Process development of halide transport chemical vapor deposited (HTCVD) ZnS:Mn thin film has been studied. To this end, electrical characterization of HTCVD ZnS:Mn electroluminescent devices has been used. Process optimization focused on a simple design of experiment (DOE) with brightness as the major response. Deposition parameters such as HCl and H���S gas flow rates, ZnS and Mn source temperatures and substrate temperature were studied. A substrate temperature of 550��C gives the brightest devices. ZnS source temperature and H���S gas flow rate are insignificant parameters according to the statistical analysis. However HCl gas flow rate and Mn source temperature show strong interaction. It is proposed that the incorporation of Cl into the ZnS:Mn film causes the interaction. A Cl defect is also consistent with anomalous electrical behavior observed in the devices. Cl defects are thought to precipitate at the grain boundaries of the initial growth interface, then diffuse (or migrate) along the grain boundaries and possibly into the bulk crystal. This defect will easily form negative charge leading to asymmetric space charge in the bulk of the phosphor. Since the defects are believed to originate from the nucleation of Cl at high grain boundary density, one potential solution is to remove the Cl source as the grains begin to grow and only later expose the film to Cl. While film growth without HCl present at the beginning of deposition leads to brighter films, it is a sub-optimal solution. Part of the ZnS host does not have luminescent centers. It is believed other processing solutions need to be realized to make the HTCVD system viable. / Graduation date: 1999

Graduation date: 1999

A low pressure halide transport chemical vapor deposition (HTCVD) system to grow ZnS:Mn electroluminescent phosphors is characterized. Reactor parameters such as gas composition, gas flow rate, and source and substrate temperature are investigated. Crystal structure is investigated using x-ray diffraction, electron spin resonance, and transmission electron microscopy. Chemical characterization includes electron microprobe and Auger electron spectroscopy. Double-insulating alternating current thin film electroluminescent devices are constructed around the HTCVD phosphors. The devices are studied using electroluminescence (brightness-voltage), photoluminescence and electrical characterization. The luminescent properties of films with a (002) preferred orientation are studied. A maximum electroluminescent brightness of 1475 cd/m�� is achieved. The photoluminescence (PL) of ZnS:Mn films grown at different substrate temperatures is compared. The intensity correlates to Mn concentration. Red emission is seen in films grown at lower substrate temperature which have low Mn concentration. Mechanisms proposed in the literature cannot explain the red emission. A blue PL ZnS film intentionally doped with chlorine is achieved. This blue emission is associated with self-activated (SA) emission. Hexagonal and cubic thin-film ZnS:Mn electroluminescent phosphors are grown by HTCVD. Processing conditions, most notably introduction of a H���S ambient, lead to a change in the preferred orientation and phase of the polycrystalline thin film. In addition to the commonly reported growth along the closest packed plane [(111) for cubic crystal structure or (002) for hexagonal], thin films have been grown along the less dense cubic (311) direction. The electrical characterization of ZnS:Mn ACTFEL devices with phosphors having different structure and preferred orientation is studied. A comparison of different preferred orientations and structures on conduction charge, obtained by internal charge-phosphor field (Q-F[subscript]p), is performed. When grown in the (311) direction, the conduction charge of a ZnS:Mn ACTFEL device increases from 2.3 ��C/cm�� to 5.0 ��C/cm��. Moreover, the leakage charge, Q[subscript]l[subscript]e[subscript]a[subscript]k, of the (311) HTCVD films is small compared to other devices. / Graduation date: 1998

Graduation date: 1997

Graduation date: 1995

No description available.

Graduation date: 1994

Thesis (Ph. D.)--Oregon State University, 2008. / Printout. Includes bibliographical references. Also available on the World Wide Web.

Thesis (M.Sc.)--Victoria University of Wellington, 2008. / CD-ROM contains scattering simulation code, Mie theory code and the LabView driver to run the experiment. Includes bibliographical references.

Thesis (M.S.)--University of Kentucky, 2003. / Title from document title page (viewed Sept. 10, 2004). Document formatted into pages; contains xii, 140 p. : ill. Includes abstract and vita. Includes bibliographical references (p. 139).