Application of the transmission line equivalent circuit model to the analysis of the PN junction admittance under d.c. bias

Exact non-equilibrium one-energy-level numerical solutions of the admittance of a p+n junction are obtained from the nonuniform transmission line equivalent circuit model. Capacitance and conductance curves for equilibrium and reverse-biased gold-doped silicon diode are calculated using experimental values of emission and capture rates. Comparisons between theoretical and experimental frequency dependences of the admittance using new experimental capture rates show good agreements over a wide range of reverse bias.     

The equivalent circuit model in solid-state electronics—Part II: The multiple energy level impurity centers

In this paper, the equivalent circuit of a defect center with multiple energy levels in a semiconductor is formulated and applied to the calculation of the characteristic time constants of the multiple energy level system. Detailed numerical example of gold-doped silicon is given, including the constant characteristic time constant contour maps. The steady-state charge distribution ratio RN= Ns+1/Ns(s = charge state of the center) and recombination rate ratio RR(s) = RSS(s = ½)/(RSS(s-½) diagrams are developed and applied to the numerical calculations of the steady-state recombination and generation rate of electrons and holes in gold-doped silicon.     

Frequency dependence of the reverse-biased capacitance of gold-doped silicon P+N step junctions

The experimentally observed frequency dependences of the reverse-biased capacitance of gold-doped silicon step junctions over the frequency range from 10 cps to 30 Mc are found to be in agreement with a simple physical model which takes into account the charge condition and the charging and discharging time constant of the deep-gold acceptor level in the transition region of the junction. Analysis based on the simple physical model provides explicit theoretical formulas for the junction capacitance at low- and high-frequency limits which show that the high-frequency capacitance under reverse bias is approximately proportional tosqrt{N_{D} - N_{Au}}and is considerably reduced below the low frequency or dc capacitance if the donors are nearly compensated by the gold. The frequency effect is important for deep energy level impurities and becomes negligible if the impurity level is at or near the band edges. The presence of gold, however, has negligible effect on the avalanche breakdown voltage ifN_{Au} < N_{D}.     

Small-signal impedance of gold-doped P+-N-N+silicon diodes

Experimental results of impedance measurements on a long-base, gold-doped silicon diode show a substantial inductive effect. Various terminal characteristics are given and discussed with respect to possible contributing mechanisms.     

Large-Signal Silicon and Germanium Avalanche-Diode Characteristics

A technique for measurement of the large-signal single-frequency microwave amplifier admittance of avalanche diodes is described, and results are presented for silicon and germanium avalanche diodes. Single-frequency amplifier operation can provide a unique characterization of diode-admittance variation with RF drive for diodes operated near the optimum transit angle (the case in which all harmonic voltages are negligibly small compared to the fundamental). Such characterization is useful for predicting diode performance for circuits in which the harmonic voltages are not large enough to have an appreciable effect on the diode admittance at the fundamental frequency. A process of matching quadratic forms to the above admittance data which may be used for calculation of diode terminal admittance and power output is discussed. The usefulness of the measurement technique is illustrated by the agreement of the calculated maximum power output with the measured power output in a single-transformer coaxial circuit. The corresponding circuit admittance may be used for circuit-design purposes and for evaluating variations in diode-assembly techniques. The ability to obtain the diode equivalent circuit as a function of incident power allows studies in the design of the associated semiconductor device. For example, one has the capability of obtaining an accurate single-frequency large-signal model near the optimum transit angle, a model which can be studied without building a circuit. With this model it is possible to carry out optimization procedures at considerable savings of time and money.     

A nonlinear lumped network model of semiconductor devices with consideration of recombination kinetics

A nonlinear lumped network model of semiconductor devices with consideration of recombination kinetics is developed. A distributed system, based on a set of recombination kinetic equations for the multiple energy level centers, in addition to continuity, current flow relationships, and Poisson's equation, is shown to be approximated by a lumped RC network. As an example of application, the forward characteristics of a gold-doped silicon diode are calculated. The calculated results are found to be in good agreement with the experimental results within the range where the recombination current through gold centers is dominant.     

Characteristics of TIL GTO thyristors using no lifetime killers

The investigation reported in this work was focused on the main characteristics of the recently developed two interdigitation level (TIL) gate turn-off (GTO) thyristors, which use neither lifetime killers nor anode shorts. The advantages of these TIL GTO's with low on-state losses are outlined in comparison with their identical, yet gold-doped, counterparts. It is shown that, except for the turn-off time, the main electrical characteristics of TIL GTO's using no induced recombination centers are superior to those of similar gold-doped devices. The current-handling capability of the former under tough electrothermal ratings is also better than that of gold-doped devices up to a commutation frequency of 5 kHz. The results of this work demonstrated that sought-for benefits could be obtained in TIL GTO's which use neither induced recombination centers nor anode shorts.     

A Theoretical Study of the High-Frequency Performance of a Schottky-Barrier Field-Effect Transistor Fabricated on a High-Resistivity Substrate

The short-circuit admittance parameters for a silicon Schottky-barrier field-effect transistor (SBFET) fabricated on a high-resistivity substrate are calculated from first principles ignoring the effects of minority carriers. The calculations show the maximum frequency of oscillation for a device with a 1-/spl mu/m gate to be 17.9 GHz, neglecting the parasitic associated with the contact metallizations, and 14.7 GHz when the parasitic are included. In order to describe the dynamic behavior of the device, the static properties must first be obtained. The simultaneous solution of Poisson's equation and the continuity equation, both in two dimensions, gives the static charge and potential distribution in the device. The effects of a field-dependent mobility are included in the continuity equation. Using the results of static two-dimensional solutions, a one-dimensional device model is developed that permits the dynamic device behavior to be described by a one-dimensional linear ordinary differential equation. By solving this equation under appropriate boundary conditions, the device y parameters are found as functions of frequency. Calculated results are shown to be in good agreement with published experimental data.     

The use of multiple internal reflection on extrinsic silicon infrared detection

The sensitivity of a silicon extrinsic infrared detector is enhanced by increasing the absorption path by multiple internal reflection utilizing V-grooves on a [100]-oriented silicon wafer for light coupling. Planar detectors were fabricated with gold-doped silicon as a prototype study, in which the spectral response, the influences of temperature, and the photoconductive detector quantum efficiency were characterized. The result indicates that the peak of the photoconductive spectrum is located at 0.9 eV, which is equal to 1.67 times the threshold for extrinsic photoconduction, as generally expected from the theoretical calculations.     

Computer-Aided Large-Signal Measurement of IMPATT-Diode Electronic Admittance

A technique for the measurement of the Iarge-signal electronic admittance of IMPATT diodes as a function of frequency and RF voltage level using the network analyzer is described. The method de-embeds the admittance of the active region of the device from the mounting and measurement circuitry without physical disturbance of the diode. The small series resistance of the diode at breakdown is included in the embedding network together with the mount and diode package parameters. The determination of transformation networks between the measurement port and the active chip through a simple calibration procedure, a knowledge of the diode admittance below breakdown, and computer-aided optimization constitute the de-embedding procedure. Experimental electronic admittance curves are given for a low-power (100-mW) silicon IMPATT diode in the frequency range 5.7-6.5 GHz and with RF voltage levels applied across the active chip in the range 0-24 V, with an estimated error of less than 20 percent (typically 5 percent) in admittance values.     

A theoretical explanation of the carrier lifetime as a function of the injection level in gold-doped silicon

An expression for the recombination rate in gold-doped silicon is derived taking into account both gold energy levels. This formula shows that the dominant energy level under high-injection conditions is not the midgap gold acceptor, but the gold donor level. The high-low injection lifetime ratio calculated with the derived expression is in good agreement with measured values. This indicates that lifetime and capture cross section measurements are consistent with each other. The relation between gold concentration and high-injection lifetime is calculated. The relative density of the neutral and the negatively and positively charged traps is shown as a function of the carrier injection level.     

Microwave Characterization of Silicon BARITT Diodes Under Large-Signal Conditions

Experimental measurements of the small- and large-signal admittance of a silicon BARITT diode are reported. The structural characteristics of the devices are also reported, so that the results provide a basis for evaluating the Iarge-signal analyses of BARITT diodes. A lumped-element frequency-independent equivalent circuit is proposed to represent the terminal characteristics of the device over a broad-frequency range, and is verified by comparison with the measured admittances. Simple approximations are given to describe the dependence of the device admittance on the three operating point parameters: dc bias current, signal frequency, and RF signal level.     

Single injection, double injection and negative resistance in gold-doped high-resistivity silicon

A simplified explanation is given for negative resistance in a semiconductor containing deep-lying donor and acceptor levels. A simple equation is derived for the breakover voltage and is verified by experimental studies of single and double-injection currents in gold-doped silicon.     

The effect of injecting contacts on avalanche diode performance

Metal-semiconductor contact injection on the junction side of diffused-mesa avalanche diodes has been found to have a significant effect on the performance of these diodes as oscillators. A minority carrier injection ratio of 6 percent reduces the efficiency of what would be 9 percent efficient diodes to less than 1 percent and increases the FM noise by a factor of 2 as tested in a 6-GHz oscillator circuit. The dependence of the minority carrier injection ratio of the metal-semiconductor barrier upon current density has been measured and quantitatively modeled. Calculated values of diode admittance, including the effects of injection at the contact, are shown to be in agreement with measured values of both small-signal diode admittance versus frequency and large-signal diode admittance versus RF voltage. Germanium avalanche diodes with low-minority carrier injection contacts have demonstrated CW oscillation efficiencies greater than 9 percent at 6 GHz. The realization of low-injection contacts is shown to be a requirement for achievement of high-efficiency avalanche oscillation.     

An experimental investigation on the nature of reverse current of silicon power pn-junctions

At this time, little importance is given to the surface component of reverse leakage current of silicon pn-junctions although reliability issues reveal device blocking weakness when performing at high voltage and temperature. Junctions which have almost the same perimeter but different area have been realized and their reverse current has been measured at room temperature and high temperature both for standard recovery and fast recovery (gold-doped or electron irradiated) pn-junctions. It is shown that for standard recovery junctions the surface component of the reverse current is the primary component from room temperature up to above 150/spl deg/C and has influence on reaching high permissible working voltages. For gold-doped or electron irradiated junctions, the bulk component is dominant at high junction temperature, but it is shown that a comparatively negligible surface component can impose lower reverse working voltages or lower junction operation temperature. The surface component may be a cause of limitation on the operation of power silicon diodes at high reverse voltage above 175-200/spl deg/C junction temperature.     

Accurate closed-form expressions for the frequency-dependent line parameters of on-chip interconnects on lossy silicon substrate

Accurate closed-form expressions for the complete frequency-dependent R, L, G, C line parameters of microstrip lines on lossy silicon substrate are presented. The closed-form expressions for the frequency-dependent series impedance parameters are obtained using a complex image method. The frequency-dependent shunt admittance parameters are expressed in closed form in terms of the shunt capacitances obtained in the low and high frequency limits. The proposed closed-form solutions are shown to be in good agreement with the electromagnetic solutions.     

Experimental characterization of gold-doped infrared-sensing MOSFET's

The operation of a new type of infrared photon detector is described. This device is a gold-doped n-channel MOSFET that employs impurity photoionization to modulate its drain-to-source conductance. A simple mathematical model is developed whereby the infrared-sensing MOSFET (IRFET) can be analyzed, and experimental results that verify the model are provided. The near-infrared, i.e., wavelengths from 1.38 to 3.54 µm, response of gold impurity centers in the space-charge region behind the strong surface inversion layer of a MOSFET is shown to correspond to the characteristics observed previously by other authors for the gold centers in bulk silicon. A static read-only memory capability and high responsivity, typically 4 mW/µJ, are the most significant IRFET characteristics. Applications in large-scale-integrated imaging arrays are anticipated.     

Photodetection using photomagnetoelectric and Dember effects in gold-doped silicon

Photodetection in the visible and near IR wavelength region using photomagneto-electric and Dember effects in gold-doped silicon has been demonstrated in this note. Response time trof 0.2 µs and noise equivalent power (NEP) of 6 × 10^-10for a photomagnetoelectric (PME) cell, and tr< 0.03 µs and NEP = 2.5 × 10^-10for a Dember cell, were obtained from the present results.     

Prolate spheroidal antennas in isotropic plasma media

The problems of a gap-excited finite-sized prolate spheroidal antenna, with and without a confocal prolate spheroidal vacuum sheath, operated in a uniform cold and in a uniform warm lossy plasma medium, have been considered by applying boundary value problem techniques. The dependence of the input admittance, the current distribution, and the radiation pattern, upon the collision frequency, the electron temperature, the length of the antenna, the length-to-radius ratio for the antenna, the ratio of the plasma frequency to the operating frequency, and the thickness of a vacuum sheath have been investigated. Admittance curves are given from which the input admittance of a finite linear antenna can be estimated for a wide range of operating conditions and length-to-radius ratios. Conductance and susceptance maxima, dependent upon the vacuum sheath thickness, have been observed when using the cold plasma model foromega < omega_{p}. When using the warm plasma model in conjunction with the boundary condition that the normal component of the fluid velocity is zero at the antenna surface and at the vacuum sheath surface, the radiation resistance of the antenna is increased significantly for the parameters considered.