Investigation of the Light Absorption Mechanisms near Exciton Resonance in Layered Crystals

✍ Scribed by Yu.I. Zhirko

• Publisher: John Wiley and Sons
• Year: 2000
• Tongue: English
• Weight: 193 KB
• Volume: 219
• Category: Article
• ISSN: 0370-1972
• DOI: 10.1002/1521-3951(200005)219:1<47::aid-pssb47>3.0.co;2-q

✦ Synopsis

Wide temperature range (4.5 to 300 K) exciton absorption spectra of pure, doped and GaSe crystals intercalated by manganese have been studied. It has been shown that at low temperatures in p-type GaSe crystals the degeneration in the momentum space of the n = 1 exciton band with holes localized in quantum wells leads to suppression of the exciton oscillator strength f exc . The slight doping (0.1 wt%) of GaSe by Mn impurities compensates holes and restores the polariton light absorption mechanism. The oscillator strength of the exciton and band-to-band optical transitions f exc = f cv = 0.05, plasma frequency w p = 2.9 Â 10 14 s ± ±1 , and value of longitudinal-transversal splitting D L-T = 0.4 cm ± ±1 of polariton branches have been found for GaSe crystals. It is assumed that a slight excess of f exc over f cv in intercalated GaSe crystals occurred due to the participation of the ªindirect phototransitionº mechanism in the light absorption when the excitons undergo an additional scattering on local interlayer optical vibrations.