Summer 2010 Intern Project- Christopher Roberts

POLARIZATION SWITCHING ON InGaN LED

Christopher Roberts
Physics
UC Santa Barbara

Mentors: Qimin Yan, Maosheng Miao
Faculty Advisor: Chris Van de Walle
Department: Materials Science

The polarization of light is an important aspect of many lighting and display technologies. Due to the anisotrophic nature of the wurtzite crystal structure, light emitted from InGaN/GaN quantum wells may switch polarization with increasing indium composition, a property that also depends on growth orientation. Previous experimental research suggests this polarization switching occurs between 30-50% indium concentration for the (11-22) growth direction. By solving the coupled Schrodinger-Poisson equations self-consistently, and applying a 6x6 k*p approximation, we are able to investigate these effects for a full range of compositions for both quantum well and bulk material. Our simulations show that the separation energy of the highest two valence bands is directly related to plane rotation angle, regardless of rotation axis. Polarization switching is discussed in detail for both bulk material and quantum well structure.

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