Computer studies have been made on the high frequency characteristics of symmetrically doped flat profile double drift region (DDR) InP and GaAs impatts in the mm-wave (60-100 GHz) frequency band. The spatial distribution of high frequency negative resistance and reactance in the depletion layer of DDR devices and their admittance properties have been investigated. The results indicate that DDR InP impatts should have higher drift zone voltage drop, higher negative resistance and higher negative conductance compared to their GaAs counterparts designed for the same range of mm-wave frequencies. Furthermore, the negative resistance peak is larger in magnitude for InP impatts compared to that for GaAs impatts. It is thus observed that DDR InP impatts should be superior to their GaAs counterparts as regards mm-wave power generation with high conversion efficiency. © 1989 Springer-Verlag.

J P BANERJEE

S P PATI

S K ROY

University of Calcutta (informally known as Calcutta University or CU) is a collegiate public state university located in Kolkata, West Bengal, India.&nbsp;Within India it is recognized as a &quot;Five-Star University&quot; and accredited &quot;A&quot; Grade by National Assessment and Accreditation Council.

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The University of Calcutta has secured the Fifth position among the Universities of India in the prestigious &quot;Indian University Ranking 2019&quot; list, released by the NIRF of the Ministry of Human Resource Development, Government of India.

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It was established on 24 January 1857, and was one of the first institutions in Asia to be established as a multidisciplinary and Western-style university. Its alumni and faculty include several heads of state, heads of government, social reformers, prominent artists, only academy award winner and Dirac medal winner in India, many Fellows of the Royal Society and five Nobel laureates as of 2019 which is highest in South Asia.

University Of Calcutta

High frequency characterisation of double drift region InP and GaAs diodes

Applied Physics A Solids and Surfaces

The effects of elevated junction temperature on the terahertz (THz) frequency characteristics of α-(hexagonal, 4H and 6H) silicon carbide (SiC) based double-drift region (DDR, p++ p n n++ type) impact ionization avalanche transit-time (IMPATT) devices are studied and compared for the first time through simulation experiments. This study reveals that at 300 K &lt; T &lt; 600 K, a 4H-SiC IMPATT diode may yield 3.5 W of output power (efficiency (η) ∼ 8.6%) at 1.3 THz, while its 6H-SiC counterpart can deliver 3 W of output power (η = 6.3%) at 1.2 THz. It is interesting to observe that at elevated temperature, the performance of a 6H-SiC IMPATT diode degrades more in comparison with its 4H-SiC counterpart. These comparative analyses reveal the superiority of 4H-SiC diodes over their 6H-SiC counterparts, and thus establish the potential of the former as a high-power THz IMPATT oscillator even in harsh environments. Mobile space charge effects and the effect of positive series resistance on the high-temperature performance of the THz devices are also simulated, and it is found that series resistance reduces the output power level of the diodes by at least 15.0%. Moreover, the effects of increased junction temperature on the photo-sensitivity of top mounted (TM) and flip chip (FC) α-SiC IMPATTs are also investigated using a modified simulation technique. The device operating frequencies, under TM illumination configuration, shifts upward by at least 40.0 GHz, whereas the operating frequency shifts upward by at least 100.0 GHz under FC illumination configuration. The simulation results and the proposed experimental methodology presented here may be used for realizing optically controlled α-SiC transit-time devices for application in THz communication. © 2010 IOP Publishing Ltd.

Semiconductor Science and Technology

Î±-SiC nanoscale transit-time diodes: Performance of the photo-irradiated terahertz sources at elevated temperature

The effects of elevated junction temperature on the terahertz (THz) frequency characteristics of alpha-(hexagonal, 4H and 6H) silicon carbide (SiC) based double-drift region (DDR, p(++) p n n(++) type) impact ionization avalanche transit-time (IMPATT) devices are studied and compared for the first time through simulation experiments. This study reveals that at 300 K < T < 600 K, a 4H-SiC IMPATT diode may yield 3.5 W of output power (efficiency (eta) similar to 8.6%) at 1.3 THz, while its 6H-SiC counterpart can deliver 3 W of output power (eta = 6.3%) at 1.2 THz. It is interesting to observe that at elevated temperature, the performance of a 6H-SiC IMPATT diode degrades more in comparison with its 4H-SiC counterpart. These comparative analyses reveal the superiority of 4H-SiC diodes over their 6H-SiC counterparts, and thus establish the potential of the former as a high-power THz IMPATT oscillator even in harsh environments. Mobile space charge effects and the effect of positive series resistance on the high-temperature performance of the THz devices are also simulated, and it is found that series resistance reduces the output power level of the diodes by at least 15.0%. Moreover, the effects of increased junction temperature on the photo-sensitivity of top mounted (TM) and flip chip (FC) alpha-SiC IMPATTs are also investigated using a modified simulation technique. The device operating frequencies, under TM illumination configuration, shifts upward by at least 40.0 GHz, whereas the operating frequency shifts upward by at least 100.0 GHz under FC illumination configuration. The simulation results and the proposed experimental methodology presented here may be used for realizing optically controlled alpha-SiC transit-time devices for application in THz communication.

alpha-SiC nanoscale transit-time diodes: performance of the photo-irradiated terahertz sources at elevated temperature

Extensive simulation experiments are carried out for the first time, to study the optical modulation of the high- frequency characteristics of III-V GaN-(gallium nitride) based top-mounted and flip-chip IMPact Avalanche Transit Time (IMPATT) oscillators at MM-wave window frequency (140.0GHz). It is found that the un-illuminated GaN IMPATT is capable of delivering a RF power of 5.6 W with an efficiency of 23.5% at 145.0GHz. Frequency up-chirping of 6.0GHz and a degradation of RF power output by almost 15.0% are further observed in case of photo-illuminated FC IMPATT. The study reveals that compared to predominate electron photocurrent in top-mounted IMPATT, photo-generated leakage current dominated by hole in flip-chip IMPATT has more pronounced effect on the GaN-based device as regards the frequency chirping and decrease of negative conductance and total negative resistance per unit area of the device. The inequality in the magnitudes of electron and hole ionization rates in the wide band gap semiconductor has been found to be correlated with the above results. The study reveals that GaN IMPATT is a potential candidate for replacing conventional IMPATTs at high-frequency operation. These results are useful for practical realization of optically controlled GaN-based high-power IMPATTs for application in MM-wave communication systems. © 2010 Cambridge University Press and the European Microwave Association.

International Journal of Microwave and Wireless Technologies

Optically modulated III-V nitride-based high-power IMPact Avalanche Transit Time oscillator at Millimeter-wave window frequency

High-frequency analysis has been carried out to predict the rf performance of 〈111〉, 〈110〉 and 〈100〉 oriented p+nn+, n+pp+ (single drift region) and n+npp+ (double drift region) GaAs IMPATT diodes for opertion at 35 and 60 GHz. The microwave performance is observed to be highly sensitive to crystal orientation in case of p+nn+ and n+npp+ diodes whereas orientation of the substrate has negligible effect on n+pp+ avalanche diodes. The calculation shows that 〈111〉 oriented GaAs IMPATT diode would provide the largest magnitude of negative resistance and negative conductance for both SDR p+nn+ and DDR n+npp+ diodes which indicates that high microwave power with high conversion efficiency can be realised from these 〈111〉 oriented GaAs devices. This result can be explained from the experimental data of electron and hole ionization rates for different orientations in GaAs. © 1993 Springer-Verlag.

Studies on the high-frequency properties of ã€ˆ111ã€‰, ã€ˆ110ã€‰ and ã€ˆ100ã€‰ oriented GaAs IMPATT diodes

A generalized small-signal computer simulation of double avalanche region (DAR) n+-p-v-n-p+ Si and InP IMPATT diodes has been carried out for different frequencies and current densities taking both drift and diffusion of charge carriers into account. The simulation results show that both symmetrically and asymmetrically doped devices based on Si and InP exhibit discrete negative conductance frequency bands separated by positive conductance frequency bands. The magnitudes of both negative conductance and negative resistance of InP devices are larger than those of Si devices in case of symmetrical and asymmetrical diodes. Further, the negative resistance profiles in the depletion layer of these diodes exhibit a single peak in the middle of the drift layer in contrast to double peaks in double drift region diodes. © 1993 Springer-Verlag.

Computer simulation of the small-signal admittance and negative resistance of double avalanche region IMPATT diodes

A computer study on the dc field and current-density profiles of a Si n+-p-v-n-p+ double avalanche region (DAR) Impatt has been carried out. With increasing current density the uniform electric field in the central drift region remains almost unaffected due to cancellation of mobile space charge, in case of symmetrically doped structure. Also the avalanche and drift-zone widths and the RF conversion efficiency remain almost unaltered. For asymmetric doping there is a small space-charge effect. Copyright © 1982 by The Institute of Electrical and Electronics Engineers, Inc.

Journal	Data powered by TypesetApplied Physics A Solids and Surfaces
Publisher	Data powered by TypesetSpringer-Verlag
ISSN	0721-7250