Cathodoluminescence microscopic studies of α-HgI_2 platelets and crystals

Abstract

CathodoLuminescence studies (CL) have been carried out on red mercuric-iodide (α-HgI_2) crystals and platelets grown by the vapor transport method. Panchromatic CL images revealed inhomogeneous distribution of growth-induced dislocations and terraces. The effect of prolonged KI (20%) treatment on the evolution of different CL bands has been investigated. CL spectra of the platelets at 80 K showed three luminescence bands at about 546, 567 and 624 nm. The intensity of the 567 nm band (band II) decreased after KI treatment, thus indicating the role of I vacancies on the evolution of this band. An additional band at about 555 nm is observed in as-grown crystals, but not revealed in platelets. Increase of the relative intensity of band III (624 nm) on prolonged KI treatment indicates the association of some surface states on this band along with the effect of impurities as reported earlier. Hg treatment causes an increase of total CL intensity and also the relative intensity of band II in platelets and crystals.