High-Indium-content nonpolar quantum wells for green, yellow, and red light emitters

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The lack of control of polarization fields is presently a major factor limiting application of III-nitride based heterostructures for green and longer wavelength light-emitting devices, including green laser diodes.By controlling polarization fields through the use of non-polar orientations we aim at opening the door for better visible light emitters. Epitaxial growth of non-polar heterostructures will be studied and optimized for low defect densities, abrupt interfaces and homogeneous compositions. The emphasis is on GaInN quantum wells with high Indium content suited for green and longer wavelength applications. As a key, Indium incorporation beyond 30% needs to be controlled maintaining full lattice-matching as well as fully homogeneous and stochiometric growth.Time-resolved optical spectroscopy as well as optical gain spectroscopy reveal the influence of nonradiative recombination losses, both due to defects and to intrinsic recombination. Direct information about defect levels is obtained through resonant photocurrent noise spectroscopy. In collaboration with partners from the Research Group, the non-polar approach will be compared to the semipolar and the polar approach.