P. R. Tripathy

Bio: P. R. Tripathy is an academic researcher from Purushottam Institute of Engineering & Technology. The author has contributed to research in topics: Diode & IMPATT diode. The author has an hindex of 2, co-authored 4 publications receiving 14 citations.

Possible Realization of Near Optimum Efficiency from n-Si-Ge/p-Ge-Si DDR Hetero Structure IMPATT Diode

Abstract: Avalanche breakdown in a p-n junction can generate rf negative resistance due to twin delay mechanism (Avalanche Delay associated with growth of charge bump and transit time delay caused due to time elapsed for the grown charge bump drifting through the depletion zone) leading to generation of high frequency power in IMPATT mode. With the advancement of device technology and with the motive of furtherance of device performance, replacement of homo junction of single elemental semiconductor with hetero junction, hetero structure junctions from lattice matched pair of elemental semiconductors is now being explored as supported by recent reports. The introduction of an n-Ge and p-Ge impurity bumps on either side of junction interface of a Si p-n junction, results in the formation of a n-Si-Ge/p-Ge-Si hetero structure p-n junction. The analysis of such hetero structure Impatt diode for generation of micro/mm-wave power at designed atmospheric window frequencies of 15 and 94 GHz becomes the scope of the study of this paper. The results are computed through three tier sophisticated computer algorithm indicate efficiency enhancement in case of proposed hetero structure to nearly 29% (at X-band) as against only 14% for the corresponding the homo junction diodes associated with increase of diode negative conductance by nearly two fold which in turn could enhance the rf power delivery from the hetero structure diode by many fold. Presence of low BG Ge near high field junction interface and its order high carrier ionization rate (compared to Si) localizes the avalanche zone to below 10% of the depletion zone and thereby pushes the device efficiency and value of negative conductance. However the performance of complementary n-Ge-Si/p-Si-Ge hetero structure remains close to Si or Ge homo junction. The results are highly encouraging which may make Si-Ge-Si Hetero Structure Diode as a prospective microwave generator.

Possible realization of near optimum efficiency from n-Si-Ge/p-Ge-Si DDR Hetero Structure IMPATT Diode

Abstract: A p-n junction under reverse bias avalanche breakdown condition is capable of producing high frequency rf power in Impatt mode With the advancement of Device Technology, the present state of art reports realization of alloy Si-Ge junction, Si-Ge hetero junction Introduction of a n-Ge and p-Ge impurity bumps near the junction face on respective side of Si p-n junction leaves an asymmetrical hetero structure junction which has become the scope of study of this paper for operation at 15 and 96 GHz Three tier sophisticated computer algorithm has been framed and used for Impatt analysis of resulting n-Si-Ge/p-Ge-Si Hetero Structure reveals realization of device efficiency as high as 296% (Theoretical Optimum Efficiency of Impatt Diode=31%) and also high value of negative conductance Presence of Ge layer near junction and an order high carrier ionization rate in Ge compared to Si localizes the avalanche zone, which pushes the efficiency and RF power generation Similar results are also noticed for 96 GHz operations The performance from this structure is observed to be superior by considerable extent as compared to Si and Ge homo structure However the complementary hetero structure having the form n-Ge-Si/p-Si-Ge is observed to exhibit performance almost on par to Si and Ge homo structures The results are highly encouraging which may make Si-Ge Hetero Structure Diode as a microwave generator

MM-wave characteristics of SiC-based IMPATT oscillators

Abstract: Wide band gap semiconductor SiC with their superior electrical properties are likely candidates to replace conventional low band gap materials like Si and GaAs in the near future for RF power applications. The authors have therefore studied this prospects through advanced computer simulation experiment on hexagonal (both 4H and 6H) SiC based double drift region IMPATT diodes. The study indicates that around 300GHz, 4H-SiC based Impatt devices is capable of generating high microwave power with efficiency as compared to 6H-SiC based IMPATT diodes for the same frequency of operation.

GaN/AlGaN based complementary p + -p − -p-n + ATT-device for application in THz Imaging

Abstract: A detailed simulation investigation is carried out on the hetero-structure complimentary (p+-p−-p-n+) IMPATT oscillator for Terahertz power generation It is observed that this newly proposed GaN/AlGaN IMPATT may generate a pulsed power density of ∼8×1010 Wm−2 with an efficiency of 11%, whereas it's flatly doped counterpart is capable of delivering a pulsed power density of only 3×1010 Wm−2 with 7% efficiency The total parasitic series resistance, R S , including that due to the un-depleted region in device and also the effects of ohmic contact resistances, has been found to be a major problem that reduces the negative resistance significantly and thus it has a detrimental effect on THz oscillation of the device The study reveals that the value of R S decreases by 40% as the structure, semiconductor material pair as well as doping profile of the diode changes suitably from conventional to the proposed hetero-structure p+-p−-p-n+ type, by incorporating a 300A0 Al 04 Ga 06 N layer in the p-drift region This first study will be a useful guide in the THz-sector to meet the ever-increasing demand of semiconductor THz-sources for application in Imaging or in improvised explosive device (IED) detection

GaN/Al x Ga 1−x N/GaN heterostructure IMPATT diode for D-band applications

Abstract: In this paper, a novel structural impact ionization avalanche transit time (IMPATT) diode configured by GaN/AlxGa1−xN/GaN heterostructure is investigated at the operation frequency of D-Band. Simulation results show that, with Al composition x varies from 0.2 to 0.6, a more localized avalanche region width is obtained, the device breakdown voltage increases gradually, while the RF output power and the DC-to-RF conversion efficiency have also shown significant improvement as compared with the GaN homostructure IMPATT diode. The highest values of the RF output power density and the DC-to-RF conversion efficiency of GaN/Al0.4Ga0.6N/GaN heterostructure are obtained as 1.56 MW/cm2 and 21.99%, larger than that of 1.02 MW/cm2 and 16.37% for GaN homostructure IMPATT diode. Meanwhile, the lowest Q factor can be achieved, which implies that heterostructure IMPATT diodes exhibit better stability and higher growth rate of microwave oscillation compared with conventional IMPATT diodes.

Possible realization of near optimum efficiency from n-Si-Ge/p-Ge-Si DDR Hetero Structure IMPATT Diode

Abstract: A p-n junction under reverse bias avalanche breakdown condition is capable of producing high frequency rf power in Impatt mode With the advancement of Device Technology, the present state of art reports realization of alloy Si-Ge junction, Si-Ge hetero junction Introduction of a n-Ge and p-Ge impurity bumps near the junction face on respective side of Si p-n junction leaves an asymmetrical hetero structure junction which has become the scope of study of this paper for operation at 15 and 96 GHz Three tier sophisticated computer algorithm has been framed and used for Impatt analysis of resulting n-Si-Ge/p-Ge-Si Hetero Structure reveals realization of device efficiency as high as 296% (Theoretical Optimum Efficiency of Impatt Diode=31%) and also high value of negative conductance Presence of Ge layer near junction and an order high carrier ionization rate in Ge compared to Si localizes the avalanche zone, which pushes the efficiency and RF power generation Similar results are also noticed for 96 GHz operations The performance from this structure is observed to be superior by considerable extent as compared to Si and Ge homo structure However the complementary hetero structure having the form n-Ge-Si/p-Si-Ge is observed to exhibit performance almost on par to Si and Ge homo structures The results are highly encouraging which may make Si-Ge Hetero Structure Diode as a microwave generator

Dependence of Negative Resistivity on Current Density and Junction Temperature for DDR IMPATT

Abstract: Negative resistivity of Si and Si0.9Ge0.1 DDR IMPATT diode are numerically computed using double iterative method and modified Runge-Kutta method and results are compared for identical input parameters. Simulation is based on simultaneous solution of Poisson's equation, continuity equation and carrier diffusion equation in addition with the effect of mobile space charge subject to the appropriate boundary conditions at the edges of depletion layer. Effect of junction temperature and current density on resistance is evaluated for optimum performance in CE mode. Peaks of the resistivity profile depend on temperature, bias current and frequency of operation. Results suggest that Si0.9Ge0.1 shows more negative resistance than the conventional one, and thus it may be considered as the suitable alternative choice for microwave source.

A new model of heterostructure GaAs/Ge IMPATT diode at W-band frequency

Abstract: In this paper, a new heterostructure based on GaAs/Ge impact ionization avalanche transit time diode (IMPATT) is investigated at 94 GHz design frequency, with an emphasis on the optimized current density A complete theoretical simulation with validatation of experimental results found that this type of structure is possible for high efficiency near about 135 % as compared to Ge (13 %) and GaAs (11 %) homostructure devices But the rf power in case of GaAs is higher of about 788 mW as compared to other diodes because of due to high breakdown voltage The result shows that heterostructure based IMPATT diode gives high efficiency with moderate power The available experimental methods and the simulation results will be suitable for high efficiency diode used for communication

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.