Leute R.A.R.,Ulm UniversityUlmGermany |
Heinz D.,Ulm UniversityUlmGermany |
Wang J.,Ulm UniversityUlmGermany |
Meisch T.,Ulm UniversityUlmGermany |
And 14 more authors.
Physica Status Solidi (B) Basic Research | Year: 2015
GaN based laser diodes with semipolar quantum wells are typically grown on free-standing pseudo-substrates of small size. We present an approach to create a distributed-feedback (DFB) laser with semipolar quantum wells (QWs) on c-oriented templates. The templates are based on 2-inch sapphire wafers, the method could easily be adapted to larger diameters which are available commercially. GaN nanostripes with triangular cross-section are grown by selective area epitaxy (SAE) and QWs are grown on their semipolar side facets. The nanostripes are completely embedded and can be sandwiched inside a waveguide. For optical pumping, open waveguide structures with only a bottom cladding are used. Using nanoimprint lithography, stripe masks with 250nm periodicity were fabricated over the whole wafer area. The periodicity corresponds to a 3rd order DFB structure for a laser emitting in the blue wavelength regime. These samples were analyzed structurally by high-resolution transmission electron microscopy (HRTEM), and spatio-spectrally by cathodoluminescence (CL) inside a scanning transmission electron microscope (STEM). Samples with an undoped cap are pumped optically for stimulated emission. To prove the feasibility of realizing a 2nd order DFB structure with this approach, stripes with a 170nm periodicity are fabricated by electron beam lithography and SAE. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.