Heat flow resistance measurements of silicon p+-v-n+ diodes under forward and reverse biased conditions

A detailed study of the heat flow resistance measurements in a p⁺-v-n⁺ diode is studied in both forward and reverse biased conditions. Measurements are made by continuously switching the diode from the power dissipation state into the temperature measuring state. Safe operating power limits are identified for the diodes depending upon their mode of operation either as a microwave switch or as an IMPATT oscillator.     

Drift of the breakdown voltage in p-n junctions in silicon (walk-out)

A quantitative model for the time behaviour of the walk-out phenomenon in planar p-n junctions is given. The injection of hot carriers into SiO₂ and subsequent trapping of part of them is assumed to be the origin of the walk-out. The model is found to be in reasonable agreement with the experimental results on both p⁺?n and n⁺?p junctions. The parameters in the model are discussed in relation with the experiments.     

Shot noise in back biased p-n silicon diodes

An earlier calculation of the noise due to generation of carriers in the space charge region in a p-n silicon diode by Lauritzen and by Scott and Strutt is corrected for the fact that the field distribution in the space charge region of a p-n junction is linear instead of uniform. If the noise is expressed as S_I(f) = 2eIΓ², we find $\text{Γ}{}^2\text{=}\text{11}\text{15}$ in a p⁺n or n⁺p junction, instead of $\text{Γ}{}^2\text{=}\text{10}\text{15}$ found previously.     

Silicon p−n insulator-metal (p-n-I-M) devices

Silicon p-n-I-M devices with thin insulating layers ($\text{thicknesses}\text{? 30}\text{A}\text{?}$), named MTIS devices, have been developed. The two terminal device shows an S-shaped negative resistance characteristics similar to a Schockley diode (or p-n-p-n diode). Typically the threshold and sustaining voltages are 10 ～ 15 and 1.3 ～ 2 volts, respectively. The former however can be controlled by optical illumination. Turn-on time including delay is less than 2 nsec and turn-off time ? 1 nsec or less. A thyristor-like device with its third terminal connected to the n-layer shows switching operation controllable by this terminal. A monolithic linear array of p-n-I-M diodes with 30 μm spacing operates as a shift register through coupling of adjacent diodes. Life of the two terminal devices recorded at present is over 1.5 × 10⁴ hr. These devices can be applied to low power and high-speed electrical switching and also to optical switching and integrated logic circuits.     

Theory of open circuit voltage decay in a p-n junction diode at high injection

A high injection theory of open circuit voltage decay in a p-n junction diode is given. The theory takes into account the saturation of junction voltage at high injections and coupling between emitter and base of the diode. The results are in qualitative agreement with the available experimental results. In particular the theory explains the plateau which has been observed in most experimental results on the open circuit voltage decay at high injections.     

A computer-aided simulation model for the I–V characteristic of M-n-p silicon Schottky-barrier diodes produced by use of low-energy arsenic-ion implantation

Current-transport properties of Al-n-p silicon Schottky-barrier diodes have been studied both experimentally and theoretically. An analytical model for the I-V characteristic of a metal-n-p Schottky barrier diode has been developed by using an interfacial layer-thermionic-diffusion model. Assuming a Gaussian distribution for the implanted profile, the barrier-height enhancement and ideality factor have been derived analytically. Using low energy (25 KeV) arsenic implantation with the dose ranged form 8 × 10¹⁰/cm² to 10¹²/cm², Al-n-p silicon Schottky barrier diodes have been fabricated and characterized. Comparisons between the experimental measurements and the results of computer simulations have been performed and satisfactory agreements between these comparisons have been obtained. The reverse I–V characteristics of the fabricated Al-n-p silicon Schottky barrier diodes can also be well simulated by the developed model.     

On the small-signal equivalent circuit of p-n junctions in the condition of finite carriers multiplication

A new version of the equivalent circuit of the space-charge region of the reverse biased p-n junction is evaluated and the expressions for the circuit parameters are given. The basic idea is to separate the equivalent circuit in to the “conductive” and “displacement” branches and in this way the equivalent circuit parameters have physical meaning. The results are applicable to conditions of the finite multiplication factors and unequal ionization coefficients in a wide range of frequency and in the presence of the generation of carriers (thermal or outside induced) in the space-charge region. The numerical results for two complementary abrupt silicon p-n junctions and for low-frequency are given. The equivalent circuit of the multiplication noise source of the p-n junction is discussed.     

p+-n--n+-type power diode with crystalline/nanocrystalline Si mosaic electrodes

Using p⁺-type crystalline Si with n⁺-type nanocrystalline Si (nc-Si) and n⁺-type crystalline Si with p⁺-type nc-Si mosaic structures as electrodes, a type of power diode was prepared with epitaxial technique and plasma-enhanced chemical vapor deposition (PECVD) method. Firstly, the basic p⁺-n^--n⁺-type Si diode was fabricated by epitaxially growing p⁺- and n⁺-type layers on two sides of a lightly doped n^--type Si wafer respectively. Secondly, heavily phosphorus-doped Si film was deposited with PECVD on the lithography mask etched p⁺-type Si side of the basic device to form a component with mosaic anode. Thirdly, heavily boron-doped Si film was deposited on the etched n⁺-type Si side of the second device to form a diode with mosaic anode and mosaic cathode. The images of high resolution transmission electronic microscope and patterns of X-ray diffraction reveal nanocrystallization in the phosphorus- and boron-deposited films. Electrical measurements such as capacitance-voltage relation, current-voltage feature and reverse recovery waveform were carried out to clarify the performance of prepared devices. The important roles of (n^-)Si/(p⁺)nc-Si and (n^-)Si/(n⁺)nc-Si junctions in the static and dynamic conduction processes in operating diodes were investigated. The performance of mosaic devices was compared to that of a basic one.     

A simplified theory of the p-i-n diode

A simplified theory of the p-i-n diode is developed for the case of heavy injection in the base, and light injection in the end regions. The current I is taken as the fundamental parameter. The carrier densities n₁ and n₂ at the base boundaries are given directly as functions of the current I by means of simple approximate expressions. The approximation improves with increasing base width and increasing current. It is always within 15% of the correct value for base widths of about 2 diffusion lengths or higher. The accuracy is much better still on the voltage drop across the device, as calculated from the approximate equations for the carrier densities within the base.     

An extension of the ideal diode analysis for the heavily doped p-n diode

In this paper, an extension of the ideal-diode analysis for the heavily-doped p-n junction diode is proposed. The heavy doping effects such as carrier degeneracy and band gap narrowing are accounted for by using a tractable empirical approximation for the reduced Fermi-energy given by[12] and employing effective intrinsic density. Under the assumption of low-level injection, it is found that the injected minority-carrier current, and the charge storage in the quasi-neutral regions should depend exponentially on values of F(Y), where F(Y) is a function of dopant dentisy at the depletion edge of the quasi-neutral emitter (or) base region of the p-n junction. Results of our calculations of excess hole current for the short base and the long-base diode show significant change from the values predictged by the conventional diode theory.     

Crystal damage and the properties of implanted p-n junctions in silicon

The influence of crystal damage on the properties of implanted p-n junctions has been studied by variation of the amount of initial damage, variation of the recovery process, and variation of the residual damage. This was done by carrying out implantations at - 196, 25 and 700°C with 10¹⁵ B⁺/cm² at an energy of 50 keV, and at 25°C with 10¹⁵ BF₂⁺ at an energy of 250 keV and 10¹⁵ Ga⁺/cm² at an energy of 70 keV. Substrate orientations of both 〈111〉 and 〈100〉 were used, and annealing was done in a temperature range between 400 and 1100°C. Gettered as well as non-gettered slices were used for 〈111〉 oriented substrates. The diode properties were analyzed with the aid of Shockley-Read-Hall recombination statistics. Depending upon crystal history and processing, different traps are found to dominate the reverse current. Traps caused by the gettering of contamination as well as those caused by the damage itself play a role. The number of traps is found to be smaller than 10¹²/cm³ for well annealed diodes, resulting in a reverse current density of 0.2 nA/cm² at 1 V reverse bias.     

Impact ionization wave breakdown of drift step recovery diodes

High frequency IMPATT oscillations followed under certain conditions by reversible impact ionization wave breakdown of the p ⁺-n-n ⁺ diode structure have been experimentally observed for the first time in a drift step recovery diode operating in the avalanche breakdown mode after a fast voltage restoration of the p-n junction.     

Harmonic distortion in a one-dimensional p-n-p transistor

A method to obtain nonlinear distortion of small a.c. signals in a one-dimensional bipolar transistor is described. The fundamental physical semiconductor equations are the basis from which the small-signal relations are derived. A finite difference scheme is employed to achieve space-discretization; temporal dependence of input-output relations is given in terms of Volterra functional series. The internal distribution of quasi-Fermilevels, potential and excess carrier densities is discussed and some computational results are produced. The influence of frequency, bias point, and external circuit elements on distortion properties is illustrated. Throughout, a common-emitter p-n-p transistor structure is assumed. The theory of Volterra series analysis is briefly summarized.     

High-voltage planar junction with a field-limiting ring

A twodimensional Poisson equation is solved as part of a program to improve breakdown characteristics of a planar p-n junction by using a field limiting ring. The influences of n^? concentration and n^? layer width of p⁺-n^?-n⁺ diode are investigated. Higher n^? concentration and smaller n^? width make optimum distance between anode and field limiting ring smaller. Breakdown voltages predicted by optimising method reported agree well with the experimental results.     

C–V index of hyperabrupt p-n junctions

C–V index n for hyperabrupt p⁺-n junctions with exponentially retrograded n-region has been computed numerically for different values of parameters characterizing the impurity profile and the results have been plotted graphically. Although n is found to vary with the bias across the junction for any given impurity distribution, the maximum value nmax of n is determined only by the ratio of the background concentration to the crossover concentration in the retrograded region. By making this ratio R₀ smaller and smaller, values of n substantially larger than unity can be obtained. Practical considerations, however, limit the maximum value of n to about 10. An empirical relation expressing nmax as a function of the ratio R₀ has been obtained. Calculated results are compared with the values of n measured on hyperabrupt junctions fabricated by a double diffusion process.     

Effect of reabsorbed recombination radiation on the saturation current of direct gap p-n junctions

The radiative transfer theory for semiconductors recently developed is applied to p-n junctions under conditions of low level injection. By virtue of the interaction of the radiation field with free carriers across the depletion layer or space charge region, the saturation current density j₀ in Shockley's expression j = j₀[exp (qV/kT) ? 1] for the diode current is reduced at high doping levels from the customary value which neglects radiation effects altogether. While the effect is insignificant in p-type material, it is noticeable in n-type material owing to the small magnitude of the electron effective mass in direct gap III–V compounds. At an equilibrium electron concentration of 2 × 10¹⁸ cm^?3 in GaAs, a reduction of j₀ by 15% is predicted.     

Effect of irradiation with fast neutrons on electrical characteristics of devices based on CVD 4<Emphasis Type="Italic">H</Emphasis>-SiC epitaxial layers

The effect of irradiation with 1-MeV neutrons on electrical properties of Al-based Schottky barriers and p⁺-n-n⁺ diodes doped by ion-implantation with Al was studied; the devices were formed on the basis of high-resistivity, pure 4H-SiC epitaxial layers possessing n-type conductivity and grown by vapor-transport epitaxy. The use of such structures made it possible to study the radiation defects in the epitaxial layer at temperatures as high as 700 K. Rectifying properties of the diode structures were no longer observed after irradiation of the samples with neutrons with a dose of 6×10¹⁴ cm^?2; this effect is caused by high (up to 50 GΩ) resistance of the layer damaged by neutron radiation. However, the diode characteristics of irradiated p⁺-n-n⁺ structures were partially recovered after an annealing at 650 K.     

Depletion layer formation,space-charge injection and current-voltage characteristics for the silicon p-n-p (n-p-n) structure

Depletion layer formation and current-voltage characteristics are described for the general semiconductor p-n-p (n-p-n) structure in which the impurity or defect centre is able to communicate with both sets of transport levels. All possibilities for current lie within the region bounded on one side by the essentially vertical Shockley-Prim punch-through characteristic and on the other side by the square-law Mott-Gurney space-charge-limited characteristic. If the impurity levels lie near the mid-gap position a variety of characteristics within this region can be expected. Representative current-voltage characteristics have been computed and are described for a typical silicon structure.     

Current-voltage characteristics of GaAs p-i-n and n-i-n diodes

Using the same basic equations as Kazarinov et al.[2], but assuming that the product of the electron drift velocity and of the electron lifetime remains constant, we have derived a new formula for the forward d.c. current—voltage characteristic distinguished by the saturated voltage. We have shown that this formula can describe the measured characteristics of some GaAs p-i-n and n-i-n diodes.     

1/f noise in n+-p-n microwave transistors

1/f noise measurements in the base current and the collector current of NEC 57807 n⁺-p-n microwave transistors show that the noise is not of the mobility fluctuation type, since the current dependence of S_IR(f) and S_IC(f) differs from the theoretical predictions. The low collector current 1/f noise makes it doubtful whether the mobility fluctuation concept is applicable in this case.