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Pros and cons of green InGaN laser on c ‐plane GaN
Author(s) -
Strauß Uwe,
Avramescu Adrian,
Lermer Teresa,
Queren Désirée,
GomezIglesias Alvaro,
Eichler Christoph,
Müller Jens,
Brüderl Georg,
Lutgen Stephan
Publication year - 2011
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.201046299
Subject(s) - indium , quantum well , optoelectronics , materials science , laser , polar , quantum efficiency , quality (philosophy) , layer (electronics) , optics , physics , nanotechnology , quantum mechanics , astronomy
The challenges of green InGaN lasers are discussed concerning material quality as a function of InGaN composition, quantum well design and piezoelectrical fields. Investigations of polar quantum well designs and comparison with simulated non‐polar structures demonstrate that the quality of the indium rich layers is more important than the influence of interface charges. A high risk of dark spots at high In concentrations of 26–33% is observed. Small changes of about 2% of In significant reduce or increase the quantity and size of dark luminescence areas. Polar designs are a trade‐off between low indium concentrations of 4 nm wide quantum wells and high overlap of electrons and holes in 2 nm narrow designs. Furthermore, our single quantum wells have less non‐radiative defects than indium rich multi‐quantum well structures. Optimized active layer designs and the material qualities enable us to get green InGaN lasers on c ‐plane substrates for cw operation at 515–524 nm and wall plug efficiencies of 3.9–2.3%. Slope efficiency of 0.3–0.4 W/A allows up to now highest optical output power of 50 mW.