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.
.