Physical understanding and optimum design of high-powermillimeter-wave pulsed IMPATT diodes

A physical understanding of the specific mode of operation of high-power millimeter-wave pulsed IMPATT diodes is derived from a self-consistent numerical model. It is shown theoretically that there exists a uniformly avalanching p-i-n-like mode in high-current-density, pulsed silicon double-drift IMPATT diodes, as has been previously suggested. An optimum symmetrical flat doping-profile double-drift structure for 100-GHz operation is presented. It could deliver more than 40 W of available peak power with a 10% conversion efficiency accounting for circuit losses, at a safe junction temperature rise. The theoretical results allow an optimum design of the 94-GHz IMPATT structure for peak output power in excess of 50 W under low duty cycle     

Multi-layer epitaxially grown silicon impatt diodes at millimeter-wave frequencies

Complementary (N⁺PP⁺) and double-drift (N⁺NPP⁺) silicon IMPATT diodes were prepared and investigated as oscillators in the millimeter-wave frequency region of 50 to 70 GHz. All the diodes were fabricated from multi-layer epitaxially grown silicon structures. A maximum CW output power level of 198 mW at 62.9 GHz and a maximum conversion efficiency of 7.3% have been measured for the complementary diodes. The double-drift IMPATT diodes have a maximum CW output power of 400 mW at 56.3 GHz and a maximum conversion efficiency of 8.5%.     

Effects of ionization rates on silicon IMPATT devices

The effects of ionization rates of electrons and holes on the properties of silicon IMPATT devices are presented. Both p-type and n-type silicon diodes are considered. Small- and large-signal results are given for typical X-band devices.     

Simplified particle simulation of millimeter-wave IMPATT devices

A simplified microscopic model for investigating energy relaxation effects in millimeter-wave IMPATT devices is presented. A statistical process is used to describe electron-hole multiplication by impact ionization from knowledge of the ionization coefficients. These coefficients are assumed to be functions of the individual energy of carriers (holes and electrons). A relaxation time formulation is used to calculate the energy of each carrier. Drift in the electric field and diffusion are modeled using the diffusive model proposed by Hockney. Simulations are carried out for silicon diodes. It is found that inclusion of the energy relaxation mechanisms modifies mainly the avalanche process for such material. The implications of these mechanisms on device performances are then discussed by calculating the large signal level dependence of the conversion efficiency and admittance for a typical double-drift structure at 100 GHz. The resulting calculations show good agreement with existing experimental data on these structures.     

Pulsed silicon double-drift IMPATTs for microwave and millimetre-wave applications

The letter describes silicon double-drift IMPATT diodes designed for operation at microwave and millimetre-wave frequencies. These devices have delivered pulsed-power outputs of 16 W with 12.3% efficiency in the X band, 11 W with 14% efficiency in the KU band, and 6.4 W with 5.3% efficiency in the Ka band. These results, when combined with the demonstrated high reliability of silicon IMPATTS, should lead to the wide application of double-drift devices in pulsed-radar systems.     

Double-drift millimetre-wave IMPATT diodes prepared by epitaxial growth

The preparation of silicon double-drift millimetre-wave IMPATT diodes by the epitaxial growth of n- and p-type layers successively on n-type substrates is described. Carrier-concentration profiles comparable with those reported for double layers formed by ion implantation are obtained; a microwave output power of 560 mW with 11% efficiency has been achieved at 48 GHz.     

Design considerations of high-efficiency double-drift silicon IMPATT diodes

High-efficiency silicon double-drift IMPATT diodes with a low-high-low doping profile structure are proposed. Devices with efficiencies of 25 percent for 12 GHz, 24 percent for 18 GHz, and 19 percent for 50 GHz, are Predicted by numerical calculations.     

双漂移(P+PNN+)雪崩二极管的计算机辅助分析

本文报道了8mm硅双漂移雪崩二极管的计算机计算结果,并把双漂移器件与单漂移(P⁺NN⁺型)器件进行了比较,从而证实双漂移器件在输出功率和效率等方面都具有优越性,同时还研究了掺杂分布、温度、直流偏置和高频调制电压对器件特性的影响。本文为设计毫米波段双漂移雪崩二极管振荡器和放大器提供了理论数据。     

High-power generation in IMPATT devices in the 100-200-GHz range

A silicon double-drift IMPATT diode with high uniform doping levels was simulated. Simulation results show that it is possible for silicon IMPATT diodes to generate extremely high pulsed output power for frequencies above 100 GHz under high current-density operation. The highest output power matched to a 1-Ω load resistance obtained at 150 GHz is 37.7 W with a DC current density of 200 kA/cm², although the calculated power conversion efficiency is low. It is also shown that the low-power conversion efficiency limits the diode's continuous wave power operation     

Ion-implanted double-drift Ka-band diodes

The application of a doubly charged boron (¹¹B⁺²) beam to the formation of p-type drift regions in symmetrical Ka-band double-drift silicon IMPATT diodes is discussed. Devices fabricated with these implanted impurity distributions exhibited output powers ∼1.2 W with 10-percent conversion efficiencies over the frequency range of 29 to 39 GHz.     

Electron and hole ionization rates in epitaxial silicon at high electric fields

Ionization rates for electrons and holes are extracted from photomultiplication measurements on silicon p⁺n mesa diodes for electric fields of 2·0 × 10⁵?7·7 × 10⁵ V/cm at temperatures of 22, 50, 100 and 150°C. These results are particularly pertinent to the analysis of high-frequency (～ 100 GHz) silicon IMPATT diodes.The rates obtained here are in reasonable agreement with previously published data of van Overstraeten and DeMan, although slightly larger in magnitude. Calculated curves of breakdown voltage vs background doping level are presented using the room temperature ionization rates. Also a comparison is made to previously reported rates. The new rates provide a closer agreement between predicted and measured breakdown voltages for breakdown voltages less than 70 V.     

High-power millimeter wave IMPATT oscillators with both hole and electron drift spaces made by ion implantation

CW powers of 640 mW at 50 GHz have been obtained from double-drift region IMPATT diodes. This result represents the highest product of CW power times frequency squared obtained to date from any IMPATT diode. The diodes are p⁺pnn⁺structures and have both hole and electron drift spaces. The systematic fabrication (by ion implantation) and the evaluation of the dc and millimeter wave characteristics are presented.     

High-power operation mode of pulsed IMPATT diodes

Pulsed silicon double-drift IMPATT diodes that yield 42 W at 96 GHz are discussed. This is about twice the value reported previously. Owing to the considerable input powers (≈500 W), these diodes are mounted on diamond heat sinks. Because of the strong carrier injection, the field distribution in the diode is similar to that in a p-i-n diode. An attempt is made to explain the results using T. Misawa's (1966) p-i-n type theory. The large-signal; avalanche resonant frequency is close to the operation frequency. Conventional Read-type theory fails to explain these results because of the current densities employed in the experiments     

Circuit representation of avalanche region of IMPATT diodes for different carrier velocities and ionisation rates of electrons and holes

A parallel resonant circuit representing the small-signal behaviour of the avalanche region of IMPATT diodes is given. The components are calculated in a nonquasistatic manner for different ionisation rates and drift velocities of electrons and holes. With the results, the avalanche frequencies of Si, Ge and GaAs as functions of the avalanche zone width are compared.     

Power-generation potential of various IMPATT structures from a scaling approximation

The power potential of the double-drift and both complementary 1-sided silicon IMPATTS is estimated as a function of frequency, using a scaling approximation that accounts for the dependence of generation efficiency on bias-current density. The results show the n+?p junction IMPATT to be a superior choice for reliable power generation below 25 GHz, owing to its relatively low threshold-current density.     

Nonlinear properties of IMPATT devices

The basic principles of IMPATT diodes as microwave devices are reviewed and the current status of these devices concerning power output and efficiency is given. The main purpose of this paper, however, is to discuss the nonlinear properties of these diodes which are useful in the design of amplifiers, oscillators, and other microwave devices. The main results of this paper are obtained from a digital computer analysis where an approximate, but realistic, diode model is employed. A detailed comparison of complementary silicon diodes as well as GaAs diodes concerning power output and efficiency is given. The effects of doping profile, current density, temperature, and material parameters on the performance of these devices have been investigated and are summarized. Saturation effects which limit the efficiency and power output of these devices are described and optimum efficiencies which can be achieved for various doping profiles are given. A comparison between single-sided and double-drift diodes in both silicon and GaAs is also presented.     

IMPATT oscillators with enhanced leakage current

The behavior of IMPATT oscillators with enhanced leakage current has been experimentally evaluated by irradiating operating diodes with transient ionizing radiation. Leakage current was induced in diffused junction GaAs and silicon X-band IMPATT diodes by irradiation with 100 nsec pulses of 10 MeV electrons. With increasing leakage current, the oscillator RF power decreases and the frequency of oscillation increases. A large signal circuit model of the IMPATT diode is developed which correlates well with experimental measurements.     

Recent advances in device processing and packaging of high-power pulsed GaAs double-drift IMPATT's at X-band

High-power multimesa GaAs hybrid double-drift IMPATT's have been developed for pulsed operation at X-band. The diodes are fabricated from GaAs material grown by a novel "infinite" solution liquid phase epitaxial process. The use of specialized rapid thermal processing and packaging techniques has enabled the fabrication of high-power IMPATT oscillators that have delivered peak output powers of over 40 W with 20-percent efficiency under pulsed RF operation at X-band frequencies. The diodes are constructed with an integral heat sink and bounded with a Au-Sn eutectic solder in a microwave package.     

High Peak Pulse Power Silicon Double-Drift IMPATT Diodes

The performance of high peak pulse power silicon double-drift IMPATT devices operated at medium pulse repetition frequency are discussed. Several devices were characterized and achieved more than 45-W peak pulse power with 10-percent duty cycle at 9.7 GHz. Conversion efficiencies in the order of 9.7-11.2 percent were observed. These results compare with previously reported 19-W peak power, 10-percent duty-cycle, and 9.5-percent efficiency.