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Numerical analysis of SiGeSn/GeSn interband quantum well infrared photodetector

Pareek P., Das M. K., Kumar S.

Opto-Electronics Review

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2018

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Vol. 26, No. 2

149--157

EN

In this paper, detailed theoretical investigation on the frequency response and responsivity of a strain bal-anced SiGeSn/GeSn quantum well infrared photodetector (QWIP) is made. Rate equation and continuity equation in the well are solved simultaneously to obtain photo generated current. Quantum mechanical carrier transport like carrier capture in QW, escape of carrier from the well due to thermionic emission and tunneling are considered in this calculation. Impact of Sn composition in the GeSn well on the frequency response, bandwidth and responsivity are studied. Results show that Sn concentration in the GeSn active layer and applied bias have important role on the performance of the device. Significant bandwidth is obtained at low reverse bias voltage, e.g., 200 GHz is obtained at 0.28 V bias for a single Ge0.83 Sn0.17 layer. Whereas, the maximum responsivity is of 8.6 mA/W at 0.5 V bias for the same structure. However, this can be enhanced by using MQW structure.

2

Influence of doping on the performance of GaAs/AlGaAs QWIP for long wavelength applications

Billaha A., Das M. K.

Opto-Electronics Review

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2016

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Vol. 24, No. 1

25--33

EN

Effect of doping and other device parameters on inter sub−band transition in the well, responsivity and dark current of GaAs/AlxGa1-xAs quantum well infrared photodetector (QWIP) is investigated using theoretical model. 2X2 Hamiltonian method is used to calculate Eigen energy states in this modelling. Results show that peak absorption, responsivity and spectral broadening width increase nonlinearly with increasing doping concentration in the well. Peak absorption coefficient increases with increase in well width also. Moreover, with increase in mole fraction of Al in AlxGa1-xAs barrier, the inter sub-band absorption is enhanced but, peak wavelength of absorption shifts towards shorter wavelengths. Dark current density depends on both, the doping concentration and applied bias.

3

Non-dominated Rank based Sorting Genetic Algorithms

Ghosh A., Das M.K.

Fundamenta Informaticae

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2008

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Vol. 83, nr 3

231-252

EN

In this paper a new concept of ranking among the solutions of the same front, along with elite preservation mechanism and ensuring diversity through the nearest neighbor method is proposed for multi-objective genetic algorithms. This algorithm is applied on a set of benchmark multi-objective test problems and the results are compared with that of NSGA-II (a similar algorithm). The proposed algorithm is seen to over perform the existing algorithm. More specifically, the new approach has been used to solve the deceptive multi-objective optimization problems in a better way.