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HL: Fachverband Halbleiterphysik
HL 7: III-V semiconductors I
HL 7.8: Talk
Monday, March 26, 2007, 12:45–13:00, H17
Comparison of the electronic band formation and band structure of GaNxAs1−x and GaNxP1−x — •Martin Güngerich1, Wolfram Heimbrodt1, Gerhard Weiser1, Bernardette Kunert1, Kerstin Volz1, Peter Jens Klar2, and John Franz Geisz3 — 1Fachbereich Physik und Wissenschaftliches Zentrum für Materialwissenschaften, Philipps-Universität, Renthof 5, D-35032 Marburg, Germany — 2I. Physikalisches Institut, Justus-Liebig-Universität, Heinrich-Buff-Ring 16, D-35392 Gießen, Germany — 3National Renewable Energy Laboratory, 1617 Cole Boulevard, Golden, Colorado 80401, USA
Incorporation of an increasing amount of N into GaAs causes a strong red shift of the fundamental band gap (E−) which is accompanied by the blue shift of a higher lying band of N impurity states (E+). This repulsive behaviour is successfully parameterized by a phenomenological two-level band-anticrossing (BAC) model. In GaP:N the energetic ordering of host and impurity states is reversed compared to GaAs:N because the localized levels lie within the host band gap. We show that the simple BAC model fails to describe the evolution of the lowest conduction states in GaNxP1−x. Photocurrent and electromodulated reflection measurements of GaNxP1−x support a BAC-related blue shift of its E+ band which in this material originates from the GaP-like lowest direct band gap. On the other hand, electromodulated absorption and pressure-dependent photoluminescence studies indicate that the wide energy distribution of the lower-lying N-related states leads to an anticrossing interaction involving many N levels.