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INTRODUCTION
Reection high-energy electron diHiraction (RHEED)
uses a Rnely collimated electron beam with energy of
10-100 keV. The beam irradiates a sample surface with
gazing incidence to obtain forward scattered difraction
patterms. RHEED enables us to analyze structures of
crystal surfaces at atomic levels and also to in situ
monitor growth processes of thin films (mo、1988:
Ichimiya and Cohen、2004: Peng et al.. 2011). From the
arrangement。intensity and profile of the dilraction
spots in RHEED patterns as described below in detail、
one can obtain various kinds of information: (1) the
periodicity (unit cells) in atomic arrangements. (2) flat-
ness of surfaces. (3) sizes of grains/domains of surface
structures and microcrystals grown on the surface.
(3) epitaxial relation between the grown flms/islands
with respect to the substrate. (5) parameters character-
izing structural phase transitions. (6) individual atomic
positions in the unit cells. and (7) growth styles of thin
films and numbers of atomic layers grown.
The most important advantages of the method are
that it is quite easy to install the RHEED apparatus in
Yarious types of vacuum chambers without interfering
with other components of apparatuses and to do real-
time monitoring during thin-Rlm growths. Because of
these advantages.RHEED is nowwidelyusednotonlyin
research Iabs of surfaces and thin fims. but also in
device production processes in industry
Low-energy electron diiraction (LEED、see article
Low-ENNERcy ErecroN DirscmoN)。 in which an electron
beam of 10-100 eV in energy is irradiated onto a sample
surface with nearly normal incidence to obtain back-
scattered difraction patterns. is also widely used to
analyze the atomic structures of crystal surfaces. Since
one has to make the sample face directly to the LEED
