Polariton emission from CuGaSe2 crystals

Exciton spectra and energy band structure of CuGaSe2single crystals

“…CuGaSe 2 single crystals were grown by iodine vapour transport in closed quartz ampoules and presented 0.3-0.4 mm thick plates with the mirror-like surfaces of 2.5 × 1.0 cm 2 sizes. Surfaces of some plates contain the c-axis [12]. The reflectivity measurements were performed at 77 K using a Specord M40 while exciton reflectivity and luminescence spectra were measured at 10 K, using a double DFS-32 spectrometer with 5 Å mm −1 dispersion.…”

“…Equation ( 3) was successfully used to simulate the reflectivity contours and to determine the exciton parameters of II-VI and I-III-VI compounds [12].…”

“…The CuGaSe 2 (CGS) belongs to the I-III-VI type of compounds that crystallizes in the chalcopyrite structure with the space group I 42d − D 12 2d . This type of material is being intensively investigated and considered of great interest for applications in photovoltaics and optoelectronics [1,2].…”

“…Devices based on CuGa 1−x In x Se 2 have demonstrated efficiencies up to 19.3% [3]. Some optical and transport measurements were carried out on CuGaSe 2 thin films and single crystals [4][5][6][7][8][9][10][11][12][13] and values of the fundamental gap and its temperature dependence, the crystal field and spin-orbit valence band splitting as well as phonon and exciton parameters and possible defect level schema were reported. The energy band structure of I-III-VI compounds has been calculated as the nearest zincblende analogue [14].…”

“…The excitonic spectra of CuGaSe 2 [10][11][12] as well as its energy band structure at energies higher than the fundamental band gap [5,10] are not yet well studied. Kramers-Kronig relations for analysis of the experimental data were not used and the electronic transitions observed up to present are 5 Author to whom any correspondence should be addressed.…”