Atomic pseudopotentials for orthorhombic IV–VI compounds

The reflectance spectra of orthorhombic GeSe crystals are studied in the region 0.5 to 12 eV in polarized light with E 11 a and E (1 b a t 290 K and a Kramers-Kronig analysis is performed. The thermoreflectance spectra are investigated in the region 1 to 5 eV for E 11 a and E 11 b a t 300 and 90K. The energy band structure calculations of GeSe are carried out by the pseudopotential method, and the spectra of t.he imaginary part of the dielectric constant are calculated by the k * p method. A classification and interpretation of main structures of optical spectra of GeSe by direct interband transitions a t critical points I', U, T and high symmetry lines B' V, A is presented on the basis of calculated band structure and selection rules for optical dipole transitions of orthorhombic A4B6 crystals. I/ZCcJIenOBaHbI CneKTpbI OTPaHEeHHfl OpTOpOM6H~IeCKOrO HpHCTanna GeSe B CneKTpNIb€IO# o 6 n a c~~ OT 0,5 A 0 12 ev B nOJIflpH30BaHHOM CBeTC C E I] a A E I] b npPi TeMnepaTypC! 290 K A nposeneH ~H~J I A~ HpaMepca-Kpomira. kI3yqe~b1 cnewpbr TepMooTpameHufl B AHTepsane OT 1 no 5 eV nns non~pn3a1@ E 11 a A E 11 b n p~ 300 EI 90 K. nposeHeHbI paClieTb1 30HHOfi CTPYKTYPbI &Se MeTOnOM IICeBAOnOTeHqHana H CneKTpOB MHHMOfi gaCTH AH3JIeKTPAYeCKOfi IIPOHH4aeMOCTki k * P-MeTOllOM. Ha OCHOBe PaCCWITaHHOfi ~O H H O~~ CTPYKTYPH H npamn o~6opa n n~ nnnonbHbIx OnTmecwix nepexonoB B OPTO-P O M~M V~C K H X HpHcTannax A4B6 nposeneHa xnaccH@Kaqax H AHTepnpeTaqufl OCHOBHHS CTPYKTJ'P OIITHqeCKAX CneKTpOB GeSe IlpIIMbIMH MeHU(y3OHHbIMH nepeXO&3MH B KPATII-qeCKHX TOqKaX r, u H T, a TaKHEe Ha JIHHHIIX BbICOKOfi CAMMeTpAA B', v H A.

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“…The form factmrs of Ge and Se pseudopotentials were taken from [21]. The calculations were carried out using 270 plane waves.…”

Section: Energy Band Structure Calculatioiismentioning

confidence: 99%

Reflectance and thermoreflectance spectra and energy band structure of GeSe crystals

Valiukonis

Gashimzade

Guseinova

et al. 1983

Physica Status Solidi (b)

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“…Because of the low symmetry (space group DBt) the energy band structure of the layer-type AIVBV1 compounds is rather complicated, especially in the vicinity of the absolute extrema, as was shown by theoretical calculations 13 t o 81 and optical investigations [9 t o 161. However, from theoretical calculations it follows that the relative location of the absolute extrema of energy bands is very sensitive t o the pseudopotential parameters [5] and needs an experimental correction.…”

Section: Introductionmentioning

confidence: 99%

“…Experimental data are compared with the calculated energy band structure of GeS [3], GeSe [6], and SnSe [5,7,15].…”

Section: Introductionmentioning

confidence: 99%

Optical spectra and energy band structure of layer‐type A^IVB^VI compounds

Valiukonis

Guseinova

Keivaitb

et al. 1986

Physica Status Solidi (b)

133

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The electroreflectance and absorption spectra as well as the hydrostatic pressure dependence of the fundamental absorption edge of GeS, GeSe, SnS, and SnSe crystals are investigated in polarized light. The lowest direct energy gaps are found to be 1V1— 1V1 (E | | a) and 1Λ4— 1Λ4 (E || b) for Ge and Sn monochalcogenides, respectively. The pressure coefficient of the energy gap 1Λ4— 1Λ4 dE/AP = = — (1.3 ± 0.1) × 10−4 eV/MPa of SnSe and SnS is almost twice larger than that of the gap 1V1— 1V1 in GeSe, GeS, and SnSe. On the basis of these investigations, different absorption mechanisms responsible for the fundamental absorption edge are discussed.

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“…3) and selection rules for optical dipole transition [l2I3) the optical structures Eb (1.05 eV) and E , (1.24 eV) in modulation spectra ( Fig. 1 and 2 [17] to the experimental one.…”

Section: Discussionmentioning

confidence: 95%

Electroreflectance and Thermoreflectance Spectra of SnSe Crystals

Valiukonis

Gashimzade

Guseinova

et al. 1984

Physica Status Solidi (b)

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The electroreflectance and thermoreflectance spectra of SnSe crystals are investigated in polarized light with E 11 u and E 11 b. The direct energy gaps are 1.05 and 1.24 eV for light polarizations E I I b and E I I a, respectively. The polarization anisotropy of modulation spectra of SnSe is strong near the gap and becomes weak at higher energies. The structures of investigated spectra in the vicinity of the forbidden energy gap are interpreted by direct optical transitions on the high symmetry line A-I?-V in the calculated energy band structure.

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Atomic pseudopotentials for orthorhombic IV–VI compounds

Cited by 19 publications

References 13 publications

Reflectance and thermoreflectance spectra and energy band structure of GeSe crystals

Reflectance and thermoreflectance spectra and energy band structure of GeSe crystals

Optical spectra and energy band structure of layer‐type A^IVB^VI compounds

Electroreflectance and Thermoreflectance Spectra of SnSe Crystals

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Atomic pseudopotentials for orthorhombic IV–VI compounds

Cited by 19 publications

References 13 publications

Reflectance and thermoreflectance spectra and energy band structure of GeSe crystals

Reflectance and thermoreflectance spectra and energy band structure of GeSe crystals

Optical spectra and energy band structure of layer‐type AIVBVI compounds

Electroreflectance and Thermoreflectance Spectra of SnSe Crystals

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Optical spectra and energy band structure of layer‐type A^IVB^VI compounds