Analysis of waveguide architectures of InGaN/GaN diode lasers by nearfield optical microscopy
| Autor: | Jens W. Tomm, Sebastian Friede, Hans Wenzel, Veit Hoffmann, Sergei Kühn |
|---|---|
| Rok vydání: | 2017 |
| Předmět: |
010302 applied physics
Materials science business.industry Gallium nitride 02 engineering and technology 021001 nanoscience & nanotechnology Laser Indium gallium nitride 01 natural sciences law.invention Semiconductor laser theory chemistry.chemical_compound Optics chemistry law 0103 physical sciences Optoelectronics Near-field scanning optical microscope 0210 nano-technology business Waveguide Quantum well Diode |
| Zdroj: | SPIE Proceedings. |
| ISSN: | 0277-786X |
| DOI: | 10.1117/12.2249563 |
| Popis: | Waveguide (WG) architectures of 420-nm emitting InAlGaN/GaN diode lasers are analyzed by photoluminescence (PL) and photocurrent (PC) spectroscopy using a nearfield scanning optical microscope (NSOM) for excitation and detection. The measurements with a spatial resolution of ~100 nm are implemented by scanning the fiber tip along the unprepared front facets of standard devices. PL is collected by the fiber tip, whereas PCs are extracted from the contacts that are anyway present for power supply. The mechanisms of signal generation are addressed in detail. The components of the ‘optical active region’, multiple quantum wells (MQW), WGs, and cladding layers are separately inspected. Even separate analysis of p- and n-sections of the WG become possible. Defect levels are detected in the p-part of the WG. Their presence is consistent with the doping by Mg. An increased efficiency of carrier capture into InGaN/GaN WGs compared to GaN WGs is observed. Thus, beyond the improved optical confinement, the electrical confinement is improved, as well. NSOM PL and PC at GaN based devices do not reach the clarity and spatial resolution for WG mode analysis as seen before for GaAs based devices. This is due to higher modal absorption and higher WG losses. NSOM based optical analysis turns out to be an efficient tool for analysis of single layers grown into InAlGaN/GaN diode laser structures, even if this analysis is done at a packaged ready-to-work device. |
| Databáze: | OpenAIRE |
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