J. K. Mishra

An extremely low noise heterojunction IMPATT

The avalanche noise characteristics of InP/GaInAs (Ga/sub 0.47/In/sub 0.53/As) and InP/GaInAsP (Ga/sub 0.33/In/sub 0.67/As/sub 0.7/P/sub 0.3/) double drift region (DDR) heterostructure IMPact Avalanche Transit Time (IMPATTs) have been studied. The heterostructure IMPATTs in general are found to be less noisy compared to their homostructure counterparts and in particular the InP/GaInAs DDR is found to generate extremely low noise when the ternary layer width is properly selected. A noise measure of 7.7 dB has been observed at 190 GHz for a GaInAs layer width of 140 nm. Further, a study on the noise contribution from the individual space steps of the depletion layer due to individual noise sources in the generation region has revealed some interesting differences between those of homostructure and heterostructure diodes. Finally, a criterion for low-noise design is also suggested.

Prospects of 6H-SiC for operation as an IMPATT diode at 140 GHz

The potentials of 6H-SiC are explored for application as a high power IMPATT diode through computer simulation experiment. It is observed that the new material would far surpass its present rivals Si and GaAs in terms of power output at 140 GHz. However, excessive noise would put a severe restriction on the applicability of 6H-SiC for high-efficiency IMPATT structures.

Noise in mixed tunneling avalanche transit time (MITATT) diodes

Abstract A generalized method of analysis for avalanche noise in mixed tunneling and avalanche transit time (MITATT) diode is reported. This method can be applied to MITATT diodes with arbitrary doping distribution and arbitrary material combinations. The method is capable of estimating the mean-square value of the noise voltage as well as the noise distribution due to individual space steps caused by the individual noise sources. The method has been applied to a variety of Si double-drift diode structures with different levels of tunneling currents. The results indicate some new and interesting features of noise for mixed-mode operation.

A New mm-Wave GaAs~Ga0.52In0.48P Heterojunction IMPATT Diode

Abstract The potentials of a new lattice-matched material combination, GaAs~Ga0.52In0.48P, is explored using a computer simulation method for application as an IMPact ionization Avalanche Transit Time diode at mm-wave frequencies. It is observed that by suitably adjusting the ternary layer width in the drift region of the diode not only is the power output enhanced from 0.38W to 0.50W but also the noise measure reduces from 26 dB to 21 dB.

Simulation studies on the noise behaviour of double avalanche region diodes

Computer simulation studies on the noise behaviour of several Si-based double avalanche region (DAR) diodes, each having two avalanche regions separated by a common drift region, are presented. Our results indicate that with a suitable choice of operating frequency, close to the design frequency, a DAR diode produces less noise as compared to a double drift region or single avalanche region diode. Further, it is interesting to note from our results that out of the several structures considered, the DAR structure having only a π-type of drift region shows the lowest noise-to-power ratio at a frequency of 115 GHz.

Design optimization of a single-sided Si/SiGe heterostructure mixed tunnelling avalanche transit time double drift region

The potential of an Si/SiGe heterostructure mixed tunnelling avalanche transit time double drift region (DDR) with an SiGe layer on the p side alone is investigated. Our results indicate that this newly proposed structure has better mm wave properties and lower noise than the Si homostructure diode and Si/SiGe heterostructure diode with an SiGe layer on both n and p sides. Further, our results show that the diode properties are optimized for a particular width of the SiGe layer in the single-sided Si/SiGe heterostructure DDR.

Study of Si/SiGe Heterostructure DAR IMPATTs for Operation at 94 GHz

Computer simulation study of Si/Si0.5Ge0.5 heterostructure Double Avalanche Region (DAR) IMPact Avalanche Transit Time (IMPATT) diodes has been carried out using some computer simulation programs developed by us. The results show that by incorporating a 60 nm of SiGe layer on the n-side avalanche zone of the DAR diode, significant improvement in the mm-wave properties as well as noise measure of the diode is achieved. A noise measure of 7.8 dB at 94 GHz from this Si/SiGe DAR diode is note worthy

Phase Distortion Assisted MITATT Design for Compensation of Performance Deterioration due to Tunnel Current

A method for design of high frequency IMPATT, operating in MITATT mode is presented which can compensate for the deterioration in device performance due to loss of carrier build up phase delay caused by tunneling current. The results for 94 GHz Si DDR indicate that the device performance of MITATT diodes would be improved considerably with the modulation of diode design parameters based on phase distortion. The suggested method would provide a realistic approach for design consideration of any form of high frequency IMPATTs operating in mixed tunneling and avalanche mode.