Distributed feedback lasers formed via aspect ratio trapping

Abstract

Structures including dielectric diffraction gratings. In some embodiments, laser devices include diffraction gratings defined by openings formed in a dielectric material.

Description

RELATED APPLICATION[0001]This application claims priority to U.S. Provisional Patent Application Ser. No. 60 / 852,781, filed Oct. 19, 2006, the disclosure of which is hereby incorporated by reference in its entirety.FIELD OF THE INVENTION[0002]This invention relates generally to semiconductor processing and particularly to formation of light-emitting devices based on lattice-mismatched semiconductor structures.BACKGROUND[0003]Distributed feedback (DFB) lasers with stable longitudinal single-mode operation are critical for applications such as optical-information processing, interferometric measuring, holographic printing, optical gas sensing, atomic spectroscopy and medical diagnoses. Examples of various DFB lasers are shown and described in U.S. Pat. Nos. 5,295,150 and 5,953,361 and articles such as Japanese Journal of Applied Physics, Vol. 43, No. 4B, 2004, pp. 2019-2022, Japanese Journal of Applied Physics Vol. 44, No. 4B, 2005, pp. 2546-2548, and Journal of Crystal Growth 261 (20...

AI Technical Summary

Benefits of technology

[0006]Low-cost Si may be used as the substrate. Si-based device fabrication technology is more mature than that of III-V compound materials. In addition to significant wafer cost reduction, adapting large-wafer Si processing techniques for III-V laser device processing may enhance the DFB fabrication reliability and product yield, thus leading to better device performance and further reduction of fabrication cost. In addition, a Si substrate has better thermal conductivity and a higher physical hardness than conventional GaAs and InP materials. Using Si as a substrate therefore improves heat depletion control and device packaging.

[0009]Another benefit is that ART patterning can provide a large refractive index difference between the dielectric material, e.g., SiO2 (1.46), and the epitaxially grown material, e.g., GaAs (3.2). This refractive index difference is larger than the refractive index difference between conventionally used materials such as GaAs and AlGaAs, and leads to a high optical coupling constant. The simplified grating formation procedure, which avoids a re-growth process, is another significant benefit in comparison to conventional methods of forming DFB structures.

[0010]The use of well developed integrated circuit (IC) processes for forming the grating pattern allows for flexibility in grating geometry because selection of grating duty cycle and the variation of grating pitches can be realized in an initial photolithography process. This offers advantages over conventional post-growth holographic techniques.

[0011]The approaches described herein for realizing III-V / Si integration coupled with integration with conventional Si-based process enable a variety of other benefits as well, such as accommodating chip-scale integration of DFB lasers with other electronic devices.

Problems solved by technology

These defects are generated at an interface between different materials, e.g., a III-V / Si interface, due to lattice mismatch and thermal-expansion differences between Si and III-V compounds.

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