Showing papers on "IMPATT diode published in 2020"

Demonstration of GaN Impact Ionization Avalanche Transit-Time (IMPATT) Diode

Abstract: Wide bandgap semiconductors, such as gallium nitride (GaN) and silicon carbide (SiC), have bandgap energies larger than 3 eV with high breakdown electric fields, showing the advantage on powerful IMPATT diodes. SiC IMPATT diodes have been successfully demonstrated and shown excellent performances in X-band applications [1] , [2] . Although a few theoretical studies have shown the great potential of GaN for powerful IMPATT diodes [3] , [4] , no experimental study has been reported so far. Taking advantage of the single crystalline GaN substrates enabling high quality GaN films, avalanche capability has been demonstrated [5] – [9] . In this study, we demonstrated a GaN-based IMPATT diode experimentally by using a n-i-p epitaxial structure grown on a bulk GaN substrate.

Multi-Stage-Multi-Iterative Optimization Algorithm for Design Optimization of Multi-Quantum Well Terahertz IMPATT Sources

Abstract: A multi-stage-multi-iterative optimization (MSMIO) algorithm has been proposed in this paper for optimizing the design parameters of MQW DDR IMPATT diode based terahertz (THz) sources based on Al x Ga 1-x N~GaN heterostructures. The optimization has been carried out subject to achieve favourable large-signal (L-S) as well as avalanche noise characteristics of the source designed to operate at 1.0 THz. Six major parameters associated with the MQW structure, such as (i) mole fraction of Al in Al x Ga 1-x N, (ii) thickness of Al x Ga 1-x N layers, (iii) corresponding doping concentrations, (iv) thickness of GaN layers, (v) corresponding doping concentrations and (vi) bias current density are optimized subject to attain highest efficiency as well as lowest noise measure of the 1.0 THz source. The L-S and noise characteristics of optimized as well as un-optimized MQW DDR structures are compared in order to verify the proficiency of the algorithm; comparison is also done between simulation and experimental results of 1.0 THz oscillators based on other semiconductors reported earlier.

A Study on the Noise Performance of an Si based IMPATT Device for Different Junction Temperature

Abstract: The influence of temperature on avalanche noise measure of Double Drift Region (DDR) Si based IMPATT(Impact Ionisation Avalanche Transit Time) device has been studied in this paper. The double iterative method for drift-diffusion model has been used for the calculation of Noise Measure and finally the Noise Spectral Density of the IMPATT Diode. Linear variation of noise measure with temperature has been observed here. From the simulation it is seen that with the increase in junction temperature the noise performance improves and the device is much more effective in use.

Parasitic Series Resistance for 4H-SiC and Diamond-Based IMPATT Diode at Ku Band

Abstract: In this work, parasitic series resistance (Rs) has been computed for IMPATT using 4H-SiC and diamond at Ku band. Rs is calculated from the conductance- susceptance profile of the IMPATT. Rs of 4H-SiC was found to be less than diamond at the corresponding frequency. As 4H-SiC is having lesser Rs value than diamond, it can deliver more power to the output RF circuit as compared to diamond-based IMPATT diode.

Improvement of Thermal Endurance for Integrated Millimeter-Wave Silicon IMPATT Device in µm2-Scale

Abstract: Based on the fact that the avalanche frequency of impact-ionization avalanche transit-time (IMPATT) diode is proportional to the square-root of DC biasing current density, more DC current injection is necessary to push the negative differential resistances (NDRs) into higher frequency regime. This leads to a serious thermal endurance problem for IMPATT devices in monolithic integration scenario, since the pn-junction area reaches only µm2-scale compared to traditional discrete cases of mm2-scale and on the other side there is lack of huge heat sink commonly applied in each discrete IMPATT component design. After characterizing series of fabricated IMPATT devices with pn-junction area of 30 × 2 µm2; 30 × 4 µm2; 30 × 6 µm2; 30 × 10 µm2, their avalanche frequencies haven been extracted and plotted over varied square-root of DC biasing current densities. The discrepancy between the estimated and measured profiles has confirmed and explained exactly the usually ignored temperature effect. Scanning electron microscopy (SEM) images have been taken for a burned out IMPATT diode of 30 × 2 µm2. The weak point did not occur at the expected “fragile” pn-junction, but at the metallic interconnect. This triggered an improvement of a new device layout design. The SEM images of two IMPATT diodes with the same pn-junction (30 × 2 µm2) but different layouts in the burn-out test verifies the improvement of device thermal endurance. Additionally, the IMp ATT diode with the new layout design offered 7 mA more regarding the maximum injected DC biasing current than the one with old layout design. This ensures the overall device robustness regarding thermal endurance for further circuit design.

IMPATT Efficiency Extraction Using On-Chip Antenna Radiation

Abstract: IMPATT diodes were designed and integrated with microstrip patch antenna on-chip in standard CMOS technology to extract the efficiency beyond avalanche frequency. By comparing the on-chip simulations and measurements of an IMPATT diode integrated in a CPW to an integrated one with a microstrip patch antenna at the same biasing conditions, the results demonstrated an efficiency ranging from ∼ 0.01% to 0.016% without and with the added surface roughness losses, respectively. Such variation is strongly associated with the uncertainty provided by the increase of conduction losses ranging between 40%∼80% beyond the avalanche frequency.

Homotype heterostructure IMPATT diode and manufacturing method thereof

Abstract: The invention discloses a homotype heterostructure IMPATT diode and a manufacturing method thereof. The IMPATT diode comprises an n-type GaN substrate, an n++-GaN cathode ohmic contact layer, an n-GaNdrift region, an n+-GaN avalanche region, an n++-InGaN anode ohmic contact layer and an anode which are sequentially arranged from bottom to top. The passivation layer is located outside the anode, and the cathode is located on the upper layer of an annular table top formed by the n++-GaN cathode ohmic contact layer2 and located outside the passivation layer. Compared with a traditional GaN-basedIMPATT diode, the homotype heterostructure IMPATT diode adopting the homotype heterogeneous material has the advantages that the limitation of a P-type GaN doping process is avoided, the efficiency of the IMPATT diode is linearly improved along with the increase of the doping concentration of an InGaN material, and high conversion efficiency is realized; according to the invention, n-type semiconductor materials are adopted, i.e., n-type doping is adopted, so that the efficiency of the manufacturing process is improved, the manufacturing cost is reduced, and meanwhile, the manufacturing process is completely compatible with the traditional IMPATT diode packaging process.

Transverse-structure IMPATT diode and preparation method thereof

Abstract: The invention discloses a transverse-structure IMPATT diode and a preparation method of the IMPATT diode. The IMPATT diode includes: a substrate layer, an epitaxial layer, a drift layer, an n-AlGaN barrier layer, an n+-GaN barrier layer, a left ohmic contact layer, a right ohmic contact layer, a left ohmic contact electrode, a right ohmic contact electrode, a passivation layer and a Schottky contact electrode. When the transverse-structure IMPATT diode is electrified, the current direction is along the transverse direction of the epitaxial layer; the drift layer is a two-dimensional electrongas thin layer formed on the top of the epitaxial layer, and the transition process is limited in the drift layer rather than in a body material. The IMPATT provided by the invention improves the oscillation frequency, the transverse circuit compatibility and the frequency flexibility compared with a traditional vertical-structure IMPATT by utilizing a transverse structure under the same material.

Optimal Design of Large Signal Performance of AlN/GaN Hetero-Structural IMPATT and MITATT Diodes

Abstract: Hetero-structure of AlxGa1-xN/GaN exhibits important applications in high frequency and large power devices. In this paper, AlN/GaN is adopted to optimal design the large power impact avalanche transit time (IMPATT) and mixed tunneling avalanche transit time (MITATT) diodes operating at the atmospheric low loss window frequency of 0.85 THz. The static state and large signal characteristics of the devices are numerically simulated. The values of peak electric field strength, break-down voltage, avalanche voltage, the maximum generation rates of avalanche and tunneling, admittance-frequency relation, output power, conversion efficiency, quality factor of the proposed hetero-structural IMPATT and MITATT diodes are calculated, respectively. Via comparing the obtained results of (n)AlN/(p)GaN and (n)GaN/(p)AlN IMPATT diodes to those of the MITATT counterparts, there exists little performance difference between IMPATT and MITATT devices while implies significant difference between the (n)AlN/(p)GaN and (n)GaN/(p)AlN diodes.