Regensburg 2016 – wissenschaftliches Programm
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HL: Fachverband Halbleiterphysik
HL 23: Oxide Semiconductors I
HL 23.7: Vortrag
Dienstag, 8. März 2016, 11:30–11:45, H13
Influence of incoherent twin boundaries on the electrical properties of homoepitaxial β-Ga2O3 layers grown by metal organic vapor phase epitaxy — •Andreas Fiedler, Klaus Irmscher, Robert Schewski, Martin Albrecht, Michele Baldini, and Günter Wagner — Leibniz-Institute for Crystal Growth, Max-Born-Str. 2, 12489 Berlin, Germany
Doped β-Ga2O3 layers have been grown homoepitaxially on (100) orientated substrates by metal organic vapor phase epitaxy (MOVPE) using either the shallow donor impurity Sn or Si. Conductivity and Hall effect measurements at room temperature show n-type conductivity. However, the measured electron concentrations between 5× 1017 cm−3 and 2× 1019 cm−3 indicate a strong electrical compensation and the electron mobilities of up to 30 cm2V−1s−1 unexpectedly decline for low carrier densities. A possible explanation for this behavior comes from a structural analysis by transmission electron microscopy (TEM). It reveals that the layers contain a high density of planar defects consisting of twin lamellas and stacking faults. The lateral twin boundaries are incoherent and contain dangling bonds that trap charge carriers. This leads to charge accumulation and hinders lateral charge carrier transport. This behavior is in analogy to that of dislocation walls treated in [1]. Based on this model, we explain the observed steep decline in electron mobility at low carrier concentrations. Furthermore, the strong compensation of the donor dopants can, at least partly, be ascribed to the acceptor effect of the incoherent twin boundaries.
Farvacque et al., Physical Review B 63 115202 (2001).