Berlin 2015 – wissenschaftliches Programm

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HL: Fachverband Halbleiterphysik

HL 40: Focus Session: Role of polarization fields in nitride devices I

HL 40.3: Vortrag

Mittwoch, 18. März 2015, 10:15–10:30, ER 164

Structural and optical properties of MOVPE grown InGaN/AlInGaN MQWs — •Silvio Neugebauer, Jürgen Bläsing, Armin Dadgar, and André Strittmatter — Institute of Experimental Physics, Otto-von- Guericke-University Magdeburg, Germany

Conventional InGaN/GaN light emitting diodes designed for the green spectral range lack in efficiency due to spontaneous and piezoelectric polarization fields. These fields have negative impact on the LED performance by reducing the recombination probability and wavelength stability of the active medium which is known as the quantum-confined Stark effect. Better device performance could be possibly achieved by using AlInGaN barriers instead of conventional GaN barriers. For a particular InGaN composition it is possible to eliminate the difference in total polarization across the QW/barrier interface by choosing a proper AlInGaN composition. In this context InGaN/AlInGaN MQWs have been grown by MOVPE. Within a set of samples the composition of the barriers have been varied from pure GaN to fully polarization-matched AlInGaN with respect to the InGaN. For better compositional and structural control, these AlInGaN barriers have been grown using the pulsed flow regime. In PL experiments we observe a blueshift of the MQW emission with increasing nominal polarization matching of the barriers. This is consistent with reduced electric fields across the quantum well region. Unfortunately, the whole MQW stack gets additionally strained due to the high indium content of the AlInGaN barrier leading to lattice relaxation as revealed by XRD.