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.

Dislocation enhanced impurity diffusion

Abstract: Diffusion of silver in copper has been studied in the temperature range 485°c to 625°c using a new sectioning technique. The observed diffusion coefficients are all higher than would be expected from the extrapolation of existing high temperature data, and it has been assumed that this enhancement is due to dislocations providing easy paths for diffusion. The results are interpreted in this paper using the analysis of Hart (1957) as modified by Mortlock (1960) and yield the value 40 000±5000 cal/mole for the activation energy for the diffusion of silver atoms along dislocations in a copper lattice.

Observation of quantum Hall interferometer phase jumps due to a change in the number of bulk quasiparticles

Abstract: We measure the magneto-conductance through a micron-sized quantum dot hosting about 500 electrons in the quantum Hall regime. In the Coulomb blockade, when the island is weakly coupled to source and drain contacts, edge reconstruction at filling factors between one and two in the dot leads to the formation of two compressible regions tunnel coupled via an incompressible region of filling factor $\ u=1$. We interpret the resulting conductance pattern in terms of a phase diagram of stable charge in the two compressible regions. Increasing the coupling of the dot to source and drain, we realize a Fabry-Perot quantum Hall interferometer, which shows an interference pattern strikingly similar to the phase diagram in the Coulomb blockade regime. We interpret this experimental finding using an empirical model adapted from the Coulomb blockaded to the interferometer case. The model allows us to relate the observed abrupt jumps of the Fabry-Perot interferometer phase to a change in the number of bulk quasiparticles. This opens up an avenue for the investigation of phase shifts due to (fractional) charge redistributions in future experiments on similar devices.

Shallow donor neutralization in CdTe:In by atomic hydrogen

Abstract: Passivation effects in In doped n-CdTe upon exposure to rf hydrogen plasma are studied by electrical and photoluminescence measurements and were found to be maximum at about 150°C. Depth profiling by capacitance-voltage measurements show passivation of approximately an order of magnitude at 150°C and 50% at 170°C. No visual surface damage is seen. Reverse bias annealing experiments show that atomic hydrogen drifts in a charged state in n-CdTe, with reactivation kinetics of the donors different from the other well studied semiconductors. Manifestation of the donor passivation in photoluminescence is seen by the reduction of the donor bound luminescence.

Scanning gate experiments: From strongly to weakly invasive probes

Abstract: An open resonator fabricated in a two-dimensional electron gas is used to explore the transition from strongly invasive scanning gate microscopy to the perturbative regime of weak tip-induced potentials. With the help of numerical simulations that faithfully reproduce the main experimental findings, we quantify the extent of the perturbative regime in which the tip-induced conductance change is unambiguously determined by properties of the unperturbed system. The correspondence between the experimental and numerical results is established by analyzing the characteristic length scale and the amplitude modulation of the conductance change. In the perturbative regime, the former is shown to assume a disorder-dependent maximum value, while the latter linearly increases with the strength of a weak tip potential.