated over a wide temperature range and compared with MS diodes. The effects of the insulating layer on barrier height and carrier transport are delineated by an activation energy analysis. Excess currents observed at low forward and reverse bias have also been analyzed and their cause identified. A capacitance anomaly consistently noticed in MIS Schottky barriers is resolved by stipulating a non-uniform interfacial layer, and a self-consistent model of the GaAs MIS Schottky barrier is developed by analyzing I-V and C-V data of both MIS and MS diodes.