High-pressure studies of photoluminescence and thermoluminescence of ZnS:Cu:Cl phosphors using laser selection excitation
- Univ. of Ilinois, Urbana, IL (United States)
The authors have measured the effect of pressure on the luminescence and thermoluminescence characteristics of three ZnS phosphors doped with Cu and Cl. The total dopant concentration varied in the ratio 1/1.5/2.5, but the Cl/Cu ratio was constant at {approximately}8/1. The excitation was via the 325-nm (3.82-eV) line of a He-Cd laser. The absorption edge of ZnS is at 3.67 eV at 1 atm and increases by 6.35 meV/kbar, so that at high pressure the excitation is to {open_quotes}deep levels{close_quotes} provided by the Cl. The emission consists of two peaks at 20,000 and 22,000 cm{sup {minus}1} assigned to emission from a Cl{sup {minus}} center to a Zn vacancy and a Cu{sup +} center, respectively. Both emission peaks increased in energy with pressure. The shifts could be explained in terms of the degree of pinning of donor and acceptor levels to the conduction and valence bands. The thermoluminescence data indicated an initial trap depth of 0.3 eV for all three samples. This trap depth increased with pressure at low pressures but leveled at 0.39, 0.46, and 0.54 eV for the high-, intermediate-, and low-concentration samples, respectively. The thermoluminescence intensity decreased by 2 orders of magnitude in 40 kbar. The behavior of the thermoluminescence could be explained largely by differences in the nature and behavior of the {open_quotes}deep levels{close_quotes} initially in the conduction band. 28 refs., 10 figs., 2 tabs.
- Sponsoring Organization:
- USDOE
- DOE Contract Number:
- FG02-91ER45439
- OSTI ID:
- 563378
- Journal Information:
- Journal of Physical Chemistry, Journal Name: Journal of Physical Chemistry Journal Issue: 1 Vol. 96; ISSN JPCHAX; ISSN 0022-3654
- Country of Publication:
- United States
- Language:
- English
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