In this work

the heteroepitaxial structure GaP/Si grown by Gas Source-Molecular Beam Epitaxy (GS-MBE) has been investigated by using X-ray Photoelectron Spectroscopy (XPS) depth profile measurements. The experimental results show that: (1) P

Ga peaks in XPS spectra within epilayer coincided with those of GaP phase. The components of P

Ga in the epilayr were distributed homogeneously correponding to GaP stoichiometry except for rich P existing in the surface

although the epitaxy proceeded in relative rich

3

environment. (2) There is the same quality of the samples GaP/Si grown by GS-MBE under the different flowing rates of rich

3

and no obviously rich P has been found at the GaP/Si interface as well

except for slightly different amount of rich P existing in the surface. (3) In the vicinity of the GaP/Si interface

the peaks Si2p of the XPS spectra moved upwards to high binding energy terminal as Ar

+

etching GaP/Si until the substrates Si

but any other XPS peaks shift had not been found. The experimental binding energy of Si2p was higher than the expected p-Si substrates

approaching the binding energy of n-Si. (4) The C

O and other contamination scarcely existed in epitaxial layer and its interface within XPS detectability. All the experimental results revealed that the uncontaminated background UHV (Ultra High Va cuum)

relative rich

3

growing environment

and the successful process of cleaning Si substrate etc. were suitable for growth the stoichiometric heterostructrue GaP/Si.