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.

Design and fabrication of an innovative three-axis Hall sensor

Abstract: The measurement of all three components of a magnetic field, simultaneously to high precision with Hall sensors, remains a challenge. Given the high precision of state-of-the-art conventional uniaxial Hall sensors, this is disappointing. Currently, three-axis Hall sensors suffer from either, or a combination, of the following: large spatial distribution between active areas; high signal noise; cross-sensitivity between measurement axes due to angular errors or the planar Hall effect; the inability to measure at a single point in space and time. A new type of three-axis Hall sensor is proposed, consisting of three sets of uniaxial Hall sensors in a small active volume. The feasibility of the proposed sensor has been proven in a prototype with an active volume as small as 200 μm × 200 μm × 200 μm. Due to its unique configuration, the new sensor addresses current three-axis Hall sensor limitations: it provides a high spatial resolution of 30 μm × 30 μm × 1 μm for each field component; full field vector measurements practically at a single point in space and time; and a reduction of the planar Hall effect by a factor of 35. Angular errors between the individual Hall sensors in the prototype lie between 0.1° and 0.5°, above the tolerable error for non-corrected measurements. However, once understood they can be taken into account. With proper calibration, this type of three-axis Hall sensor has great potential for high-accuracy three-axis magnetic field measurements and is particularly suitable for field mapping of magnets.

Theory of photo induced open circuit voltage decay in a solar cell

Abstract: Experimental results of photo induced open circuit voltage decay in a solar cell are now available [1]. Theoretical expressions for the decay of the voltage are derived and used to interpret these experiments.

Fluorescent silk cocoon creating fluorescent diatom using a “Water glass-fluorophore ferry”

Abstract: Fluorophores are ubiquitous in nature. Naturally occurring fluorophores are exceptionally stable and have high quantum yield. Several natural systems have acquired fluorescent signature due to the presence of these fluorophores. Systematic attempt to harvest these fluorophores from natural systems could reap rich commercial benefit to bio-imaging industry. Silk cocoon biomaterial is one such example of natural system, which has acquired a fluorescent signature. The objective of this study is to develop simple, rapid, commercially viable technique to isolate silk cocoon membrane fluorophores and exploring the possibility of using them as fluorescent dye in bio-imaging. Here, we report an innovative water glass (Na2SiO3) based strategy to isolate the silk cocoon fluorophores. Isolated fluorophore is majorly quercetin derivatives and exhibited remarkable photo- and heat stability. Fluorescence and mass spectrometric analysis confirmed presence of a quercetin derivative. We further used this fluorophore to successfully label the silicate shell of diatom species Nitzschia palea.

Theoretical investigation of stark effect on shallow donor binding energy in InGaN spherical QD-QW

Abstract: In this paper, a simultaneous study of electric field and impurity's position effects on the ground-state shallow-donor binding energy in GaN│InGaN│GaN spherical quantum dot-quantum well (SQD-QW) as a function of the ratio of the inner and the outer radius is reported. The calculations are investigated using variational approach within the framework of the effective-mass approximation. The numerical results show that: (i) the binding energy is strongly affected by the external electric field and the SQD-QW dimension, (ii) a critical value of spherical system's radius is obtained constituting the limit of three dimension confinement and spherical thin layer confinement and (iii) the Stark shift increases with increasing electric field and it is more pronounced around the position of the impurity corresponding to the binding energy maxima than in the spherical layer extremities.