4.1 Brightness vs. voltage for ZnS:ErF3 as-deposited and annealed half and full
 stack devices ........................... ......... ........ ............ ..........................5 1

4.2 Infrared emission spectrum of (a) as-deposited, (b) annealed ZnS:ErF3 half vs.
 full stack devices ......................................................................55

4.3 Ratio of the 1550nm peak to the 980nm peak (at V40) for ZnS:ErF3 half and
 full stack devices in the as deposited or annealed conditions. ................................57

4.4 Visible emission spectrum of ZnS:ErF3 as-deposited and annealed half-stack vs.
 full-stack devices ................ ....................... ............... ...... ....... 58

4.5 Ratio of the 1550nm to 550nm peak intensities (at V40) for ZnS:ErF3 half and
 full stack devices in the as deposited or annealed conditions. ................................59

4.6 Q-V data at V40 from (a) as-deposited, (b) annealed ZnS:ErF3 half-stack vs. full-
 stack devices .............. ........... ....................... ...................... 62

4.7 Qext vs. time showing the value of Qint for a half-stack as-deposited ZnS:ErF3
 dev ice. ..............................................................................63

4.8 Capacitance vs. voltage data for (a) as-deposited, (b) annealed ZnS:ErF3 half-
 stack vs. full-stack devices. ...... ........................... ....................................... 65

4.9 Brightness vs. voltage for ZnS:TmF3 as-deposited half and full stack devices.......66

4.10 Visible red and near-infrared emission spectrum of as-deposited ZnS:TmF3
 half-stack vs. full-stack devices. ........................................ .......................... 68

4.11 Visible blue emission spectrum of as-deposited ZnS:TmF3 half-stack vs. full-
 sta c k d ev ic e s ...................................... .............................. ................ 6 9

4.12 Q-V curve at V40 from as-deposited ZnS:TmF3 half-stack vs. full-stack
 d e v ic e s ........................................................................... 7 1

4.13 Capacitance vs. voltage curves for as-deposited ZnS:TmF3 half-stack vs. full-
 sta c k d ev ic e s ...................................... .............................. ................ 7 3