Stimulated terahertz emission due to electronic Raman scattering in silicon

Stimulated Raman emission in the terahertz frequency range (4.8–5.1 THz and 5.9–6.5 THz) has been realized by optical excitation of arsenic donor centers in silicon at low temperatures. The Stokes shift of the observed laser emission is 5.42 THz which is equal to the Raman-active donor electronic transition between the ground 1s(A1) and the...

Evidence of noncascade intracenter electron relaxation in shallow donor centers in silicon

Noncascade relaxation of photoexcited electrons on ionized donor centers has been observed in silicon doped by arsenic (Si:As) at low temperatures. Emission spectra of the Si:As terahertz intracenter laser give evidence of specific channels for the electron relaxation through low-lying donor states. The dominating relaxation channels strongly...

Elucidation of homojunction formation in CuInS2 with impedance spectroscopy

Type transformation in CuInSe2 and CuInS2 solar cells is an important issue with far reaching consequences. In the present study, the presence of a p-n homojunction inside CuInS2 in a TiO2/CuInS2 device is revealed with a detailed impedance spectroscopy and capacitance study. A n-type CuInS2 film with a thickness of 40?nm is found at the TiO2 (n...

Location of lanthanide impurity levels in the III-V semiconductor GaN

Knowledge from lanthanide spectroscopy on wide band gap (6–10?eV) inorganic compounds is used to understand and predict optical and electronic properties of the lanthanides in the III-V semiconductor GaN. For the first time the location of the 4fn ground state energy of each divalent and trivalent lanthanide ion relative to the valence and...

Deep-level transient spectroscopy of TiO2/CuInS2 heterojunctions

Deep-level transient spectroscopy (DLTS) has been used to measure the concentration and energy position of deep electronic states in CuInS2. Flat TiO2?CuInS2 heterojunctions as well as TiO2-CuInS2 nanocomposites have been investigated. Subband-gap electronic states in CuInS2 films are mostly due to antisite point defects and vacancies....

Temperature dependent spectroscopic studies of the electron delocalization dynamics of excited Ce ions in the wide band gap insulator, Lu2SiO5

Electron delocalization processes of optically excited states of Ce3+ impurities in Lu2SiO5 were investigated by means of a temperature and spectrally resolved photoconductivity study. By monitoring separately the strength of the photocurrent resulting from excitation into each of the Ce3+?5d absorption bands, over a broad temperature region,...

Stimulated terahertz emission from group-V donors in silicon under intracenter photoexcitation

Frequency-tunable radiation from the free electron laser FELIX was used to excite neutral phosphorus and bismuth donors embedded in bulk monocrystalline silicon. Lasing at terahertz frequencies has been observed at liquid helium temperature while resonant pumping of odd parity impurity states. The threshold was about two orders of magnitude...