Raman scattering studies of the ZnSe/GaAs interface

Abstract

Raman spectroscopy was used to study the band bending at the interface of ZnSe/GaAs hetero-structures. A series of samples, which contained a ZnSe buffer layer, 0-35 nm thick, grown at a lower temperature than the much thicker ZnSe epilayer, by metal-organic chemical vapor phase deposition, were investigated. Compared with that of the GaAs substrate, an enhancement of the intensity of the LO GaAs phonon was found in samples grown without and with a thick (≥28 nm) buffer layer, but not in a sample grown with a 4 nm thick buffer layer. The enhancement is attributed to the electric field induced Raman scattering, resulted from a strong band bending on the GaAs side of the hetero-structure. The results suggest that the direction of the interfacial electric field on the GaAs side will reverse with increasing buffer layer thickness. Between this reversal, a near flat band condition can be achieved, as was found in a sample grown with a 4 nm buffer layer. This suggestion is consistent with the concomitant improvement of the structure of the epilayer and of the interfacial quality of the hetero-junction, which unpins the Fermi level and affects the band bending.

Raman spectroscopy from buried semiconductor interfaces: Structural and electronic properties

“…The ZnSe/GaAs(001) system has been subject of many Raman studies, which focus to various aspects, such as e.g. the reactivity of the interface , the analysis of compound formation, microstrain , strain profiles , disorder , growth mechanism in atomic layer epitaxy , precursor dependence in MOVPE , in situ growth monitoring , post‐growth annealing effects , electronic band bending and electric fields , interfacial charge carriers in nominally undoped samples , and the generation of photo‐carriers by laser irradiation .…”

Raman Spectroscopic Studies of ZnSe/GaAs Interfaces

“…Raman spectroscopy is the suitable technique for nondestructive characterization of the structural and electronic properties for the substrate side of the interface of large gap / small gap semiconductor heterostructures. A typical example is ZnSe/GaAs heterostructure which has received intense interest through experimental and theoretical studies over the last two decades [1][2][3][4][5][6][7][8] due to its importance in laser action that has been achieved in ZnSe [9] and development electronic devices. In this system, high quality crystals can be grown due to the small lattice mismatch (<0.27%) between ZnSe and GaAs however, a thin ZnSe/GaAs heterostructure suffers internal strains.…”