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Embedded GaN nanostripes on c ‐sapphire for DFB lasers with semipolar quantum wells
Author(s) -
Leute Robert A. R.,
Heinz Dominik,
Wang Junjun,
Meisch Tobias,
Müller Marcus,
Schmidt Gordon,
Metzner Sebastian,
Veit Peter,
Bertram Frank,
Christen Jürgen,
Martens Martin,
Wernicke Tim,
Kneissl Michael,
Jenisch Stefan,
Strehle Steffen,
Rettig Oliver,
Thonke Klaus,
Scholz Ferdinand
Publication year - 2016
Publication title -
physica status solidi (b)
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.51
H-Index - 109
eISSN - 1521-3951
pISSN - 0370-1972
DOI - 10.1002/pssb.201552277
Subject(s) - materials science , optoelectronics , laser , sapphire , quantum well , cathodoluminescence , wafer , lithography , electron beam lithography , molecular beam epitaxy , transmission electron microscopy , optics , epitaxy , resist , nanotechnology , luminescence , layer (electronics) , physics
Abstract 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 250 nm 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 170 nm periodicity are fabricated by electron beam lithography and SAE.