Dissertation
CHARACTERIZATION AND OPTIMIZATION OF DOPANTS, IMPURITIES, AND DEFECTS IN BULK OPTICAL AND SEMICONDUCTOR MATERIALS: CASE STUDIES ON ZnS, β-Ga2O3, AND Nd:YAG
Doctor of Philosophy (PhD), Washington State University
01/2019
Handle:
https://hdl.handle.net/2376/117575
Abstract
Defects are what make most optical and semiconductor materials interesting, versatile in their behavior, and useable in different applications. Defects at the level of one atom in 106 to 109 atoms of the host material can have a significant influence on the electrical and optical properties, and depending on the identity of the defect and the site it is occupying, they can either enhance, degrade, or have no effect on the properties. Thus, it is crucial to characterize and understand the role of various dopants/defects on the properties and performance optical and semiconductor materials, and the defect/dopant formation, incorporation, and variation.
This dissertation examines the influence of dopants and defects in ZnS, β-Ga2O3 and Nd:YAG. Finally, the implementation of the accelerated crucible rotation technique (ACRT) is described to modify the Nd concentration profile in YAG grown by Czochralski (CZ). ZnS is a well-known scintillator used mainly in the powder forms; this study examines using bulk ZnS as a scintillator by modeling. The study also evaluates bulk ZnS single crystals by photoluminescence (PL), PL excitation, optical absorption, radioluminescence, and thermoluminescence and shows that samples show diverse luminescence behavior that can be attributed to the differences between samples’ impurity concentrations. Study of the bulk ZnS by optical deep level transient spectroscopy (ODLTS), photoinduced current transient spectroscopy (PICTS), and photoconductivity shows the applicability of ODLTS/PICTS in studying ZnS, and show peculiar optically induced electrical behavior that is caused by a combination of point and extended defects. β-Ga2O3 is an ultra-wide bandgap transparent semiconducting oxide of interest for high breakdown voltage electronics. This study evaluates parameters that affect the Czochralski (CZ) growth of β-Ga2O3, and introduces two new shallow donors, Zr and Hf; these dopants show potentially superior electrical properties over other donors, such as Si and Sn, in β-Ga2O3 and the ability to degenerately dope β-Ga2O3. Finally, Nd:YAG is an important laser material that suffers from dopant segregation. In this study, we use ACRT to modify the Nd radial and vertical concentration profile during the CZ growth of Nd:YAG and enable enhanced incorporation of Nd, better homogeneity, and lower stresses.
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Details
- Title
- CHARACTERIZATION AND OPTIMIZATION OF DOPANTS, IMPURITIES, AND DEFECTS IN BULK OPTICAL AND SEMICONDUCTOR MATERIALS: CASE STUDIES ON ZnS, β-Ga2O3, AND Nd:YAG
- Creators
- Muad Saleh
- Contributors
- John S McCloy (Advisor)Kelvin G Lynn (Advisor)Matthew D McCluskey (Committee Member)
- Awarding Institution
- Washington State University
- Academic Unit
- Materials Science and Engineering Program
- Theses and Dissertations
- Doctor of Philosophy (PhD), Washington State University
- Number of pages
- 311
- Identifiers
- 99900581502101842
- Language
- English
- Resource Type
- Dissertation