From: kriman@acsu.buffalo.edu (Alfred M. Kriman)
Newsgroups: wny.seminar,ny.seminars
Subject: Dr. Prasad N. Gadgil; Fri. Oct. 16; MOCVD of Fool's Gold
Summary: CEEM Seminar -- 11:00 am in Rm 217A at Bonner Hall
Date: 14 Oct 92 21:55:12 GMT
Distribution: ny,ont
Organization: UB = University at Buffalo = SUNYAB = State U of New York At B

Seminar:
    +----------------------------------------------------------------------+
    |   Title:           MOCVD of Transition Metal Disulfides:             |
    |          Novel Liquid Precursors, Reactor Design and Thin Film FeS   |
    |                                                                   2  |
    | Speaker: Dr. Prasad N. Gadgil                                        |
    |      of: Simon Fraser University, Vancouver                          |
    +----------------------------------------------------------------------+

    Location: Room 217A of Bonner Hall, Amherst Campus of SUNYAB

        Date: Friday, October 16, 1992

        Time: 11:00-11:50 AM  (Refreshments 10:45 AM)

     Sponsor: Center for Electrical and Electro-optic Materials

 Shakespeare: All that glisters is not gold,
              Often have you heard that told.

ASCIIFIED ABSTRACT:
          ~~~~~~~~
     Transition metal disulfides, an unconventional and relatively less
studied class of compounds, have a wide variety of applications in thin film
photovoltaics, high energy-density batteries and heterogeneous catalysts, etc.
Iron pyrite with absorption length less than 0.1 microns, band gap about
1.0 eV, electron mobility 200 cm^2/V.s, and hole mobility ~2 cm^2/V.s has
shown tremendous promise as a thin film photovoltaic absorber material in
recent years.

     Herein, a few novel liquid precursors of sulfur which were successfully
employed to deposit iron pyrite thin films will be discussed.  Their physical
properties, vapor pressures, stability, mechanism of pyrolysis are compared
with the most common and a hazardous source of sulfur, hydrogen sulfide.
Peritectic decomposition of pyrite, thermodynamic and Fe-O-S phase relation-
ship considerations are presented for MOCVD processes for iron pyrite.  Such
factors clearly show necessity of a sulfur source that can deliver diatomic
sulfur species in vapor phase  at temperatures preferably below 300 Celsius.

     A novel stagnation-point flow CVD reactor design used for pyrite deposi-
tion is discussed.  Flow visualization results and fluid dynamical model for
gas distributor, inlet and wall effects and boundary layer thickness estima-
tion for optimization of CVD reactor design are presented.

     Finally, the results of the analysis of thin films of pyrite by XRD, SEM,
XPS and Mossbauer spectroscopies, variation of pyrite grain size and electri-
cal conductivity with deposition temperature and photoconductivity results are
presented.  Also, the potential applications of novel liquid sources and the
CVD reactor design studied here, in the II-VI and III-V MOCVD processes are
summarized.
_________
Guide to the perplexed:
   Yes, there are two CEEM seminars on Friday, Oct. 16.  If you dig epitaxial
growth, this is your lucky day.  Check the times and places carefully; they
are nonstandard.                 ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
^^^^^^^^^^^^^^^
Other Questions: Contact this poster at kriman@acsu.buffalo.edu
                 or (716) 645-3110.