Multiplication of electronic excitations in CaO and YAlO₃crystals with free and self-trapped excitons

Abstract

Using synchrotron radiation of €-32 eV the reflection spectrum md excitation spectra for 5.7.4.6 and 2.8 eV emissions have been measured for a freshly cleaved CaO crystal at wCr.In CaO. indirect band-to-band m i t i o n s take place in the region of hv > 6.4 eV. The excitation spectra for intrinsic emissions of 5.9 and 4.2 eV were measured in a YAlO, crystal at LHCT a well. As in many other dielectiics the electron-hole mechanism of multiplication of electronic excitations connected with the creation of secondary electron-hole pain by hot photoelectrons also occurs in CaO and YA103 crysols. The creation ofsecondary excitons by hot photoelectrons has been detected in YAI03 for the Brst time. The excitonic mechanism of multiplication of electronic excitations has a high efficiency in crystals with self-trapping excitons of small radii.

Modeling of Optical Properties of 3d and 4f Ions

“…Yttrium orthoaluminate (also called sometimes yttrium aluminum perovskite, YAP) is a host suitable for solid state lasers, optical recording media etc (27)(28)(29). It belongs to the class of the wide gap materials, with the band gap width of about 8.8 eV (30). According to the data from Ref.…”

Shallow Traps in ${\rm YAlO}_{3}:{\rm Ce}$ Single Crystal Perovskites

“…, dashed line) shows an emission band centered at approximately 295 nm which is ascribed to an exciton-based center[13]-[15]. Low 0018-9499/$25.00 © 2008 IEEE…”

Intrinsic luminescence of YAlO3 perovskites

“…The A cations are distributed over the octahedral position formed by six oxygen ligands whereas B cations are located in the voids between the octahedrons created by the twelve nearest oxygen ions. The intrinsic UV luminescence of these compounds was mainly investigated for the case of YAlO 3 perovskites (YAP) and usually consists of two or more bands in the UV region [1][2][3][4]. The positions and intensities of these bands depend on the method of material preparation, type and concentration of host defects [3,4].…”