Regensburg 2010 – scientific programme

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HL: Fachverband Halbleiterphysik

HL 34: Poster I: III-V Semiconductors

HL 34.32: Poster

Tuesday, March 23, 2010, 18:30–20:30, Poster D2

Intracavity contacts for nitride based monolithic surface emitters by focused ion beam processing — •Malte Fandrich, Heiko Dartsch, Christian Tessarek, Timo Aschenbrenner, and Detlef Hommel — Institut für Festkörperphysik - Halbleiterepitaxie, Universität Bremen, Otto-Hahn-Allee 1, 28359 Bremen, Germany

The realization of electrically driven nitride based vertical-cavity surface-emitting lasers (VCSELs) is challenging due to limitations in the conductivity of the distributed Bragg reflectors (DBRs). Therefore monolithic approaches are based on a doped cavity and one or two undoped DBRs. This requires the use of technologically complex intracavity contacts.

The presented process yields intracavity contacts applicable to monolithically grown VCSEL structures. Initially mesas are structured by photolithography and chemical assisted ion beam etching. The precise structuring of the prestructured mesas is performed in a focused ion beam system (FIB), where the micropillars are thinned stepwise down to a diameter of 0.5 - 5 µm. The contacting of the pillars is realized by FIB deposited metal and insulator structures. Insulator separated Pt ringcontacts connect the micropillars with large-scale contact pads. This procedure was applied to a VCSEL structure consisting of a bottom AlInN/GaN-DBR with 40 pairs, a p/n-doped 5 λ GaN-cavity with embedded InGaN quantum dots and a top 10 pair AlInN/GaN-DBR. The developed contacting structure enables a current up to 15 mA through the cavity which documents the capability for the electrical operation of VCSEL devices.