Skip to Main Content
 

Global Search Box

 
 
 
 

Files

File List


case1207231457.pdf (3.27 MB)

ETD Abstract Container

Abstract Header

Studies in the Growth and Properties of ZnGeN2 and the Thermochemistry of GaN

Peshek, Timothy John
http://rave.ohiolink.edu/etdc/view?acc_num=case1207231457

Abstract Details

2008, Doctor of Philosophy, Case Western Reserve University, Physics.
The first reported growth experiments of ZnGeN2 from the melt are described. Early experiments yielded hexagonally faceted platelets 3-5 microns wide by about 2-3 microns thick. The vapor-liquid-solid (VLS) growth mechanism was then used to grow single crystalline rods of ZnGeN2, also hexagonally faceted, and 3-5 microns wide by 20-40 microns long. A detailed discussion ofthe growth mechanism is provided. Micro-Raman spectroscopy of the VLS grown crystals showed many well-resolved peaks in excellent agreement with theoretical calculations for ZnGeN2 in the orthorhombic structure. Analysis of the micro-Raman spectra indicates a partial ordering of the cation sublattice; that is, the material exhibits characteristics of both the wurtzite and orthorhombic structures. The Gibbs free energy of formation of GaN was measured by estimating the equilibrium pressures of N2 over Ga/GaN as a function of temperature. The experiment returned values of ΔH0f(298 K) = -165(16) kJ/mol and S0(298 K) = 19(14) J/mol/K for the enthalpy change of formation and absolute entropy of GaN, respectively. These results are inconsistent with widely-quoted values for the free energy and enthalpy change of formation of GaN. The minimum partial pressure of NH3 in H2 for the stable growth of GaN was measured as a function of flow rate through the reactor and temperature. A model was developed that showed the partial pressures of the gases approach their equilibrium values over Ga/GaN as the flow rate increases. These data were used to define an upper bound on the standard Gibbs free energy, which is consistent with the equilibrium N2 measurements but excludes many widely-quoted values.
Kathleen Kash, Ph.D. (Advisor)
John Angus, Ph.D. (Committee Member)
Walter Lambrecht, Ph.D. (Committee Member)
Gary Chottiner, Ph.D. (Committee Member)
151 p.
Physics
GaN; ZnGeN2; Thermochemistry; Enthalpy; Raman Spectroscopy

Recommended Citations

Citations

  • Peshek, T. J. (2008). Studies in the Growth and Properties of ZnGeN2 and the Thermochemistry of GaN [Doctoral dissertation, Case Western Reserve University]. OhioLINK Electronic Theses and Dissertations Center. http://rave.ohiolink.edu/etdc/view?acc_num=case1207231457

    APA Style (7th edition)

  • Peshek, Timothy. Studies in the Growth and Properties of ZnGeN2 and the Thermochemistry of GaN. 2008. Case Western Reserve University, Doctoral dissertation. OhioLINK Electronic Theses and Dissertations Center, http://rave.ohiolink.edu/etdc/view?acc_num=case1207231457.

    MLA Style (8th edition)

  • Peshek, Timothy. "Studies in the Growth and Properties of ZnGeN2 and the Thermochemistry of GaN." Doctoral dissertation, Case Western Reserve University, 2008. http://rave.ohiolink.edu/etdc/view?acc_num=case1207231457

    Chicago Manual of Style (17th edition)

case1207231457
1,901
© 2008, all rights reserved.
This open access ETD is published by Case Western Reserve University School of Graduate Studies and OhioLINK.