Optical properties of the quaternary alloy system Culn(SxSe1−x)2 investigated by spectroscopic ellipsometry

Abstract

Experimental results for the pseudodielectric function ͗⑀͘ of CuIn(S x Se 1Ϫx ) 2 alloy system are reported. The investigation has been performed on the full composition range using crystals cut from ingots of 10 mm diameter and 40 mm length. The ingots were grown using the classical Bridgman method. Ellipsometric measurements were performed at room temperature in the range 1.5-5.5 eV. The energies of critical points have been determined from the imaginary part of the dielectric function. The transition energies ͑E 1 , E 2 , E 3 , and E 4 ͒ are found to shift linearly to higher energies as the sulfur content increases. The copper d level is found to be dominant in the ranges 2.5-3.5 eV for CuInSe 2 and 2.8-4 eV for CuInS 2 .

Single crystal growth and characterization of copper aluminum indium disulfide chalcopyrites

“…4 1ðdÞ ÀE A , the energy location of the Cu nonbonding d orbital is about 1.817 eV below the E V top in CuInS 2 . The average energy value of the E 1 transitions in CuInS 2 at 300 K is in accordance with an E 1 peak measured by ellipsometry measurement [28]. The E E feature can be assigned as the interband transition from Cu d to G 1C .…”

“…The main valence band in the Cu(Al x In 1 À x )S 2 chalcopyrite series was constructed by Cu 3d-S 3p hybridizations. The incorporation of copper d orbital is the main difference between the band structures of a chalcopyrite and a zinc-blende crystal [28]. In the case the transition metal incorporated in the chalcopyrites, the d electrons will split into t-d M (d xy , d xz , d yz ) and e-d M (d z 2 , d x 2 Ày 2 ) manifolds when replacing either cation of the host in the zinc blendes.…”

“…The XPS spectrum of Cu(Al 0.5 In 0.5 )S 2 near the valence band ( À 22 to 0 eV) is also included for comparison. Previous theoretical calculation [27] and ellipsometry measurement [28] indicated that most of the critical-point transitions are occurred at G point. The lowest conduction band is at G 1C (p) by S 3p n .…”

A mild solvothermal route to chalcopyrite quaternary semiconductor CuIn(SexS1 − x)2 nanocrystallites

“…The CuIn(Se x S 12x ) 2 quaternary alloy system can be synthesized by a variety of ways such as solid state reaction at elevated temperature, 8 the Bridgman method, 9 electrodeposition, 10 spray pyrolysis, 11 sputtering, 12 coevaporation, 13 organometallic precursors, 14 chemical transport reaction, 15 chalcogen (S and Se) vapor diffusion into Cu-In alloy, 16 microwave irradiation, 17 and ionized cluster beam techniques. 18 However, these methods require either very high temperature (typically 600-900 ‡C), high pressure or special apparatus.…”

Studying the Optical and Electrical Properties of CuGa0.5In0.5Se2 Chalcopyrite Due to Substrate Temperature and Gamma Irradiation

“…Different techniques are performed to obtain films of chalcopyrite compounds; such as the Bridgman method, hightemperature solid-state reaction method, electrodeposition, spray pyrolysis, sputtering, co-evaporation, and organo-metallic precursors. [2][3][4][5][6][7][8][9] Copper indium di-selenide is considered the greatest absorber compound with a smaller thickness for solar radiation due to it is highly absorption coefficient (>10 5 cm À1 ) and direct optical band energy. [10][11][12] CuInSe 2 and CuIn x Ga 1Àx Se 2 chalcopyrite thin films have a high potential for terrestrial and space applications.…”