Heterogeneously bonded vertical cavity surface emitting lasers and thermal modeling

Jeong, Hyejin

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https://hdl.handle.net/2142/46758 Copy

Description

Title

Heterogeneously bonded vertical cavity surface emitting lasers and thermal modeling

Author(s)

Jeong, Hyejin

Issue Date

2014-01-16T18:01:28Z

Director of Research (if dissertation) or Advisor (if thesis)

Choquette, Kent D.

Doctoral Committee Chair(s)

Choquette, Kent D.

Committee Member(s)

• Goddard, Lynford L.
• Kim, Kyekyoon
• Rogers, John A.

Department of Study

Electrical & Computer Engineering

Discipline

Electrical and Computer Engineering

Degree Granting Institution

University of Illinois at Urbana-Champaign

Degree Name

Ph.D.

Degree Level

Dissertation

Keyword(s)

• vertical cavity surface emitting lasers (VCSEL)
• semiconductor
• laser
• fabrication
• hybrid
• electro-thermal
• modeling
• COMSOL
• bonding
• heterogeneous substrate

Abstract

Typically semiconductor materials used for photonic devices have been limited to those exhibiting a direct bandgap. In order to incorporate indirect bandgap and non-semiconducting materials, extensive research efforts have been put into developing hybrid photonic devices, which consist of different materials for the light emitting region and the substrate. In this dissertation, a post-fabrication bonding technique for integrating semiconductor vertical cavity surface emitting lasers (VCSELs) onto hybrid substrates is demonstrated. This approach provides flexibility regarding the choice of device fabrication and hybrid substrate materials. Light output versus injected current and applied voltage characteristics of lasers are measured before and after the transfer process. VCSEL arrays transferred onto Si substrate show that the transfer technique does not degrade the laser performance. VCSEL transfer onto a polyethylene terephthalate (PET) substrate allows for flexible arrays, but with degraded performance due to excessive thermal dissipation. A VCSEL array with an area of 1.0 x 1.2 mm2 is transferred onto a Cu substrate which has a higher thermal conductivity compared to both GaAs and PET. For the transfer bonding process, the final device yield is enhanced by including an etch stop layer in the epitaxial wafer. In order to study the effect of the thermal conductivity of the substrate on the dissipation of heat from the VCSELs, we present a simple VCSEL electro-thermal model, in which an agreement is obtained between simulation and experiment for lasing wavelength with varying laser diameter. Using this model, the thermal limitations of the VCSEL output on different substrates is discussed

Graduation Semester

2013-12

Permalink

http://hdl.handle.net/2142/46758

Copyright and License Information

Copyright 2013 Hyejin Jeong

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