Showing papers on "IMPATT diode published in 2021"

Experimental demonstration of GaN IMPATT diode at X-band

Abstract: We report the first experimental demonstration of microwave oscillation in GaN impact ionization avalanche time transit (IMPATT) diodes at the X-band. The device used in this study is a single drift diode with a p+–n simple abrupt junction and vertical mesa termination. The reverse I–V characteristic of the diode shows low leakage current, clear avalanche breakdown, and high avalanche capability, as required for IMPATT operation. Microwave testing is performed in an X-band waveguide circuit with a reduced-height waveguide resonant cavity. Oscillations are observed at 9.52 GHz at a power of ∼56 mW.

Study of p-SiC/n-GaN Hetero-Structural Double-Drift Region IMPATT Diode.

Abstract: Nowadays, the immature p-GaN processes cannot meet the manufacturing requirements of GaN impact ionization avalanche transit time (IMPATT) diodes. Against this backdrop, the performance of wide-bandgap p-SiC/n-GaN heterojunction double-drift region (DDR) IMPATT diode is investigated in this paper for the first time. The direct-current (DC) steady-state, small-signal and large-signal characteristics are numerically simulated. The results show that compared with the conventional GaN single-drift region (SDR) IMPATT diode, the performance of the p-SiC/n-GaN DDR IMPATT proposed in this design, such as breakdown voltage, negative conductance, voltage modulation factor, radio frequency (RF) power and DC-RF conversion efficiency have been significantly improved. At the same time, the structure proposed in this design has a larger frequency bandwidth. Due to its greater potential in the RF power density, which is 1.97 MW/cm2 in this study, indicates that the p-SiC/n-GaN heterojunction provides new possibilities for the design and manufacture of IMPATT diode.

Study of In x Ga 1- x N/GaN Homotype Heterojunction IMPATT Diodes

Abstract: In this work, a novel n-In x Ga1- x N/N-gallium nitride (GaN) homotype heterostructure is proposed instead of P-GaN/N-GaN homostructure to produce impact-ionization-avalanche-transit-time (IMPATT) diode. Conventional GaN IMPATT device will lose its working ability due to the immature p-type GaN, so this work predicts that the n-In x Ga1- x N/N-GaN IMPATT diode can be an alternative to the GaN p-n IMPATT diode; thus, the difficulty of the p-type doping process is avoided. The dc and RF large-signal output characteristics with different compositions are investigated in detail. The simulation results show that the power and efficiency of the novel structure device increase when the In composition increases. When the In composition is greater than 0.4, the performance of the homotype heterojunction IMPATT is better than that of p-n IMPATT. Moreover, homotype heterojunction IMPATT is better in frequency bandwidth, and it can hold greater bias current density than p-n IMPATT. Meanwhile, the performance of homotype heterojunction IMPATT does not depend on the thickness of the InGaN layer, but it decreases as the thickness of the p-type region in p-n IMPATT increases. As it has greater potential in the application, this work brings a reference for the design and manufacture of IMPATT devices based on wide bandgap semiconductor materials, especially GaN materials.

A Novel Integrated Power Module with Solid-State Diode at THz Frequency—The Concept and a Possible Way to Realize It

Abstract: The basic concept and possible way to realize a novel power module with device and antenna integrated in the same structure using IMPATT diode has been proposed that might have useful applications at THz frequency. The power module judiciously used the idea of resonant-cap cavity for oscillator design normally used at microwave and millimetre–wave frequency, slotted disc for broadband operation and an improvised circular microstrip patch antenna integrated in the same structure. The structure is realizable with fully planer technology with some added steps in the device fabrication process. Since there is no need for transmission line or waveguide to connect the antenna with the oscillator, the transmission loss is minimized and the integrated structure will also lead to size miniaturization. The integrated power module is expected to have many applications especially at THz frequency regime.

Study on Electric Field Modulation and Avalanche Enhancement of SiC/GaN IMPATT Diode

Abstract: This paper proposes a 6H-materials silicon carbide (SiC)/gallium nitride (GaN) heterogeneous p-n structure to replace the GaN homogenous p-n junction to manufacture an impact-ionization-avalanche-transit-time (IMPATT) diode, and the performance of this 6H-SiC/GaN heterojunction single-drift-region (SDR) IMPATT diode is simulated at frequencies above 100 GHz. The performance parameters of the studied device were simulated and compared with the conventional GaN p-n IMPATT diode. The results show that the p-SiC/n-GaN IMPATT performance is significantly improved, and this is reflected in the enhanced characteristics in terms of operating frequency, rf power, and dc-rf conversion efficiency by the two mechanisms. One such characteristic that the new structure has an excessive avalanche injection of electrons in the p-type SiC region owing to the ionization characteristics of the SiC material, while another is a lower electric field distribution in the drift region, which can induce a higher electron velocity and larger current in the structure. The work provides a reference to obtain a deeper understanding of the mechanism and design of IMPATT devices based on wide-bandgap semiconductor materials.

A Brief Review on Terahertz Avalanche Transit Time Sources

Abstract: During last few years, numerous researches have been processed for the growth of reliable sources in the terahertz (THz) frequency regime. Among different solid-state sources, impact ionization avalanche transit time (IMPATT) diode is the most promising one for THz wave generation. Here, a selective review has been carried on THz IMPATT diode, which helps in detailed understanding of device operation in this domain. The paper mainly deals with several terahertz properties based on DC, noise, small and large-signal simulation of IMPATT devices. This study reveals the potency of this device in many THz applications.

Wide bandgap semiconductor heterojunction transit time diode noise detection method and system

Abstract: The invention provides a wide bandgap semiconductor heterojunction transit time diode noise detection method and system. The method comprises the steps that: a to-be-detected diode (DUT) is obtained,corresponding noise factors which comprise an ionization avalanche effect, a quantum effect and a field tunneling effect are selected, and a preset continuity equation, a current density equation anda Poisson equation are corrected, wherein the DUT is a collision ionization avalanche transit time IMPATT diode or a mixed tunneling avalanche transit time MITATT diode; the DUT model is gridded, andan equation set consisting of the corrected continuity equation, current density equation and Poisson equation is discretized; the discretized equation set is solved, so that a structure, steady-stateperformance and alternating-current performance can be obtained; and a noise model is constructed, and the structure, steady-state performance and alternating-current performance parameter values areimported into the noise model and boundary conditions so as to be subjected to double iterative computation to obtain a noise parameter value of the DUT. With the wide bandgap semiconductor heterojunction transit time diode noise detection method and system of the embodiment of the invention adopted, the noise detection precision of the DUT can be improved.

Effects of Space Charges in IMPATT Source at Terahertz Regime

Abstract: Impact ionization and avalanche transit time (IMPATT) operation is based on impact ionization and avalanche multiplication of charge carriers. However, its operation is affected by the extra charges created in the space charge region. The effect due to generation of extra charges is called as space charge effect. The space charge effect in IMPATT can be numerically analyzed in the form of disturbance in the actual electric field profile. In this chapter, authors have studied the space charge effects in the double drift region (DDR) IMPATT based on Si, Ge, and GaAs at frequency of 1–30 THz. Disturbances in the electric field profile, and drift voltages have been analyzed here with analysis of resistances offered due to space charge effects. This study will be helpful for optimum design of IMPATT diode at THz against space charge effects.

Analysis of Electrical and Thermal Models for Pulsed IMPATT Diode Simulation

Abstract: Some nonlinear models are presented for modeling and analyzing IMPATT high-power pulse diodes. These models are suitable for analyzing different operating modes of the oscillator. The first model is a precise one, which describes all important electrical phenomena on the basis of the continuity equations and Poisson´s equation, and it is correct until 300 GHz. The second approximate mathematical model suitable for the analysis of IMPATT diode stationary operation oscillator and for optimization of internal structure of the diode. The temperature distribution in the semiconductor structure is obtained using the special thermal model of the IMPATT diode, which is based on the numerical solution of the non-linear thermal conductivity equation. The described models can be applied for the analysis, optimization and practical design of pulsedmode millimetric IMPATT diodes. It can also be used to evaluate the thermal behavior of diodes, to correctly select the shape and amplitude of a supply pulse, and to design various types of high-power pulsed millimeter IMPATT diodes with a complex doping profile with improved characteristics.

Material Systems for Realizing Heterojunction IMPATT Sources for Generating Terahertz Waves

Abstract: Impact ionization avalanche transit time (IMPATT) diode is a microwave semiconductor device which also is an emerging solid-state source that generates high power and high DC to RF conversion efficiency at frequencies from 0.30 to 10.0 THz. Compare to the conventional flat Si IMPATT source, the simulation results of a self-consistent quantum drift–diffusion (SCQDD) model show that Si ~ 3C-SiC MQW IMPATT source can provide considerably higher RF output power with notably lower noise measure for millimeter-wave (mm-wave) and terahertz (THz) frequency bands. The wide bandgap (WBG) materials like SiC, GaN and diamond are used as base materials of IMPATT diode that gives relatively high frequency and high power at mm-wave and THz range, i.e., from 0.1 to 10 THz. The ionization rate and saturation limitation can be avoided in MQW structures, whereas in conventional IMPATTs the DC to RF conversion efficiency falls significantly at higher mm-wave frequencies due to the saturation of ionization rate of charge carriers at high electric fields. IMPATT devices are applied as solid-state transmitters in tracking radars, missile guidance, and mm-wave communication systems, etc.

Performance of 4H-SiC IMPATT Diode at Ka- and W-Band with Temperature Variation

Abstract: We have carried out the DC analysis of one-dimensional n+-n-p-p+ structure and its temperature dependency for 4H-SiC IMPATT diode at 36 GHz and 94 GHz. Efficiency, noise, and various dc parameters at different junction temperatures are computed and compared by taking the area of the diode as 10−8m2 (material measurement data). This paper can be helpful to choose the best operating condition for 4H-SiC and designing the 4H-SiC-based IMPATT diode against temperature variation at Ka-band and W-band.