Condensed Matter Seminar Series

Polarization properties of nonpolar GaN films and
(In,Ga)N/GaN multiple quantum wells

H. T. Grahn

Paul-Drude-Institut für Festkörperelektronik, Berlin, Germany

Thursday February 05, 11:00 am, Room 234, Physics Building

Host: Stephen Teitsworth

Abstract:  We have grown GaN films and (In,Ga)N/GaN multiple quantum wells (MQWs) by plasma-assisted molecular-beam epitaxy on gamma-LiAlO2(100) substrates. Due to the crystal symmetry of gamma-LiAlO2(100), GaN films and (In,Ga)N/GaN MQWs can be realized in a nonpolar (M-plane) configuration, i. e., the c-axis of the wurtzite unit cell lies in the growth plane. For compressively, anisotropically strained M-plane GaN films, the band structure of the valence band changes in such a way that the optical transmittance becomes 100% linearly polarized for two orthogonal in-plane directions, where one of these directions is parallel to the c-axis of the GaN film. The photoluminescence properties of M-plane In0.1Ga0.9N/GaN MQWs exhibit a strong in-plane optical anisotropy for linear polarization with an energy-dependent polarization degree of up to 96%, which is presumably also due to a large valence-band splitting induced by the large compressive strain in the QWs.


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