Hide menu
spacing

Theoretical Physics

spacing

The research in the Theoretical Physics group is primarily focused on condensed matter physics/theoretical materials science, nanoscience and electromagnetic modeling.

The group also gives a large number of courses on graduate as well as undergraduate levels.

spacing

Highlights

spacing

___________________________________________________________________________

spacing

A silicon carbide room-temperature single-photon source

spacing

S. Castelletto , B. C. Johnson , V. Ivády , N. Stavrias , T. Umeda , A. Gali   and T. Ohshima

NATURE MATERIALS | VOL 13 | FEBRUARY 2014

DOI: 10.1038/NMAT3806

Searching for point defects in wide band gap semiconductors for quantum information, computation and photonic application is a rapidly broadening field of nowadays physics. Most of the pioneer works based on the spatial features of the negatively charged nitrogen vacancy center in diamond. However, the extreme properties of the host crystalline hinder the further improvement and realization of solid state devices for quantum control. Due to the versatility and the well-established growth and device engineering protocols of the silicon carbide (SiC), this material has become a potential candidate for suitable host for quantum applications.
In this joint experimental and theoretical paper, a stable and extreme bright (2×106 counts/s) singe photon emitter point defect was reported in SiC, which efficiently emit light at around 2.0 eV at room temperature. This result is a new and exciting development for the emerging SiC material system for future integrated quantum photonics devices. This source was assigned to the carbon antisite-vacancy pair based on ensemble measurements at low temperature showing the characteristic AB ZPLs. In the theoretical part of the paper we present the results of the first principles calculations that reveal the detailed electronic structure of the carbon antisite-vacancy pair (CSiVC) defect and provides reliable working model of the observed single photon emitter for the group theory consideration.

spacing

spacing

Figure caption:
Confocal microscopy images and spectra of single photon sources in 4H SiC. Confocal map of the low electron fluence sample excited with 660 nm (a) and 532 nm (b) lasers. The diffraction limited spots all correspond to single photon emitters. Map (a) has been scanned using a 10 nm FWHM 694 nm filter. Note the difference in color scale. c, Histogram of the number of centers observed as a function of the spatial FWHM measured and counted from (a,b). The histogram from a confocal map of an unprocessed sample is also shown indicating a clear increase in the defect density after irradiation and annealing at 300C. d, Normalized room temperature PL of a single photon source in the irradiated sample excited with 532 nm (i) and 660 nm (ii,iii) lasers. The laser wavelengths are indicated by the dashed lines. d(iii), PL of a center which was not anti-bunching. The transverse and longitudinal optic Raman modes (TO, LO) are also indicated. e, The corresponding anti-bunching curves for d(i) and (ii).

spacing

 

spacing

 

spacing

Responsible for this page: Fei Wang

Last updated:03/26/14