Solid State Physics Laboratory

About: Solid State Physics Laboratory is a facility organization based out in Delhi, India. It is known for research contribution in the topics: Quantum dot & Dielectric. The organization has 1754 authors who have published 2597 publications receiving 50601 citations.

Temperature effects in silicon solar cells

Abstract: The temperature variation of the relative spectral response RSR, short circuit current Isc and open circuit voltage Voc is measured and the results are theoretically discussed. The RSR at wavelengths larger than the peak wavelengths always increases with temperature. The observed increase is found to agree with theory when temperature variation of the absorption coefficient of light and of Ln the carrier diffusion length in the base is taken into account properly. The temperature variation of short wavelength RSR depends on S, the surface recombination velocity and L p d , L p is the carrier diffusion length in the diffused layer and d is the junction depth. If S is small and L p d is large, the RSR is practically independent of temperature. On the other hand if S is large and/or L p d is small, the RSR decreases as the temperature increases. A new relation between Ln, d and the peak position of RSR is derived. The observed temperature shift in the peak position agrees well with that predicted by this relation. The temperature increase of Isc and decrease of Voc are different for AM0 and AM1 illuminations. The observed differences can be explained at least qualitatively on the basis of the results obtained in this paper.

Improved Raman Effect Studies on Boron Carbide (B4.3C)

Abstract: With a FT Raman spectrometer highly resolved and reliable Raman spectra of B4.3C were obtained largely refuting previous results of other authors. The symmetry selection rules of IR and Raman active phonons are proved to hold. The most prominent Raman doublet at 270/320 and that at 869/928 cm−1 are due to pentagonal pyramids of the icosahedra symmetrically vibrating relative to the end atoms of the three-atomic chain. The broad band at 1065 cm−1 is attributed to corresponding vibrations of pairs of pentagonal pyramids in adjacent icosahedra. The remaining Raman-active phonons, mainly attributed to intraicosahedral vibrations, are comparably weak. At higher photon energies the luminescence radiation due to electron transitions is essential.

Anisotropy and Suppression of Spin-Orbit Interaction in a GaAs Double Quantum Dot.

Abstract: The spin-flip tunneling rates are measured in GaAs-based double quantum dots by time-resolved charge detection. Such processes occur in the Pauli spin blockade regime with two electrons occupying the double quantum dot. Ways are presented for tuning the spin-flip tunneling rate, which on the one hand gives access to measuring the Rashba and Dresselhaus spin-orbit coefficients. On the other hand, they make it possible to turn on and off the effect of spin-orbit interaction with a high on/off ratio. The tuning is accomplished by choosing the alignment of the tunneling direction with respect to the crystallographic axes, as well as by choosing the orientation of the external magnetic field with respect to the spin-orbit magnetic field. Spin lifetimes of 10 s are achieved at a tunneling rate close to 1 kHz.