BARITT Diodes Research Articles

Plasma extraction transit time oscillations in bipolar power devices

Disturbing high frequency oscillations observed during turn-off of IGBT modules can be explained by (i) a local parasitic resonant circuit and (ii) a new r.f. generator mechanism similar to the BARITT diode effect. The phenomenon is related to periodic hole extraction from the electron–hole plasma. Therefore it will be called “plasma extraction transit time” effect. This effect can be modelled using device simulation. The r.f. generation efficiency is very small. Resonator Q-factor, resonance frequency and carrier transit time must fit well to enable excitation of the parasitic resonant circuit.

Microwave characteristics of BARITT diodes based on silicon carbide

Microwave characteristics of barrier-injected (BARITT) diodes made of silicon carbide are investigated. It is shown that the negative resistance of p/sup +/-n-p/sup +/ structure made of different polytypes of SiC is an order of magnitude higher in absolute value in comparison with the Si p/sup +/-n-/sup +/ structure, all other factors being equal, even in the absence of trap levels (TLs). It is shown also that the dynamic negative resistance, in absolute value, the power output and efficiency increase with an increase of the concentration of traps. The effects of TLs in the band gap of the semiconductor on the impedance, power output, and efficiency of SiC BARITT diodes are examined,.

Microwave characteristics of BARITT diodes based on silicon carbide

Microwave characteristics of BARITT diodes made of silicon carbide are investigated. It is shown that the negative resistance of a p +–n–p + structure made of different polytypes of SiC is an order of magnitude higher in absolute value in comparison with a Si p +–n–p + structure, all other factors being equal, even in the absence of trap levels. Furthermore it is shown that the dynamic negative resistance, the power output and efficiency increase with an increase of the density of traps. The effects of trap levels in the band gap of the semiconductor on the impedance, power output and efficiency of SiC BARITT diodes are examined.

Radiation effects in ultraviolet sensors based on natural diamond

Total dose and dose rate effects are investigated in ultraviolet sensors based on natural diamond with various concentrations of nitrogen impurity. Transient effects in the devices based on IIa-group natural diamond are described with a BARITT diode model.

Silicon Ka band low noise BARITT diodes for radar system applications grown by MBE

Silicon K a band BARITT ( Bar rier I njection T ransit T ime) diodes in the frequency regime from 26 to 31 GHz have been grown by MBE with a p- n- p doping sequence. CW powers of 4 mW at 29 GHz have been realized from fabricated mesa diodes with diameters of ⊘ = 55 to 65 μm, the diodes exhibited a signal to noise ratio of S/( NΔf) = 93 dBc/Hz ( Δf = 100 kHz).

Conversion matrix and gain of self-oscillating mixers

The conversion matrix of self-oscillating mixers is derived from the bias-, amplitude-, and frequency-dependent admittance of the active device together with its dynamic current-voltage characteristic. Components at the image frequency are also taken into account. With this matrix and the circuit admittances at the different frequencies involved, the conversion gain can be expressed. For better insight into the relevant mechanisms, the conversion gain is subdivided into the amplitude response of the self-excited oscillation to an input signal and the demodulation caused by the device internal rectification. The formalism is applied to a simplified model of an oscillating BARITT diode. The resulting analytical expressions allow a discussion of the influence of different device and circuit parameters as well as a qualitative and quantitative comparison with experimental results from a self-oscillating BARITT-diode mixer operating in the V-band at 60 GHz. >

Elimination of surface current induced failure in millimetre wave Baritt diodes

The influence of surface charges on the current/voltage characteristics of Baritt diodes is described and an improved Baritt diode geometry avoiding surface currents is suggested which leads to sharp I/V behaviour and hence to stable oscillation conditions.

60 GHz BARITT diodes as self-oscillating mixers

The fabrication of Pt np+ silicon baritt diodes for V-band frequencies is described. An oscillating output power of 1 mW at 60 GHz could be attained. The diodes were investigated as self-oscillating mixers in Doppler-radar and local-oscillator applications. A conversion gain of 26 dB and a minimum detectable signal of ?160 dBm (1 Hz bandwidth) could be measured near the carrier.

BARITT diodes for millimetre-wave frequencies

The design and fabrication of Schottky BARITT diodes is described for a frequency range 35–50GHz. At 40 GHz a maximum output power of more than 3 mW could be realized.

The BARITT diode — A low noise heterodyne photodetector with high integral gain

Optical detection properties of wellknown microwave BARITT diodes are described. As a result of bulk barrier modulation due to accumulation of photogenerated charge carriers the devices exhibit high internal gain when used as a direct photodetector. Moreover, transit time effects give rise to another kind of internal gain at certain microwave frequencies which can be advantageous in optical heterodyne techniques. Basic experimental results of photodetector sensitivity are discussed.

Numerical simulation of microstrip Baritt oscillators

A complete numerical simulation of a Baritt diode microstrip oscillator is described, and the important effects of diode and circuit temperature are discussed. Results of the numerical simulation are compared with thermal and electrical measurements on oscillator circuits and found to be in good agreement. The circuit model was used as a basis for the design of Baritt diode Doppler modules, indicating how frequency drift with ambient temperature may be improved. A C-band Doppler module was constructed which drifts less than 10 MHz between −20°C and +40°C.

Self-detecting microwave spectrometer based on the BARITT diode

An improved microwave oscillator using a commercial BARITT device as a self-detecting source of 12–14 GHz radiation is described. As an electron-spin-resonance spectrometer the sensitivity is on the order of ∼ 1.5×1012 standard spins. Operation is particularly easy since the BARITT readily self-rectifies at all oscillation levels.

Use of Microstrip Impedance- Measurement Technique in the Design of a BARITT Diplex Doppler Sensor

A computer-aided microstrip impedance-measurement technique, which yields information on microstrip-material properties, is described. The technique is used to investigate the impedence of microstrip-mounted BARITT diodes and of microstrip pad antennas. A Doppler sensor is designed, incorporating the BARITT diode into a microstrip circuit, used in diplex Doppler range-measuring radar.

Baritt diodes for ka-band frequencies

Design rules for uniformly doped Baritt diodes in the frequency range 8 to 40 GHz are derived. The fabrication of Ka-band Baritt diodes which deliver up to 1.7 mW is described. The theoretical and experimental results of the investigated diodes fit very well.

Ka-band self-oscillating mixers with Schottky BARITT diodes

The fabrication of Pt n-p+ silicon Baritt diodes is described which can deliver more than 4 mW at Ka-band frequencies. The diodes were investigated as self-oscillating mixers. A minimum detectable signal of -154 dBm as well as a conversion gain of 26 dB could be realised.

The internal dynamics and small signal analysis of BARITT diodes

A “two-carrier” computer simulation showing the transient response of BARITT diodes to an applied current step is presented. The internal dynamics of the diode in terms of the time evolution of the electric field, electron and hole densities as well as both conduction and displacement currents are discussed. The dynamics of the solution reveals the formation of a low field region at the injecting contact, a result which is not obtainable from “one-carrier” models of BARITT diodes. A small signal analysis is performed on the steady state solution and demonstrates an increased differential negative resistance (DNR) for increased device length at a given doping, and an increased DNR coupled with a wider frequency bandwidth for a decrease in carrier lifetime at the injecting junction.

Design and development of high-power microwave silicon BARITT diodes

A method of design and fabrication for high-power high-frequency silicon BARITT diodes is described. Pt-Schottky BARITT structure developed in this study yielded the largest pf2product reported so far. Very good agreement between the theoretically calculated and expeximentally measured values of the reachthrough voltages and the optimum frequency of operation were observed. This proves the validity of the basic assumption used in the design calculations.

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.

The noise characteristics of baritt diodes with traps

The noise characteristics of a semiconductor punchthrough structure are examined for operation under low-field conditions, i.e. constant mobility, and for trap levels in the bandgap of the semiconductor. It is shown that the noise measure is decreased under the influence of trapping of injected carriers, for the small-signal injection approximation. With the increase of the concentration of traps, the noise measure decreases, but the frequency band, where it takes place, narrows and is displaced to a lower frequency.

Effect of temperature on Baritt diode large signal performance

Effect of temperature on Baritt diode large signal performance