Nikhil Ranjan Das

Bio: Nikhil Ranjan Das is an academic researcher from University of Calcutta. The author has contributed to research in topics: Photodetector & Quantum dot. The author has an hindex of 12, co-authored 132 publications receiving 489 citations. Previous affiliations of Nikhil Ranjan Das include McMaster University & Division of IT Convergence Engineering.

Calculating the photocurrent and transit-time-limited bandwidth of a heterostructure p-i-n photo-detector

Abstract: We have calculated the photocurrent and transit-time-limited bandwidth of a heterostructure p-i-n photodetector. The effective heights of potential barriers at the heterojunction interfaces in the valence band and conduction band have been calculated at different bias voltage and grading lengths for InP-In/sub 0.53/Ga/sub 0.47/As and Al/sub 0.2/Ga/sub 0.8/As-GaAs systems. The rates of thermionic emission from the trap can then be easily estimated for each type of material system at an applied bias and for a particular thickness of the grading layer. An expression for current through the photodetector in the presence of traps has been derived by solving rate equations for an arbitrary distribution of photogenerated carriers in the absorption region. Frequency-domain calculations are used to find the transit-time-limited 3-dB bandwidths of the photodetector. It has also been indicated how the results could be used to estimate the bandwidth of the photodetector without performing the exact calculations in the presence of interface trapping. The results from the present model show good agreement with experimental data already reported in the literature for conventional and resonant-cavity-enhanced p-i-n photodetectors.

Intrinsic plasticity of silicon nanowire neurotransistors for dynamic memory and learning functions

Abstract: Neuromorphic architectures merge learning and memory functions within a single unit cell and in a neuron-like fashion. Research in the field has been mainly focused on the plasticity of artificial synapses. However, the intrinsic plasticity of the neuronal membrane is also important in the implementation of neuromorphic information processing. Here we report a neurotransistor made from a silicon nanowire transistor coated by an ion-doped sol–gel silicate film that can emulate the intrinsic plasticity of the neuronal membrane. The neurotransistors are manufactured using a conventional complementary metal–oxide–semiconductor process on an 8-inch (200 mm) silicon-on-insulator wafer. Mobile ions allow the film to act as a pseudo-gate that generates memory and allows the neurotransistor to display plasticity. We show that multiple pulsed input signals of the neurotransistor are non-linearly processed by sigmoidal transformation into the output current, which resembles the functioning of a neuronal membrane. The output response is governed by the input signal history, which is stored as ionic states within the silicate film, and thereby provides the neurotransistor with learning capabilities. A neurotransistor made from a silicon nanowire transistor coated by an ion-doped sol–gel silicate film can emulate the intrinsic plasticity of the neuronal membrane.

Study of Component Crosstalk and Obtaining Optimum Detection Threshold for Minimum Bit-Error-Rate in a WDM Receiver

Abstract: In this paper, bit error rate and power penalty in a WDM receiver system in the presence of component crosstalk with finite interferers are studied using a simplified analysis and some optimum detection thresholds are suggested for minimum bit error rate. Error probabilities are calculated considering a unipolar bit stream of optical signals at the receiver input. Probability density function in the presence of crosstalk deviates from conventional Gaussian function. Effects of receiver noise, number of interfering channels and crosstalk levels on the receiver performance are shown. Optimum detection thresholds for minimum bit error rates in the WDM receiver in presence of component crosstalk are investigated and summarized in tabular form.

The European Physical Journal D

Abstract: EPJ E publishes papers describing advances in the understanding of physical aspects of Soft Matter and Biological Systems. The journal includes reports of experimental, computational and theoretical studies and appeals to the broad interdisciplinary communities including physics, chemistry, biology, mathematics and materials science. Unique features of EPJ E: Tips and tricks short papers focused on a novel methodological approach that enables new science Colloquia papers reviewing new directions in Research Prestigious international board of editors Highly competent and fast editorial handling Global contributions and global readership Commonly used title abbreviations: Eur. Phys. J. E, Eur.Phys.J.E, EPJE, EPJ E