Recombination of charge carriers in the GaAs-based <Emphasis Type="Italic">p</Emphasis>-<Emphasis Type="Italic">i</Emphasis>-<Emphasis Type="Italic">n</Emphasis> diode

It is established that the radiative recombination of charge carriers plays a substantial role in the GaAs-based p-i-n diodes at high densities of the forward current. It is shown experimentally that the diodes operating in microwave integrated circuits intensely emit light in the IR range with wavelengths from 890 to 910 nm. The obtained results indicate the necessity of taking into account the features of recombination processes in the GaAs-based microwave p-i-n diodes.     

Self-Action of Intense Millimeter Waves in Waveguides with Integrated P-I-N Structures

The nonlinear interaction of high power millimeter (mm) electromagnetic waves with silicon integral p-i-n structures placed in a metal waveguide is theoretically investigated. The level of double injection of charge carriers due to detection of high intensity millimeter wave electric field in p-i-n structures is estimated. A mathematical model of the mutual influence of electromagnetic waves and injected charge carriers in the active region of p-i-n structures is formulated. A numerical solution of the nonlinear Helmholtz equation supplemented by proper boundary conditions on the active region boundary is obtained. The effect of high-power electromagnetic waves leads to an excessive injection of carriers into the active region of the semiconductor between p⁺-i, n⁺-i injection junctions and redistribution of the electric field in the structure. The reflection and transmission coefficients vary rapidly with the change in the input amplitude of the electromagnetic wave. This leads to bistability of these coefficients. The bistability is more pronounced in the low-frequency part of the mm range.     

Die räumliche verteilung der rekombination in legierten silizium-psn-gleichrichtern bei belastung in durchlassrichtung

Making use of the emitted infrared radiation, the charge carrier distribution n(x) in p-s-n diodes that were biased in forward direction was measured on cross-cuts. The sagging of this distribution depends on the lifetime and yields in conjunction with the stored charge a measure for that part i_m of the current density i which recombines in the weakly doped center region. The current density i, on the other hand, is a measure for the recombination in the entire diode. Therefore, infrared measurements in conjunction with determinations of the stored charge make it possible to determine for a given forward current density i the distribution i_m/i of the recombination between the weakly doped center region and the highly doped border regions.Since the radiation measurements are performed on small rectangular polished specimens (1 × 4 mm) that have been cut from the diode wafer, the measurements can be noticeably influenced by surface recombination. This influence is discussed in detail. As it turns out, only an upper limit can be given for the recombination distribution i_m/i. However, this is sufficient to ensure that already at current densities of 100–200 A cm^?2 the recombination takes place predominantly in the highly doped border regions. At current densities of 1000–3000 A cm^?2 the contribution of the center region to the recombination practically vanishes.     

Solution of the problem of charge-carrier injection into an insulating layer under self-consistent boundary conditions at contacts

The problem of charge carrier injection into a finite-length insulating layer is analytically solved in the drift-diffusion approximation, taking into account self-consistent boundary conditions. The main assumption is the neglect of intrinsic doping of the i-type layer. The solution allows calculation of the potential, electric field, and current-voltage characteristics of various structures, i.e., metal-i-n ⁺ (or p ⁺)-semiconductor, metal-i-layer-metal, and n ⁺(p ⁺)-i-n ⁺(p ⁺) structures. The solution allows generalization for structures having heterobarriers at semiconductor layer interfaces. The proposed approach considers contact phenomena and volume effects associated with the space-charge-limited current in the i-type layer. The solution is valid in both extreme cases and intermediate conditions.     

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.     

The effect of dislocations formed during growth on the structure and photoluminescence of i-n −-n-n +-GaAs epilayers and on the related microwave transistors parameters

The structure of two types of GaAs i-n ^?-n-n ⁺ epilayers on GaAs〈100〉 semi-insulating substrates was studied by electron microscopy. The low-temperature photoluminescence spectra were measured and their special features were analyzed. It is shown that the formation of dislocations during growth in such structures significantly affects the photoluminescence spectra and impairs the parameters of microwave field-effect transistors based on these structures.     

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.     

Waveguide photonic crystals with characteristics controlled with <Emphasis Type="Italic">p</Emphasis>-<Emphasis Type="Italic">i</Emphasis>-<Emphasis Type="Italic">n</Emphasis> diodes

A one-dimensional waveguide photonic structure—specifically, a photonic crystal with a controllable frequency characteristic—is designed. The central frequency of the spectral window of the photonic crystal can be tuned by choosing the parameters of disturbance of periodicity in the photonic crystal, whereas the transmission coefficient at a particular frequency can be controlled by varying the voltage at a p-i-n diode. It is shown that the possibility exists of using the waveguide photonic crystal to design a microwave device operating in the 3-cm-wavelength region, with a transmission band of 70 MHz at a level 3 dB and the transmission coefficient controllable in the range from −1.5 to −25 dB under variations in the forward voltage bias at the p-i-n diode from zero to 700 mV.     

Temperature rise in microwave p-i-n diodes: A computer aided analysis

Results of a computer aided thermal analysis of microwave p-i-n diodes are presented in this paper. The nonlinear heat flow equations in one dimension are solved using the central finite difference method of Leibman's formulation taking into account the temperature dependence of thermal conductivity and specific heat. Results are presented showing the temperature profile inside the device as a function of microwave pulsewidth and power dissipation. The effect of a heat sink on the temperature rise is also shown. The main conclusion arrived at is that the nonlinear thermal properties lead to higher temperature rise in the device and larger thermal time constants than could be expected otherwise. The method used for calculation is applicable for other solid state devices like the TRAPATT, the fast recovery thyristor, and power transistors where similar orders of power levels are involved.     

Waveguides containing frame elements with electrically controlled characteristics of permitted and forbidden bands

The feasibility of waveguide structures that have both forbidden and permitted transmission bands and are based on a diaphragm and frame coupling elements placed on both of its sides is shown experimentally and numerically using the finite element method. It is found out that the dynamic range of controlling the transmission coefficient by means of an n-i-p-i-n-structure placed in the gap between the post and the frame elements attains 23.5 dB, the transmission loss level not exceeding 1.5 dB.     

Influence of carriers on the capacitance of p-n junctions with deep donors

Applying the definition of p-n junction capacitance [1], which takes into account the effect of carriers in the space-charge region, a sufficiently accurate approximate expression is derived for the low-frequency capacitance of an abrupt p-n junction containing both deep and shallow donor impurities within the n-region. The capacitance expression can be written in conventional Schottky form, putting the intercept voltage if V_in instead of the diffusion potential. It is shown that V_in differs considerably from the generally known V_i0 expression obtained on the basis of the depletion layer approximation. This difference increases with the degree of p-n junction asymmetry, or the decrease of deep donor impurity ionisation energy, and is dependent also on the concentration ratio of deep and shallow donors. The most important difference between V_in and V_i0 lies in the fact that V_i0 in contrast to V_in, is independent of the applied voltage, and is therefore applicable only with very high reverse voltages, where equivalence between V_in and V_i0 is valid.     

Potential and limitations of Schottky-barrier barritt devices

Computer simulation of various Schottky-barrier structures is carried out to investigate the large-signal properties of these devices. Comparison between Schottky-barrier devices and their p-n junction counterparts are also made to evaluate the potential and limitations of these devices and to explain the difference in performance between them. It is shown that among various Schottky-barrier structures, the M-n-i-p⁺ structure is the most powerful one and the M-n-p-p⁺ device is the most efficient one. Furthermore, Schottky-barrier devices with low barrier heights for minority carriers (less than 0.2 eV) are capable of producing power levels close to the generated power of p-n junction devices. Investigation of the temperature dependence of the large-signal performance of these devices shows that Schottky barriers are more sensitive and exhibit their optimum performance close to room temperature value. At low temperature, the output power is limited by the low minority carrier injection, whereas at high temperature the limitation is due to the velocity-modulation losses in the injection and low-field regions of the device.     

Generation of powerful microwave voltage oscillations in a diffused silicon diode

The mechanism of the generation of powerful microwave voltage oscillations in a diffused silicon diode is studied. A reverse current 2 kA in amplitude is passed through a 0.5-cm² diode with a structure thickness of 320 μm, a p-n junction depth of 220 μm. At an average diode voltage of ～300 V and a microwave pulse duration of ～200 ns, the maximum voltage swing reaches 480 V. The oscillation frequency lies in the range 5 to 7 GHz; the power of the microwave pulse component is ～300 kW. A theoretical consideration shows that voltage oscillations are caused by periodically repeating processes of breakdown and structure filling with plasma followed by its removal by the reverse current. The frequency and voltage swing are controlled by the current density and dopant-concentration gradient in the vicinity of the p-n junction.     

Generation of microwave oscillations in a no-base diode

The GHz-frequency microwave oscillations of voltage in a no-base p ⁺-p-n ⁺ silicon diode driven by reverse current with a pulse duration of ～300 ns and a current density of several kA/cm² were experimentally observed for the first time. The mechanism of initiation of these oscillations was theoretically considered. The frequency and the modulation percentage of the microwave oscillations were shown to depend on the current density and dopant-concentration gradient in the p-n-junction plane.     

Ion-implanted bipolar transistor carrier concentration profiles

The investigation of ion implantation as a dopant process for the fabrication of narrow base width (1000 Å) n-p-n microwave (5–10 GHz) bipolar transistors has been made. The performance of a bipolar transistor is intimately related to the impurity dopant distribution in the emitter and base regions of the device. Ionized impurity profiles have been determined by making Hall effect and resistivity measurements as a function of dopant layer thickness. The profiles of arsenic, phosphorus, and boron were investigated in this matter. The phosphorus layers were formed both by diffusion and implantation, while only ion implanted boron and arsenic layers were measured. The results obtained are presented.     

A structure-oriented model for determining the substrate spreading resistance in bulk CMOS latch-up paths and its application in holding current prediction

A structure-oriented model has been developed to simulate the actual distribution of majority-carrier current flow paths in the substrate when the parasitic p-n-p-n structure with long-stripe geometry in a CMOS (complementary metal—oxide-semiconductor) circuit is at the latch-up state. Based on this structure-oriented model, the voltage drop across the latch-up path in the substrate can be calculated directly from the structure data. Therefore, the equivalent emitter-base shunting resistance in the substrate can be easily obtained and used to accurately predict the holding current. The two-dimensional numerical simulations have been carried out, based on this structure-oriented model, to obtain the emitter-base shunting resistance associated with the parasitic lateral bipolar transistor in the substrate. The computed substrate shunting resistance and the well emitter-base shunting resistance have been used to calculate the holding current with the help of the measured peak parasitic transistor gains. The predicted holding currents have been found to be in good agreement with the experimental data measured from several p-n-p-n structures, including normal and reversed layouts which are all designed by using the long-stripe geometries. Furthermore, the numerical simulations have been extended to predict the effects of the layout changes of the p-n-p-n structures on the latch-up susceptibility.     

Cathodoluminescence of p-n-p microstructures in CuInSe2 crystals

Microstructures in p-CuInSe₂ single crystals tailored by the strong electric field have been studied using the method of local (d⩽1 μm) cathodoluminescence (CL). The shortest-wavelength radiation (ℏω=1.023 eV) has been observed from the n-type layer and longer-wavelength radiation (ℏω=1.006 eV)—from the p-type regions. An analysis of the cathodoluminescence spectra has allowed us to attribute the experimental features to optical transitions associated with donor and acceptor levels of V _Cu, V _Se, and Cu_i point defects in the crystal. Test measurements of EBIC, the C–V characteristics, and the DLT spectra confirm the cathodoluminescence data and reveal additional features of the p-n-p microstructures. Fiz. Tekh. Poluprovodn. 31, 114–119 (January 1997)     

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.     

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.     

Influence of the electron-hole equilibrium shift on transition-metal diffusion in GaAs

Diffusion of impurities of transition metals Fe, Cu, and Cr in heavily doped p ⁺-, n ⁺-, and intrinsic (at diffusion temperature) GaAs is studied. A technique in which impurity diffuses into GaAs-based structures with heavily doped layers (p ⁺-n or n ⁺-n) was used. It is shown that the impurity diffusivity values in p ⁺-GaAs and n ⁺-GaAs are significantly higher and lower, respectively, than for i-GaAs. The results obtained are discussed taking into account the effect of the electron-hole equilibrium shift in semiconductors on the diffusion of impurities migrating according to the dissociative mechanism. The interstitial-component concentration for Fe, Cu, and Cr impurities in GaAs was determined at the diffusion temperature.