The authors have developed a quantum corrected drift-diffusion model for impact avalanche transit time (IMPATT) devices by coupling the density gradient model with the classical drift-diffusion model. A large-signal simulation technique has been developed by incorporating the quantum potentials in the current density equations for the analysis of double-drift region IMPATT devices based on different semiconductors such as Wurtzite---GaN, InP, type-IIb diamond (C), 4H---SiC and Si deigned to operate at different millimeter-wave (mm-wave) and terahertz (THz) frequencies. It is observed that, the RF power output and DC to RF conversion efficiency of the devices operating at higher mm-wave ($$>$$>140 GHz) and THz frequencies reduce due to the incorporation of quantum corrections in the model; but the effect of quantum corrections are negligible for the devices operating at lower mm-wave frequencies ($$\le $$≤140 GHz).

Quantum corrected drift-diffusion model for terahertz IMPATTs based on different semiconductors

Quantum correction is necessary on the classical drift-diffusion (CLDD) model to predict the accurate behavior of high frequency performance of ATT devices at frequencies greater than 200 GHz when the active layer of the device shrinks in the range of 150---350 nm. In the present work, a quantum drift-diffusion model for impact avalanche transit time (IMPATT) devices has been developed by incorporating appropriate quantum mechanical corrections based on density-gradient theory which macroscopically takes into account important quantum mechanical effects such as quantum confinement, quantum tunneling, etc. into the CLDD model. Quantum potentials (synonymous as Bohm potentials) have been incorporated in the current density equations as necessary quantum mechanical corrections for the analysis of millimeter-wave (mm-wave) and Terahertz (THz) IMPATT devices. It is observed that the large-signal (L-S) performance of the device is degraded due to the incorporation of quantum corrections into the model when the frequency of operation increases above 200 GHz; while the effect of quantum corrections are negligible for the devices operating at lower mm-wave frequencies.

Quantum drift-diffusion model for IMPATT devices

An attempt is made in this paper to explore the potentiality of semiconducting type-IIb diamond as the base material of double-drift region (DDR) impact avalanche transit time (IMPATT) devices operating at both millimetre-wave (mm-wave) and terahertz (THz) frequencies. A rigorous large-signal (L-S) simulation based on the non-sinusoidal voltage excitation (NSVE) model developed earlier by the authors is used in this study. At first, a simulation study based on avalanche response time reveals that the upper cut-off frequency for DDR diamond IMPATTs is 1.5 THz, while the same for conventional DDR Si IMPATTs is much smaller, i.e. 0.5 THz. The L-S simulation results show that the DDR diamond IMPATT device delivers a peak RF power of 7.79 W with an 18.17% conversion efficiency at 94 GHz; while at 1.5 THz, the peak power output and conversion efficiency decrease to 6.19 mW and 8.17% respectively, taking 50% voltage modulation. A comparative study of DDR IMPATTs based on diamond and Si shows that the former excels over the later as regards high frequency and high power performance at both mm-wave and THz frequency bands. The effect of band to band tunneling on the L-S properties of DDR diamond and Si IMPATTs has also been studied at different mm-wave and THz frequencies.

https://iopscience.iop.org/article/10.1088/1674-4926/35/3/034005/pdf

Potentiality of semiconducting diamond as the base material of millimeter-wave and terahertz IMPATT devices

The influence of inter-carrier scattering phenomena on the noise performance of double-drift region (DDR) impact avalanche transit time diodes has been investigated. Three optimized Si DDR ...

Influence of Carrier–Carrier Interactions on the Noise Performance of Millimeter-Wave IMPATTs

A major amount of energy of mobile electrons and holes in a semiconductor under electric field are lost due to inter-carrier collisions prior to ionising collision. This fact causes a decrease in the ionisation probability which leads to the deterioration in ionisation rates especially when the doping density is high. The effects of this phenomenon on the high frequency and noise properties of highly doped impact avalanche transit time (IMPATT) devices based on different wide bandgap (WBG) semiconductors, like 4H-SiC, Wurtzite-GaN (Wz-GaN) and type-IIb diamond (C) have been studied in this paper. Significant deteriorations in the diodes' high frequency and noise performance have been observed in the simulation results. The simulation results have been compared with the experimental data in order to validate those.

Millimetre-wave and terahertz IMPATT sources: influence of inter-carrier interactions

Large-signal simulation is carried out in this paper to investigate the prospects and potentiality of Double-Drift Region (DDR) Impact Avalanche Transit Time (IMPATT) device based on semiconducting type-IIb diamond as millimeter-wave source operating at 94 GHz atmospheric window frequency. Large-signal simulation method developed by the authors and presented in this paper is based on non-sinusoidal voltage excitation. The simulation is carried out to obtain the large-signal characteristics such as RF power output, DC to RF conversion efficiency etc. of DDR diamond IMPATT device designed to operate at 94 GHz. The results show that the device is capable of delivering a peak RF power output of 7.01 W with 10.18% DC to RF conversion efficiency for a bias current density of 6.0×10 Am and voltage modulation of 60% at 94 GHz; whereas for the same voltage modulation 94 GHz DDR Si IMPATT can deliver only 693.82 mW RF power with 8.74 efficiency for the bias current density of 3.4×10 Am.

/pdf/diamond-based-ddr-impatts-prospects-and-potentiality-as-19tu8c5mwb.pdf

M. Sarkar

Papers

Diamond Based DDR IMPATTs: Prospects and Potentiality as Millimeter-Wave Source at 94 GHz Atmospheric Window