Epitaxial growth and the electronic structure of MgSe on ZnSe/GaAs (001)

• Published in: Journal of electron spectroscopy and related phenomena Vol. 114; pp. 527 - 532
• Main Authors: Feng, P., Gard, F., Riley, J.D., Pigram, P.J., Leckey, R., Seyller, Th, Ley, L.
• Format: Journal Article
• Language: English
• Published: Elsevier B.V 01-03-2001
• Subjects: Electronic structure; Epitaxy; Interface; Semiconductor; Semiconductor; Electronic structure; Epitaxy; Interface
• ISSN: 0368-2048; 1873-2526
• DOI: 10.1016/S0368-2048(00)00357-1

We have examined the growth and electronic properties of thin layers of MgSe on relaxed 0.6 μm ZnSe epilayers. This avoids potential complications when MgSe is grown directly on GaAs substrates. Using relatively low energy photons from the BESSY1 synchrotron radiation facility to enhance the photoemission cross-sections, we have monitored the evolution of the 3
d core levels of Zn, and Se together with the 2
s and 2
p levels of Mg as a function of MgSe layer thickness, using the technique of angle resolved photoemission. By using a substrate temperature of 350°C, we obtained consistently good c(2×2) LEED patterns after each evaporation cycle: the maximum MgSe thickness investigated was 3.2 nm. From an examination of the energy shift of the substrate Se 3
d level following MgSe deposition (attributed to band bending) and determination of the apparent shift in the position of the valence band maximum, we estimate the true value of the valence band offset as −0.34 eV (relative to ZnSe). Both surface and “bulk” Se contributions have been identified and an estimate of 0.44 nm for the inelastic mean-free-path of 56 eV electrons in MgSe has been derived. Normal emission valence band data utilizing a wide range of photon energies has been used to determine the band structure of MgSe (001) for the first time using the usual assumptions associated with a free electron final state model. Using an inner potential of 9.1 eV we find the binding energies of the
X
5 and
X
3 points to be 1.5 and 3.85 eV respectively relative to the valence band maximum.