| About this Abstract |
| Meeting |
2011 Electronic Materials Conference
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| Symposium
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2011 Electronic Materials Conference
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| Presentation Title |
MM4, Wet Etching Technique for Fabrication of GaSb Based Mid Infrared Single Lateral Mode Lasers |
| Author(s) |
Seungyong Jung, Sergey Suchalkin, Leon Shterengas, Gela Kipshidze, Gregory Belenky |
| On-Site Speaker (Planned) |
Seungyong Jung |
| Abstract Scope |
GaSb based mid infrared (IR) light sources and detectors are in high interests due to applications including gas sensing, medical diagnosis, and infrared imaging. Etching is a necessary step in the fabrication procedure of single lateral mode ridge lasers, LED arrays, and detectors. Most of the narrow ridges for laser structures have been formed using dry etching since it can provide precise control of etching depth and the mesa wall steepness. Simplicity of the implementation and low cost are among the advantages of the wet etching. One of the main problems of a wet etching technique is precise control over the etching depth and mesa width, the parameters which are crucial for fabrication of single lateral mode ridge lasers. Fabrication of narrow mesas using wet etching is especially difficult due to the etching undercut and material selectivity of most of the etching solutions.
We suggest a wet etching procedure based on two etching solutions with complementary selectivity. Hydrochloric acid (HCl) based solution works well on aluminum containing layers, while sodium hydrogen-tartrate based etchant etches faster the materials without aluminum. Introducing an AlInGaAsSb etch-stopping layer with reduced Al content into the Al-rich cladding layer of the laser structure makes possible to control the etching depth with high accuracy.
The ridge lasers were fabricated from GaSb-based type-I quantum well laser structure emitting near 2 µm. For this wavelength, the laser mesa width less than 8 µm is required to ensure single lateral mode operation. The 50 nm thick AlInGaAsSb etch-stopping layer was placed 200 nm over the waveguide. Tartrate etchant was applied to remove the GaSb cap and part of the upper cladding layer. HCl etchant was subsequently used to control the width of the ridge.
The 6-µm wide ridge laser with nearly vertical sidewall was obtained using the above etching technique. The laser generated the continuous wave power of 67 mW at 20°C and the threshold current density was 416A/cm<SUP>2</SUP> (50 mA). Full width at half maximum of slow axis angle distribution was 10 degrees, which exhibited diffraction limited output beam.
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| Proceedings Inclusion? |
Undecided |