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.

Transport properties of clean quantum point contacts

Abstract: Quantum point contacts are fundamental building blocks for mesoscopic transport experiments and play an important role in recent interference and fractional quantum Hall experiments. However, it is unclear how electron?electron interactions and the random disorder potential influence the confinement potential and give rise to phenomena such as the mysterious 0.7 anomaly. Novel growth techniques of AlXGa1?XAs heterostructures for high-mobility two-dimensional electron gases enable us to investigate quantum point contacts with a strongly suppressed disorder potential. These clean quantum point contacts indeed show transport features that are obscured by disorder in standard samples. From these transport data, we are able to extract those parameters of the confinement potential that describe its shape in the longitudinal and transverse directions. Knowing the shape (and hence the slope) of the confinement potential might be crucial for predicting which interaction-induced states can best form in quantum point contacts.

HgCdTe avalanche photodiodes: A review

Abstract: This paper presents a comprehensive review of fundamental issues, device architectures, technology development and applications of HgCdTe based avalanche photodiodes (APD). High gain, above 5×103, a low excess noise factor close to unity, THz gain-bandwidth product, and fast response in the range of pico-seconds has been achieved by electron-initiated avalanche multiplication for SWIR, MWIR, and LWIR detector applications involving low optical signals. Detector arrays with good element-to-element uniformity have been fabricated paving the way for fabrication of HgCdTe-APD FPAs.

Stability of spin states in quantum dots

Abstract: We have investigated electronic transport through a Coulomb-blockaded quantum dot in which interactions are strong. Linear changes in conductance peak spacings with in-plane magnetic field are observed and interpreted in terms of Zeeman splitting of single-particle levels. Thereby, the measurements allow tracking changes in the dot's ground-state spin as the dot is gradually opened to the leads and the electron number is changed. Spin states have been identified in the weak- $(kTg\ensuremath{\Gamma}),$ intermediate- $(\ensuremath{\Gamma}\ensuremath{\approx}kT),$ and strong- $(\ensuremath{\Gamma}gkT)$ coupling regime. It is found that ground states with spin $S=0$ or $S=1/2$ are most likely, while larger total spins $Sg~1$ can occasionally occur, despite the large number of 50--100 electrons. A g factor close to the bare bulk GaAs value has been determined experimentally for the majority of the spin states. A perpendicular magnetic field applied to the dot in the same state allows the investigation of spin-pair candidates under conditions where orbital effects dominate the evolution of conductance peaks. Strong correlations in the position and in the amplitude of neighboring peaks allow the final identification of spin pairs. The method of combining parallel and perpendicular magnetic fields for identifying spin states and spin-pairs works well for intermediate and strong coupling of dot states to the leads while the data in the weak-coupling regime is less conclusive. Our results indicate that the spin degree of freedom is remarkably stable and the spin states are well described within a single-particle picture.