Showing papers by "Mukul K. Das published in 2021"
TL;DR: In this paper, the authors have reviewed the prospects of aluminium oxide (Al2O3) as surface passivation material and associated process technologies are also addressed, including negative fixed charges, high process stability and process feasibility to use it in ultrathin films.
Abstract: Surface recombination loss limits the efficiency of crystalline silicon (c-Si) solar cell and effective passivation is inevitable in order to reduce the recombination loss. In this article, we have reviewed the prospects of aluminium oxide (Al2O3) as surface passivation material and associated process technologies are also addressed. Its underlined negative fixed charges, high process stability and process feasibility to use it in ultrathin films, make it exciting one as surface passivation material. Other materials used for passivation and their limitations are addressed. Relevant deposition techniques and their aspects are also discussed here. Ultrathin Al2O3 is generally produced by conventional Atomic Layer Deposition (ALD) methods. But slow deposition rate and low throughput made the ALD process limited its application in commercial solar industry. Plasma Enhanced Chemical Vapour Deposition (PECVD) is also used as alternative one but it suffers from high temperature process stability. Al2O3 deposited by Radio Frequency (RF) sputtering is found out to be one of the best deposition techniques because of its low cost and higher deposition rate.
8 citations
TL;DR: In this paper, a theoretical model for n-p-n mid-infrared transistor lasers with a strain-balanced Ge0.85Sn0.15 multiple quantum well (MQW) structure in their base was developed.
Abstract: A theoretical model is developed for n–p–n mid-infrared transistor lasers (TLs) with a strain-balanced Ge0.85Sn0.15 multiple quantum well (MQW) structure in their base. The variation of the optical confinement factor, the modal gain, and the threshold current density is rigorously investigated for different numbers (N) of QWs in the MQW structure. The results show that overall the optical confinement factor and the modal gain increase with N. The frequency response of the MQWTL in the common-base (CB) configuration is estimated from the small-signal relationship between the photon density and the emitter current density by solving the laser rate equation and the continuity equation, considering the virtual states as a conversion mechanism. Increasing N causes the modulation bandwidth first to increase then to decrease with N. This reveals a shift in the nature of the device for higher values of N. The results also suggest that judicious selection of N will enable the proposed device to become a viable monolithic light source.
2 citations
TL;DR: In this article, a simple transport model is developed using the rate and continuity equation for the analysis of transient response of a multiple quantum well infrared photodetector, where the effect of carrier capture and the doping dependent optical absorption are incorporated in the model for accurate estimation of responsivity in the frequency domain.
Abstract: In this paper, a simple transport model is developed using the rate and continuity equation for the analysis of transient response of a multiple quantum well infrared photodetector. The effect of carrier capture and the doping dependent optical absorption are incorporated in the model for accurate estimation of responsivity in the frequency domain. In case of high capture time, 3 dB bandwidth swings 5 GHz for M = 10 by changing doping from 1.2 × 1017 cm−3 to 1 × 1018 cm−3 whereas it swings only 0.9 GHz for M = 52. Moreover, barrier width and QW periods on the transient responsivity and bandwidth of the detector has been examined and the results have been found out to be of great significance. However, responsivity variation with QW periods bears very less significance for LB > 48 nm. The role of capture time (1 ps–11 ps) on the 3 dB bandwidth has also been studied and the result shows a significant drop from 95 to 76 GHz for M = 20.
2 citations
TL;DR: In this article, an e-beam technique was used to grow a thin film Snox layer under different oxygen pressure and grain size, which has a significant effect on its surface morphology.
1 citations
01 Jan 2021
TL;DR: In this article, the authors developed a theoretical model for the Ge-Si0.15/Si 0.16 n-p-n mid-infrared transistor laser (TL) with strain-balanced Ge0.85Sn0.12Ge0.73Sn 0.15 multiple quantum well (QW) in the base and calculated the variation of optical confinement factor and modal gain for different number of QWs.
Abstract: In this work, a theoretical model developed for the Ge-Si0.12Ge0.73Sn0.15/Si0.11Ge0.73Sn0.16 n-p-n mid-infrared transistor laser (TL) with strain-balanced Ge0.85Sn0.15 multiple quantum well (QW) in the base. The variation of optical confinement factor and modal gain for different number of QWs is also calculated. The result shows that overall optical confinement factor and modal gain increase with the number of QW.