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We have obtained spectra for the LO phonon mode by Raman scattering associated with surface quantization of the hole states in the depletion layer of highly doped n -type GaAs samples. When semi-transparent metal contacts are employed, the zone-center LO peak shifts to higher frequency due to plasmon-phonon interaction. The observed effects are not sensitive to the types of metal. The presence of the plasmon mode is thought to be due to the steady-state carrier injection from the incident laser light. The position of the peak is used to estimate the surface recombination rate of the excited electron-hole pairs.

If a GaAs diode is biased above threshold and if the doping N exceeds a critical value Np of about 1021 m−3, the instability due to negative differential conductivity (NDC) can settle into a stationary anode layer. This layer remains when the voltage is subsequently reduced below threshold, provided that N is sufficiently uniform near the anode. A diode in which the doping or the cross section increases toward the anode exhibits static negative differential resistance. When a diode with a small anode overdoping is biased above threshold, a depletion layer forms at the anode and, if N > Np, propagates towards the cathode. The simulation of negative conductance at 50 GHz in the LSA mode raises the possibility of high‐efficiency amplification at very high frequencies by parastable diodes.

Ion‐implanted MOS transistors were fabricated and their electrical characteristics, such as threshold voltage, effective mobility, etc., were measured. In the 11B+‐implanted p‐channel case, threshold voltage VT can be shifted linearly with implant dose. These shifts ΔVT were entirely determined by the net dose entering silicon. On the other hand, in the 11B+‐implanted n‐channel case, threshold voltage shift ΔVT varied sublinearly with dose and showed strong dose profile dependence. The profiles were varied with changing implantation energies and annealing times. These results can be interpreted in accordance with the rapid decrease of the maximum surface depletion layer Xd max with the implant dose increase. Numerical calculations of threshold voltage shifts accounting for nonuniformly implanted profiles were compared with observed results. Good agreement was obtained. Effective mobilities μeff of 11B+‐implanted p ‐ and n ‐channel MOS transistors also showed different dose dependences. In the low‐dose reg...

The small signal admittance, Y, of a junction device, in the presence of deep lying majority carrier traps, is obtained as a solution to a simple differential equation (dC/dχ) = (C2/e)−(ρac/ψac), where C Y/jω is the complex capacitance, x is the distance within the depletion region from the neutral bulk semiconductor, ρac is the a.c. incremental change in charge density at χ when the bias is incremented by ψac. This equation can be numerically integrated with one boundary condition, the flat band capacitance of the bulk semiconductor. An analytic solution to the above differential equation is possible over a wide frequency range without the use of a truncated space charge approximation. The admittance of one half of a junction device can then be modelled by a 3p + 1 lumped element equivalent circuit involving 3p + 2 device parameters, where p is the number of species of deep lying majority carrier traps that are virtually unionized in the bulk. These circuit elements bear simple direct relationships to the deep level parameters. Impedance vs frequency measurements at a single bias and temperature yield only 2p + 1 equations and are not sufficient to define the elements uniquely. One therefore needs p + 1 additional equations for a unique synthesis. We also show how additional equations can be obtained from impedance vs voltage or temperature measurements.

Measurements of emission rates and majority carrier capture cross-sections of Au, Pt, Pd and Rh centres in silicon are reported, and the activation energies associated with the different levels of these centres are determined. Where appropriate, our results are compared with values reported in the literature; other results have not been previously reported. The measurement depends on the emission and capture of majority carriers on the centres in the depletion layer of a p-n junction or Schottky barrier. The change in charge state of the centres is monitored by measuring the change in reverse bias applied to the junction necessary to keep the junction capacitance constant. The advantage of this technique, compared with the usual method of keeping the bias voltage constant and measuring the change in capacitance, is demonstrated.

A RC-equivalent circuit for a MOS transistor, for low frequency and small alternating signals is proposed. It is shown, that it is possible under some experimental conditions to infer from two series of measurements, one in inversion mode the other in accumulation mode, the total capacitance of the depletion layer which lies in the substrate under the inversion channel. The concentration of ionized donors in the substrate is determined by the variation of this capacitance with the bias source to substrate. On propose un schema RC equivalent au transistor MOS pour des signaux alternatifs de frequence moyenne et de faible amplitude. On montre alors que, dans certaines conditions experimentales, on peut deduire de deux series de mesures, l'une en inversion, l'autre en accumulation, la capacite globale de la zone d'appauvrissement situee dans le substrat sous le canal d'inversion. On deduit la concentration en donneurs ionises dans le substrat des variations de cette capacite avec la polarisation substrat–source.

We have solved Maxwell's equations for the fields localized near the surface of a doped semiconductor possessing either a depletion layer, an accumulation layer, or an inversion layer. We present the dispersion relation for the frequency of the surface plasmon polariton as a function of the wave vector parallel to the surface for each of the three cases. The effect of the space charge at the surface is taken into account by dividing the surface region into layers and assuming a linear position dependence for the free-carrier concentration and the local dielectric constant within each layer. We have found the solution for the fields within each layer and have satisfied the boundary conditions for the normal and tangential components of the fields at each interface between layers. We show that the features of the dispersion curve can be used to obtain information about the space-charge region. For illustration, we compare our calculations with measured dispersion curves of $n$-type InSb.

Ellipsometry has been used to measure the thickness of the residual film on the germanium surface after etching. Residual film thicknesses of 4 A, 20 A and 500 A are obtained for the 10:1, 3:1 and 1:10 etches, respectively. A single detector was processed a total of 63 times using a variety of surface treatments. This study showed high breakdown voltage could be obtained with a variety of etches, but that the time the detector remains in the quenching solution should be minimized. The edge of the depletion region was scanned with a collimated 60 kV ? source after each surface treatment. The two scan results that could reprevroducibly be obtained were the type C, obtained with a 3:1 or 10:1 etch, a water quench, a brief evacuation and a rapid cool down, and the type B obtained using the same procedure with a 1:10 etch. The type C scan can be eliminated by heating in vacuum and restored by exposure to room air suggesting that it is caused by water vapor adsorbed on the surface. The type C scan is believed to result from hole trapping at the surface of the depletion region. An external electric field has been used to increase the breakdown voltage of the detector.

The space charge conductance and bulk conductivity of epitaxial {111} and {200} films of AgCl with thickness in the 1-μ range has been measured. Interstitial silver ions predominate in concentration within the space charge layer and in the bulk, but are present in concentration roughly 1 10 the concentration present in similar AgBr films. Values of the free energy change required for interstitial formation (0·56 eV) and vacancy formation (0·69 eV) were obtained for generation at the surface sites on a {111} film; similar values are reported for {200} films, although the value depends somewhat on the substrate. The concentration of ionic carriers present in the AgCl thin films is 100–1000 times greater than in bulk single crystals.

An improvement is made on the technique of determining the impurity density in a semiconductor from C-V measurements. It is shown that the average impurity density inside the depletion region plays a major part in precise determination of shallow and deep impurity profiles. Measurements of time variation of the bias voltage with the capacitance unchanged are useful for deep levels, and make it feasible to gain knowledge of their energy levels and density profiles simultaneously. These techniques are successfully applied to n-type VPE GaAs on Cr-doped semi-insulating substrates.

Surface breakdown in silicon planar junctions is analysed with emphasis on the evaluation of the critical field (i.e., the maximum electric field within the depletion region at breakdown). This parameter is determined by a computer-aided experimental procedure consisting in relaxation field calculations with boundary conditions governed by junction breakdown voltage (at given gate voltage) as measured on specially processed gate-controlled diodes. The idealization (infinite doping) of the highly doped side of the junction, encountered in previous works, has been eliminated. Values of the critical field determined are in the range of 1 × 10 6 V/cm (1·0 × 10 6 V/cm for 1·0 μm gate-oxide and 1·4 × 10 6 V/cm for 0·3 μm gate-oxide). These values are substantially higher than those estimated by other authors (5–6 × 10 5 V/cm) and are consistent with independent experimental findings on avalanche (hot-carrier) injection in silicon diodes.

Large signal photovoltage pulses, measured on real surfaces of high-resistivity p-type silicon as a function of excitation intensity and induced charge, show characteristic features, especially smooth minima in the negative pulses. It is shown how the results can be used for a determination of surface potentials (band bendings) and surface- or interface-state distributions. Comparisons between theoretically and experimentally determined photovoltages show that the exchange of charge carriers between surface states and space charge layer during electron-hole nonequilibrium was not negligible and has to be taken into account for an accurate determination of surface potentials. The influence of such trapping processes is analysed graphically and analytically for continuously distributed surface states and the modifications due to trapping are determined. It is shown that the bands become asymptotically flat for the limit of large excitation even when strong trapping in a system of continuously distributed surface states with arbitrarily large concentrations prevails.

Gated P + - N diodes in silicon were used to investigate the avalanche-injection of electrons into SiO 2 at high current densities. The acceptor concentration in the P + -region of the diodes was high in order to minimize surface depletion there by the relatively high positive gate voltage during the injection. Injection current densities up to 10 A/cm 2 were obtained. The oxide current vs. gate voltage characteristics are described quantitatively by a simple model in which the current is injection-limited. Hot electrons from the avalanche plasma in the junction lose energy by inelastic collisions and gain energy by drift in the surface potential. Both processes are assumed to occur in a layer of thickness equal to the surface depletion layer thickness in the P + -region. The temperature dependence of the injection current is ascribed to the temperature dependence of the energy loss term.

Experimental results are presented to support the contention that the light output of SiC electroluminescent diodes can be dominated by radiative tunneling over a wide temperature range. A spectral peak shift to higher photon energy with increasing junction voltage has been observed, as well as a temperature‐independent slope of the light intensity‐voltage curves. Both of these properties are characteristic of radiative tunneling. In addition, the value of the temperature‐independent slope agrees with that calculated from a simple tunneling model using data from capacitance measurements. An energy‐band scheme is proposed which leads to the tentative conclusion that the radiative recombination process is donor‐acceptor pair recombination of tunneling carriers in the depletion layer.

Preparation of silicon avalanche photodiodes by a planar method in epitaxial PP+ silicon slices limited charge collection to carriers generated in or close to the depletion region. Reducing the effective size of the zero-field absorption region surrounding the depletion region by this method, resulted in the output signal current of the device reproducing the input light pulse shape, within 15 ns. When illuminated with monochromatic radiation, the shot noise of a detector prepared in epitaxial material was less than that observed with a device fabricated in homogeneous material, due to the reduced signal current.

The characteristics of aluminumSi 3 N 4 GaAsP MIS capacitors are reported. High frequency C - V , and surface electroluminescence experiments have been conducted. It has been found that the generation rate of minority carriers in the surface space charge region is very low and the efficiency of the surface electroluminescence is high. Application of the MIS structures in displays based on surface electroluminescence is proposed and discussed.

A generalized model is developed for the electronic behavior of deep traps in a p‐n‐junction depletion region. The depletion region is shown to consist of two parts: (i) a space‐charge region which is totally depleted of free carriers and (ii) a transition region which is only partially depleted. The influence of this junction structure on free‐carrier profiling measurements is considered in detail for donor and acceptor traps with both homogeneous and inhomogeneous spatial distributions. Experimental observations of deep‐trap distributions produced by proton bombardment of n‐type silicon are analyzed within the framework of the model. Implications of the model in the measurement of junction capacitance transients and photocapacitance are considered in Appendices A‐C.

Multiplication processes have been investigated on Au–n-ZnSe Schottky diodes by optical injection of initiating carriers into the space charge region in the electric field range of 5.5 × 105 V/cm < F < 7 × 105 V/cm. Using the photoemission of electrons from the Au-contact over the metal–semiconductor barrier the pure electron-initiated multiplication factor Mn has been measured. However, the hole-initiated multiplication factor Mp by backside excitation of the diode with hv ≈ Eg could not be used since the hole diffusion length Lp has been found to be very small. But from theory it can be shown that Mp can be evaluated from the measured multiplication factors Mn and Mnp; Mnp represents the multiplication initiated simultaneously by electrons and holes in the space charge layer. On the basis of this method in the first order approximation Mn ≈ Mp. Applying the analytical approximations proposed by Okuto and Crowell to the measured field dependence of the ionization coefficient one arrives at a “mean free scattering length” λ ≈ 45 A, depending on the assumed mean threshold energy Ei. Es sind an Au–n-ZnSe Schottky-Dioden im Feldstarkebereich 5,5 × 105 V/cm < F < 7 × 105 V/cm Multiplikationsprozesse untersucht worden, wobei Primarladungstrager optisch in das Raumladungsgebiet injiziert werden. Der durch reine Elektroneninjektion bedingte Multiplikationsfaktor Mn ist gemessen worden, indem Elektronen durch Photoemission uber die Metall-Halbleiter-Barriere des Goldkontaktes injiziert worden sind. Der durch reine Locherinjektion bedingte Multiplikationsfaktor Mp konnte jedoch durch optische Anregung von der Ruckseite der Diode mit hv ≈ Eg nicht ermittelt werden, da sich die Locherdiffusionslange Lp als zu klein ergeben hat. Es last sich theoretisch jedoch zeigen, das Mp durch Messung der Multiplikationsfaktoren Mn und Mnp berechnet werden kann. Mnp entspricht einer Multiplikation, die simultan sowohl durch Elektronen als auch durch Locher in der Raumladungsschicht ausgelost wird. Mit dieser Methode erhalt man Mn ≈ Mp. Unter Anwendung der analytischen Naherungsausdrucke von Okuto und Crowell erhalt man aus der gemessenen Feldabhangigkeit des Ionisationskoeffizienten eine „mittlere freie Streulange” λ ≈ 45 A; diese hangt von der angenommenen mittleren Schwellenenergie Ei ab.

A theory of diode structure based on the formalism of the potential Ψ is presented. Expressions describing static and dynamic dependences of (p–n)-(l–h) diodes as well as resistors with two l–h junctions have been derived. The recombination of carriers within the junction depletion layer and on the interface of the junction is neglected. The formulae thus obtained proved to be in agreement with those derived by other authors for particular cases. [Russian Text Ignored]

Silicon p+n junctions heat treated at high temperatures (1200°C) for a long time (2–20 hr) and then quenched to room temperatures or below shows two deep donor levels (EC−264meV andEC−542meV) in the n-type side of the junction depletion layer which appear to originate from the same imperfection center. The concentration of these levels ranges from 1013 to 1014 cm−3. The junction leakage current comes from carrier generation at the deeper level in the depletion region. Phosphorus gettering was found ineffective in reducing the concentration of these quenched-in levels, but they are annealed out by very slow cooling (25°C/hr to 650°C then quench to room temperatures). The thermal emission and capture rates of electrons and holes at these levels are measured as a function of temperature and electric field by the junction high frequency capacitance and d.c. leakage current transient techniques. It is demonstrated that the detailed balance relationship does not hold. The origin of this double donor center is yet to be identified.

The reverse bias light emission originating at microplasmas was investigated in GaAs1-xPx diodes and compared with the forward bias emission. Both spectra were found to be almost identical and could be explained by the same radiative recombination processes. The presence of the strong electric field in the junction gave rise to the Franz-Keldysh effect manifested by the uniform shift (∼3 meV) of the reverse bias emission towards longer wavelengths with the Stark effect broadening the free-exciton emission peak P1. Measurement of the shift indicated that the electric field responsible for this, though high (∼103 V/cm), was considerably lower than that prevailing in the centre of the junction (∼5×105 V/cm). This pointed to recombination and the concomitant radiation occurring at the edge of the depletion region, the high field in the centre of the junction inhibiting the recombination of electron hole pairs.

Reaction schemes which give rise to spatial and temporal oscillations often involve an autocatalytic step, e.g., A ← B → 2B. The coupled reaction-diffusion equations for this reaction taking place in a closed system with A and B diffusing independently are solved using an extended WKB method, giving approximate analytical describing both the space and time evolution. An initial inhomegeneity in B is found to grow, with a depletion region being formed in front of the growth area because of back-diffusion. Lower limits are imposed on the width of the transient structure so formed because of the competition between reaction and diffusion. Qualitative experimental verification is observed under certain conditions in precipitation from supersaturated solutions.

Silicon surface barrier detectors have been irradiated with 0.5–2 MeV protons to observe the radiation damage effects appearing in electrical properties. The depletion layer capacitance against bias voltage has shown a plateau which is dependent on proton fluence and energy. This behavior is consistently explained by the proposed model in which the induced defects act as acceptors and compensate donor ions in the proton range. The effective number of defects is estimated to be about 0.2 per 1 MeV proton.

Impedance measurements on the n- and p-type GaAs electrode show that in both cases, a depletion region exists under reverse bias. The capacitive behaviour of n-type GaAs is relatively simple and allows to determine the position of the conduction and valence band edge at the surface with respect to a reference electrode level. From the pH-dependence of this position, it follows that an acid-base equilibrium is established at the GaAs surface. The impedance behaviour of p-type GaAs is rather complex, and is interpreted on the basis of a model in which localized levels at large energy distance from the valence band edge are involved. The results indicate that the position of the band edges at the surface of GaAs in contact with a given electrolyte is essentially the same for n- and p-type material. The data obtained permit to explain qualitatively the electrochemical reactivity of the hexacyanoferrate (III) ion as well as the lack of reactivity of certain reducing agents at the GaAs electrode.

The optical and electronic properties of single crystal Cu2S-CdS photovoltaic cells were investigated. In these cells trapped charge near the interface which is manifested by a persistent increase in junction capacitance (the photocapacitance) plays a significant role in determining the carrier transport properties. It was found that the severe degradation in short-circuit current observed in heat-treated cells can be separated into two components: (1) a relatively small thermal component occurring on heat-treatment in the dark, and (2) a much larger degradation caused by exposure to light at room temperature. By a short additional heat-treatment above approximately 100 C the cell can be completely restored to its condition before the optically caused degradation with no effect on the depletion layer width.

A decrease in the counting rate and charge collection efficiency of p-type CdTe gamma-ray detectors, starting from the time of first application of the electric field, has been observed. Momentary removal of the bias returns the detector to its initial state. The behavior can be understood in terms of deep acceptors which detrap holes and decrease the thickness of the space charge region. Non-polarizing detectors can be made by using either high work function contacts with appropriate surface preparation or by periodic removal of the bias.

A one-dimensional model of a buried channel CCD is presented. The potential equations, using the depletion region approximation are solved for a range of doping levels and stored charge. In this way values of device capacitance are calculated. It is shown that for a device with uniform layer and substrate dopings, the equations have an analytic solution. These solutions take a rather complicated form, but have a simple geometrical representation. A geometrical construction, based on field plots, is given. This construction may be used in the study of more general doping profiles.

A new non-volatile charge storage device is described. The floating gate avalanche injection MOS (FAMOS) structure is a p -channel silicon gate field effect transistor in which no electric contact is made to the silicon gate. It combines the floating gate concept with avalanche injection of electrons from the surface depletion region of a p - n junction to yield reproducible charging characteristics with long term storage retention.

The depletion layer capacitance of n-type gallium arsenide was measured as a function of its anodic potential in an electrochemical cell. It was shown that these measurements can lead to accurate values of carrier concentration, and are compatible with stripping by electrochemical dissolution, provided that surface area is preserved. The experimental conditions required to maintain the electrolyte-semiconductor contact area constant, are described. Also, it is shown that excursions into regions outside those specified lead to significant enhancement of capacity (via real area increase). Under these conditions the carrier concentration can no longer be obtained but much can be learnt about the internal structure of the material.

The effects of radiation damage on the current-voltage characteristics of silicon p-n diodes are studied. Radiation damage is introduced by the implantation of carbon ions into the depletion region of the device. The physical properties of the damage centres are examined by means of thermally stimulated current (T. S. C.) measurements, and by the measurement of the temperature dependence of the reverse leakage. The results at low implantation doses are explained by means of a single level Shockley-Read-Hall model, while at higher doses charge compensation effects are introduced. Capacitance-voltage measurements are used as a means of verifying these conclusions, and further useful data is obtained from the results of low temperature annealing experiments.

The D. C. conductivity of human bone is investigated in the region of moderately high fields. A temperature range extending from 30°-60°C is scanned. Results indicate (1) an increase in conductivity with increasing temperature, and (2) the occurrence of a space charge region at relatively low fields. It is pointed out that electronic conduction along with the protonic conduction is responsible for the charge transport in bone.

Heterojunction optical waveguide modulators in which the modulated region may be smaller than the guide width are analyzed using two models: the average-field model, which replaces the actual junction field with a uniform field and the abrupt-junction model, which accounts for the linear decrease of the electric field throughout the depletion region. The models are used to calculate the field-induced birefringence in two (Ga,Al)P heterojunction waveguide structures as a function of voltage, including the effects of the change in the depletion width, and the results are compared. Both models predict a mode dependence for the induced birefringence which is especially strong for thin modulated regions.

The finite spatial extension of the inversion layer minority carriers shunts the dielectric capacitance of the inversion layer and increases the high frequency semiconductor surface space charge layer capacitance in the strong inversion range by about 5 per cent. This distributed minority carrier distribution also gives rise to a small (about 1 per cent) high frequency capacitance minimum near the onset of strong surface inversion. A simple two-lump model is developed which is accurate to within 0·4 per cent of the numerical solution obtained from the exact transmission line model. Applied gate voltages at the capacitance minimum are presented graphically as a function of oxide thickness with the substrate impurity concentration as a parameter. Surface quantization effect is not taken into account.

Blooming, the lateral spreading of charge from an intensely illuminated area of an image sensor, can be present in an especially objectionable form in charge-coupled devices. Bright lines are formed in the display, owing to a charge propagation along the transfer channels. The introduction of overflow drains, i.e., stripes of a reverse-biased p-n junction placed between the transfer channels, provides a well-defined leakage path for excess carriers from saturated potential wells. An implanted threshold barrier between these drains and the integrating potential wells determines the saturation potential of the integration sites and prevents the total collapse of the associated depletion region. Therefore, the lateral diffusion of minority carriers is also greatly reduced. An existing design of a charge-coupled area image sensor with 64 × 106 resolution elements and frame transfer organization has been modified to study these methods of blooming suppression. The lateral distance of charge spreading has been reduced by a factor of seven at overload conditions of 20 dB. For stronger overloads the booming suppression becomes even more striking, but the performance of the device iS limited by frame transfer smearing. Furthermore, lens flare limits most optical systems at overloads above 30 dB. However, by using an optical fiber, well-localized overloads of 50 dB could be generated. Although, in our particular test device, the addition of blooming suppression reduced the light sensitivity by a factor of four, other geometries for overflow drain structures that should result in only a negligible loss in sensitivity are discussed.

Effects of high electric fields applied to the gate oxide on MOS devices have been investigated. It is found that conventional MOS devices exhibit a shift of flatband voltage in the negative direction and a decrease of channel conductance as a consequence of the higher field applied (

The effect of a low resistivity substrate on the avalanche voltage characteristics of diffused epitaxial pnn + junctions has been considered. Curves are given of the reduction in the “intrinsic” avalanche voltage and also of the movement of the depletion layer boundaries with junction voltage, thus aiding the process of optimizing the design of a transistor.

The photocurrent of a p -channel gate-controlled MOS diode, which is induced within a field-induced junction ( FI junction) and flows into drain circuits through an inversion layer, was measured. The lateral potential drop in the channel gives rise to narrowing of the depletion layer, so that the photocurrent begins to saturate for a small gate voltage or strong illumination. The spectral dependence of the photocurrent shows that the photosensitivity of the FI junction is superior to that of a PN junction in the short wavelength region because incident light can be introduced directly into the depletion layer of the FI junction. Electron excitations related to interface states are also observed in the spectral photoresponses of the samples prepared by the wet oxidation and the level is found at 0·11 eV above the valence band.

The radiation induced charge trapping at the silicon sapphire interface and its effect on MIS/SOS device performance has been experimentally determined for a total ionizing dose up to 108 rads (Si). These effects were determined by measuring the electrical characteristics of three types of device structures fabricated in SOS material: MIS devices with hardened and unhardened gate insulators, JFET's and diodes. The main emphasis is on the use of novel JFET structures for characterizing the SOS interface by modulating the gate depletion region against the sapphire substrate. Micrographs are also presented which show radiation induced changes in the staining characteristics of angle lapped and stained sections of the SOS interface. The experimental results indicate that positive charge is trapped in the sapphire substrate near the silicon-sapphire interface due to the total ionizing radiation. A model of the radiation induced charge trapping at the silicon sapphire interface is proposed.

A study of the resolution of large silicon surface-barrier detectors, operated in axial magnetic fields up to 4.0 T, has shown that a small (≈0.5%) reduction in resolution occurs which may be interpreted as arising from a slight decrease in the depth of the depletion layer.

The a-c electrical properties of bipolar membranes separating equal strength solutions of the same uni-univalent electrolyte are determined for signals of up to a few millivolts. Account is taken of the frequency dependence of the complex admittance of the depletion layer and of the Maxwell Wagner dispersion between the depletion layer and abutting regions. The analysis involves the solution ofthe diffusion equations for the mobile ions. Results are presented for the frequency dependence of the equivalent parallel combination of conductance and capacitance of the membrane for several values of the ion mobilities and for different external electrolyte concentrations.

The accuracy of the abrupt space charge edge (ASCE) approximation is studied. It is shown that the ASCE approximation is useful for exact capacitance calculations if the built-in voltage is assumed to be dependent on the space charge layer width. The classical formula C = ϵ w is not valid in this case. The new, general set of equations for capacitance calculation is derived. It can be used for an arbitrary impurity profile, and remains valid at forward bias and at any temperature. Analytical relationships for linearly graded junctions are presented. The capacitance is nearly a cube-root function of the applied voltage, as predicted by Shockley, but the value of the C−3 vs U intercept with U-axis is about 14kT 3q lower than the value obtained from the classical theory. The set of equations described in the paper can be easily solved numerically for an arbitrary impurity profile. The results of calculations for real diffused junctions are presented and compared with experiment. Some of the discrepancies between theoretical and experimental results, recently reported by Van Overstraeten and Nuyts, are explained.

Whereas the majority of methods evaluating properties of the interface between silicon and silicon dioxide requires (quasi-) equilibrium conditions of the sample, pulse and linear ramp techniques consider nonequilibrium behavior. A theoretical model of nonequilibrium behavior within the semiconductor deep depletion layer, and its consequences for the formation of an inversion region is presented providing current-voltage plots for comparison with the experimental results and discussion of various parameters (temperature and ramp velocity). The influence of donor- or acceptor-type interface states is also considered under the aspect of different temperatures. Thus some decision concerning the type is provided leading to the outlines of exact treatment, if states of either type are present.

It was found that the activation energy for hole injection at Ce4+/anthracene interface depends on the applied voltage. From an analysis of the voltage dependence the thickness of the space charge layer and the charge concentration in it could be estimated.

The modifying effects of the avalanche breakdown on the space charge density of the depletion layer of GaP/Zn,O/p-n junctions have been studied by the double square pulsed method. The thermal-emission time constant of the impurity levels may be determined from measurements of the microplasma turn-on probability vs the time interval between the two pulses. By making these measurements at various temperatures, one can find the activation energy and also the thermal-capture cross-section of the impurity levels. The analysis of the breakdown-voltage variation with time and temperature permits one to draw conclusions about the type of the individual levels (minority or majority-carrier trap) and also about the impurity impact ionization. Five impurity centers were identified in the temperature interval 77–140°K; among them two centers which might be responsible for the anomalous short minority carrier lifetime, i.e., the low quantum efficiency of the red GaP lamps.

A field effect has been measured in a semiconducting chalcogenide glass, of composition Te2AsSi. The sample was in the form of a fine filament, encapsulated within a rod of insulating glass, with the bias field applied radially. The effect is small, and the change in conductivity increases more slowly with field at high fields than at low fields. The results are explained in terms of a model with a uniform density of bulk states near the Fermi energy and a sharp surface level just below the Fermi energy. There is a depletion layer at the surface at zero bias, hence the surface barrier with no external field varied with each sample.

A comprehensive investigation has been carried out into the factors which influence the maximum drain voltage of an M.O.S. transistor for normal pentode-like operation. The drain voltage is limited by two principal mechanisms, namely punch-through of the drain depletion region to the source, and breakdown, due to impact ionization in the high field region at the drain edge. A two-dimensional analysis technique for determining the drain voltage at the onset of either punch-through or avalanche breakdown, from a solution of Poisson's equation within the substrate depletion region, is described. The solutions are obtained using finite difference numerical methods which take into account the gate-induced potential profiles at the edge of the source and drain junctions. Boundary conditions of zero effective gate bias and channel current are imposed which simplify the solution of Poisson's equation to an electrostatic one. The punch-through voltage VPT is defined as the drain-to-source voltage at which the longitudinal field at any point along the edge of the source region inverts in sign to permit the drift of minority carriers from source to drain. Breakdown voltage, VBD, however, is determined by the drain voltage at which the maximum field in the device reaches the critical value for avalanche multiplication. Good agreement is achieved between theoretical and practical results for both mechanisms on a wide variety of devices. It is shown that VPT decreases as the channel length and substrate doping concentration decrease and as the oxide thickness and diffusion depth increase. VBD, however, decreases as the channel length, oxide thickness and diffusion depth decrease. Punch-through and breakdown are discussed for gate bias conditions above and below threshold. The sharp fall in breakdown voltage as the gate bias rises above threshold is explained on the basis of injected charge from the channel into the drain depletion region.

The impedance characteristics of germanium avalanche diodes are analyzed in the frequency range 0.5 MHz‐4.5 GHz. The analysis is made taking into account the capture of impact‐ionized carriers via deep centers contained in a depletion layer. It is shown that the present model explains well the experimental results.