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Techniques to reduce thermal resistance in flip‐chip GaN‐based VCSELs (Phys. Status Solidi A 8∕2017)
Author(s) -
MishkatUlMasabih Saadat,
Leonard John,
Cohen Daniel,
Nakamura Shuji,
Feezell Daniel
Publication year - 2017
Publication title -
physica status solidi (a)
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.532
H-Index - 104
eISSN - 1862-6319
pISSN - 1862-6300
DOI - 10.1002/pssa.201770149
Subject(s) - materials science , optoelectronics , flip chip , thermal resistance , cladding (metalworking) , chip , thermal , nanoimprint lithography , vertical cavity surface emitting laser , lasing threshold , thermal mass , optics , layer (electronics) , laser , wavelength , fabrication , nanotechnology , electrical engineering , composite material , medicine , physics , alternative medicine , engineering , pathology , meteorology , adhesive
The effects of several design geometries on the thermal resistance for a flip‐chip GaN‐based VCSEL with dielectric distributed Bragg reflectors was studied by Mishkat‐Ul‐ Masabih (article no. 1600819 ) using finite‐element analysis. The current flip‐chip design suffers from high thermal resistance, preventing devices to lase under CW operation. It was found that including a patterned DBR with recessed metal, reducing the lithography alignment tolerances, and increasing the aperture size; all contributed to the reduction of the thermal resistance of the design. In addition, epitaxially increasing the cladding layer thickness on either side of the active region also lowered the thermal resistance significantly. The thermal resistance values for previously reported CW device configurations were also calculated and compared to our flip‐chip design. The internal temperature changes at the threshold were estimated for the devices, indicating why previous generations of our flip‐chip devices could not achieve CW lasing. Combining these techniques, the effects of thermal roll‐over can be mitigated; as the reduction of the device temperature is a key consideration for obtaining high output power CW GaN‐based VCSELs.