Gopa Sen

Modeling of tunneling current density of GeC based double barrier multiple quantum well resonant tunneling diode

The double barrier quantum well (DBQW) resonant tunneling diode (RTD) structure made of SiGeSn/GeC/SiGeSn alloys grown on Ge substrate is analyzed. The tensile strained Ge1−zCz on Si1−x−yGexSny heterostructure provides a direct band gap type I configuration. The transmission coefficient and tunneling current density have been calculated considering single and multiple quantum wells. A comparative study of tunnelling current of the proposed structure is done with the existing RTD structure based on GeSn/SiGeSn DBH. A higher value of the current density for the proposed structure has been obtained.

Prediction of band offsets of the ternary alloy Si 1-x-y Sn x C y on Si

The band offsets and band gap for strained Si<inf>1-x-y</inf>Sn<inf>x</inf>C<inf>y</inf> layers grown on Si substrate are estimated. The hydrostatic strain, the uniaxial strain and the intrinsic alloy effect are considered separately. The model is verified with the available bandgap energy of binary material.

IN VITRO EFFECT OF HORMONES ON THE BARK OF PLUMERIA RUBRA LINN. VAR. ACTUIFOLIA BAILEY

Young bark (with cambium) of Plumeria rubra Linn. var. acutifolia Bailey was cultured in solid media (i) without hormone, (ii) Kinetin (K), (iii) with GA3 and (iv) with IAA at concentrations of 0.05, 0.10, 0.15 and 0.20 mg per litre. The nutrients of the media were fed laterally through the cambium zone. The amount of the phloem zone was increased considerably by GA3, less by K and IAA. The lignified secondary wall of the pericyclic living fibres was dissolved by each of the hormones. Sieve tube member length decreased in all treatments, more in higher concentrations. K decreased the frequency of sieve tubes (most at 0.10 mg/α) and increased the frequency of parenchyma cells (optimum at 0.10 mg/α). GA3 also favoured formation of parenchyma cells and decrease of the frequency of sieve tubes, progressively with the increase of concentration. IAA also increased the parenchyma cell frequency progressively with concentration and decreased slightly the sieve tube frequency. IAA and GA3 increased ray frequency and decreased parenchyma cell diameter, much at high concentration. But K had less effect on ray frequency and increased parenchyma cell diameter progressively with concentrations.