InP Transferred Electron Devices Research Articles

InP series-like transferred electron device for CW submillimeter-wave power sources

The potential of vertical series-like InP transferred electron devices operating in the electron accumulation layer and multiple transit-time mode is investigated at 400 GHz by means of one-dimensional time-domain energy/momentum numerical modeling. The device structure has been optimized at 500 K. The RF operating mode is analyzed. The potential of two- and three-transit series-like TED is compared to the performance of a classical single-transit N+NN+ TED. The series-like TED clearly improves the RF performance and impedance level and consequently is a possible solution to extend the TED frequency limitation at submillimeter wave. The device RF operation stability and thermal consistency of the results are analyzed.

Preparation of 100 GHz InP Transferred Electron Devices

This paper reports on the development of InP transferred-electron-device sources in mainland of China for operation at around 100 GHz. Using n+-n-n+ structure with graded doping profiles, the oscillations were obtained at 101.8 GHz from a 1 μm structure with an n-doped drift zone and the doping concentration linearly increases from 1.0×1016 to 3.0×1016cm-3. Its continuous wave radio frequency (CWRF) output power was evaluated to be several milliwatt and these results are believed to correspond to a fundamental mode operation. This result is attributed to a processing technique based on the use of etch-stop layers, removal of substrate and the formation of good ohmic contacts.

Comparison of modulated impurity-concentration InP transferred electron devices for power generation at frequencies above 130 GHz

In this paper, InP transferred electron devices of various doping profiles have been theoretically investigated for fundamental- and harmonic-mode operation at frequencies up to 260 GHz. The results are based on an efficient and accurate hydrodynamic simulator, which analyzes the device under both conditions: impressed terminal voltage and realistic load impedances. In comparison with state-of-the-art graded profile diodes, improved performance is demonstrated for modulated impurity-concentration devices for both modes of operation.

A 63-170 GHz second-harmonic operation of an InP transferred electron device

Theoretical and experimental analysis of a second-harmonic InP transferred electron device is presented for the 63-170 GHz frequency band. This broadband device produces 30 mW at 63 GHz, 85 mW at 122 GHz, and 8 mW at 170 GHz; in all cases the diode is operating in the second-harmonic mode. A continuously-tunable cavity has been used to produce 30-40 mW of output power over the 119-147.5 GHz range without any detectable frequency jumps or power dips. High frequency structure simulator (HFSS) and drift-diffusion harmonic-balance analysis (DDHB) are used to self-consistently analyze the second-harmonic TEO operation. Numerical simulation results are presented that explain the broadband behavior of the device, and determine the optimal device embedding impedance. Simulations are capable of predicting operating frequencies to within several GHz and output powers to within about 20% accuracy.

Monte Carlo-based harmonic-balance technique for the simulation of high-frequency TED oscillators

A harmonic-balance technique for the analysis of high-frequency transferred electron device (TED) oscillators is developed. The behavior of the nonlinear TED is not obtained from a quasi-static equivalent circuit; rather, a physical transport model is used to determine its response in the time domain. This model is based on the ensemble Monte Carlo technique coupled to a heat-flow equation, which accounts for thermal effects on the device operation. It is found that the standard splitting method for updating the unknown voltage across the diode fails to converge to a steady-state solution at the fundamental frequency. A modified version is proposed, which updates the voltage at the fundamental and higher harmonics differently. This method exhibits much better convergence behavior. Simulation results obtained with the complete model are in very good agreement with experimental data from InP TED oscillators operating at 131.7 and 151 GHz in the fundamental mode and at 188 GHz in the second-harmonic mode.

Efficient computer aided design of GaAs and InP millimeter wave transferred electron devices including detailed thermal analysis

An accurate calculation of the large-signal a.c. behavior with detailed thermal considerations is presented for GaAs and InP transferred electron devices. This is accomplished by sequentially solving the temperature dependent drift and diffusion equations along with a novel heat flow analysis to update the temperature profile in the device. The drift and diffusion equations employ both field and temperature dependent mobility and diffusivity derived from Monte Carlo simulations, and the thermal analysis includes all regions of the device. Simulation results are compared to experimental devices with good agreement. The relationship between the graded active layer doping profiles, device area and device length, with the device temperature, output power and device admittance is clearly illuminated by the temperature dependent large-signal a.c. simulator. For the devices simulated, the complex device admittances are calculated over the range of stable operation and at the maximum power point.

Study of submicron InP transferred electron devices

We have performed an experimental and numerical investigation of near-micron, and a numerical investigation of submicron sized InP transferred electron devices (TEDs) having alloyed metal cathode ‘‘current-limiting’’ contacts. A drift and diffusion analysis utilizing a modified Schottky barrier for the cathode contact was used to model the dc characteristics of near-micron structures, while a Boltzmann transport equation moments analysis with a cathode mobility model was implemented in order to simulate the ac and dc results in general. Our theoretical study emphasized the length effect for submicron structures. A generalized ‘‘different areas rule’’ for short devices was compared with the results of our numerical analysis. Submicron InP TEDs were studied and simulated numerically in the near millimeter wave region (100–250 GHz). The static velocity-field, v(E), characteristics showed a large deviation from long device behavior (≳1.0 μm) as the device length decreased into the submicron region. The upper limit for the transit-time frequency was predicted numerically to be about 230 GHz for a 0.2-μm InP TED. The interrelated controlling parameters: device length, bias, boundary conditions, doping density, were investigated in the numerical analysis and utilized to set design rules.

High efficiency and output power from second- and third-harmonic millimeter-wave InP-TED oscillators at frequencies above 170 GHz

InP TED (transferred electron device) oscillators have been experimentally investigated for frequencies between 170 and 279 GHz. It has been found that output powers of more than 7 and 0.2 mW are possible at 180 and 272 GHz using second- and third-harmonic mode operation, respectively. Conversion efficiencies of more than 13% and 0.3% between fundamental and second harmonic and fundamental and third harmonic, respectively, have been found. The conversion efficiencies are comparable to GaAs TEDs. The output powers, conversion efficiencies, and tuning ranges (more than 22%) are the biggest reported for InP TEDs at these frequencies. The output power at third harmonic was sufficient for supplying a superconducting mixer with local oscillator power.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">&gt;</ETX>

A numerical analysis of submicrometer InP-transferred electron devices

A numerical technique combining the Boltzmann transport equation and a cathode mobility model has been used to simulate the nonuniform field configurations and the static and dynamic transport behavior of submicrometer InP-transferred electron devices (TEDs). Significant interrelated controlling features for the 70-230-GHz operation of these devices have been analyzed. They determine the manifestation of the current instabilities in the following ways: (1) the length has a significant effect on the velocity-field characteristics for submicrometer TEDs, and thus on the oscillation threshold as well as the upper-frequency limit for transit-time oscillations; and (2) the cathode mobility (boundary condition), doping density, and bias acting together have a dominant effect on the threshold and cutoff of the current instability. The numerical results can be used to determine the optimum efficiency and frequency of actual devices. >

Millimeter-wave InP lateral transferred-electron oscillators

A lateral InP transferred-electron device (TED) designed with a high-resistivity notch adjacent to the cathode contact is presented, and its application to millimeter-wave monolithic integrated circuits is demonstrated. At 29.9 GHz, a CW power output of 29.1 mW with a conversion efficiency of 6.7% has been obtained from cavity-tuned discrete devices. This result represents the highest power output and efficiency of a lateral TED in this frequency range. The lateral devices also had a CW power output of 0.4 mW at 98.5 GHz and 0.9 mW at 75.2 GHz. A 79.9-GHz monolithic oscillator incorporating the lateral TED is reported. Experimental and theoretical results which further the understanding of the lateral device operation are presented.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">&gt;</ETX>

The influence of cathode contacts on near-micron InP transferred electron devices

We have performed an experimental investigation of twenty-five 1.5 to 2.0 μm long InP TED's in tunable resonant structures at frequencies in the 75–100 GHz regime, and have simulated their behavior, and that of shorter devices, numerically. We have found that the cathode boundary condition determines the operation of near-micron InP TED's in the following ways: it controls the threshold conditions; it controls the required dc bias power; it affects the transit-time frequency of the device; it influences the electric field profile for an appreciable distance from the cathode.

A study of near-micron InP transferred electron devices

Abstract We have experimentally investigated a large number of InP Transferred Electron Devices ranging from 1 to 2 microns in thickness, and have numerically simulated their behavior using both a drift and diffusion model and a Boltzmann transport equation approach. We were able to fit the static I(V) curves and threshold conditions rather well by a proper choice of ideality factor, n, in the control characteristic, which we assumed to be that of a Schottky diode.

Noise in millimetre-wave oscillators

A brief outline is given of oscillator noise theory in order to introduce the concept of a noise measure as a means of defining a figure of merit for oscillator devices. Details are then given of a.m. and f.m. noise measurement techniques as applied to devices operating at millimetre wave frequencies. Using these techniques a comparison is made of the relative noise performance of both GaAs and InP transferred electron devices (t.e.d.s) and Si double-drift Impatt devices. It is thus shown that GaAs and InP t.e.d.s exhibit very similar noise performances with InP having the advantage of a higher power and efficiency capability. More surprisingly the results also prove that the Si double-drift impatt can exhibit low-noise behaviour under certain bias conditions. Finally it is concluded that the choice of oscillator devices for millimetre wave uses is more complex than previously thought and the double-drift impatt is now a real contender for low-noise systems use.

Fully integrated W-band microstrip oscillator

A fully integrated microstrip oscillator is described. The active element is an InP transferred-electron device operating in its fundamental mode of oscillation. For measurement purposes, the oscillator structure is mounted in a test assembly and fitted with a waveguide to microstrip transition. Output powers of 16 mW have been observed at the waveguide output port at frequencies in the range 80 GHz to 83 GHz. Transition and circuit losses are approximately 3 dB indicating a device output power of 32 mW.

High efficiency InP transferred electron device for high peak power, high mean power pulsed sources in J -band

High efficiency indium transferred electron pulsed diodes have been shown to produce high peak powers simultaneously with moderately high mean power with DC to RF conversion efficiencies up to 22% at upper J-band frequencies. Devices have been combined in four-diode waveguide array circuits to produce powers of 40 W peak, 2 W mean simultaneously, and 64.5 W at lower duty cycle.

High-efficiency and high-peak-power InP transferred-electron oscillators

It has been demonstrated that a current-limiting cathode contact can be used to improve the performance of relatively thick vapour eptaxial InP transferred-electron devices. A peak power of 120 W with 18% efficiency at 5 GHz has been obtained from 34 μm-thick active-layer devices with silver tin-alloy metal contacts.

Transit modes of InP transferred-electron devices

The characteristics of accumulation transit oscillations in InP n+-n-n+ transferred-electron oscillators and the dependence of device efficiency on the injection properties of the cathode contact have been analysed by computer simulation.

Low-noise microwave amplification using transferred-electron and baritt devices

The small signal amplifying properties of both GaAs and InP transferred electron devices and of Si baritt devices are considered using simple physical models. InP is predicted theoretically to be capable of providing devices having the lowest noise measure. The paper shows that, for transferred-electron amplifiers, an optimum value of nl product exists for lowest noise measure.

Overlength modes of InP transferred-electron devices

Simulations of overlength modes in InP transferred-electron devices indicate microwave conversion efficiencies greater than 25%. The maximum frequency of operation exceeds 20 GHz. but depends markedly on the nature of the electronic intervalley scattering processes and associated relaxation effects.

The effects of temperature on epitaxial InP transferred electron devices

The performance of Indium Phosphide microwave oscillators is examined over the temperature range 110-470 K. The threshold field of the devices is shown to vary from 7 kV.cm-1at 110 K up to 10 kV. cm-1at 470 K, with a value of 8 kV.cm-1at room temperature. The results indicate little falloff in the operating efficiency of the oscillators between room temperature and 470 K. The operating frequency bands are shown to fall with increasing temperature with the frequency for maximum power changing by about 18 percent over the range 290-470 K.