Dresden 2009 – scientific programme

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HL: Fachverband Halbleiterphysik

HL 11: Focused Session: Semi- and nonpolar group III nitrides I

HL 11.6: Talk

Tuesday, March 24, 2009, 12:15–12:30, HSZ 01

Facet formation and ohmic contacts for laser diodes on non- and semipolar GaN — •Jens Rass¹, Simon Ploch¹, Tim Wernicke², Luca Redaelli², Patrick Vogt¹, Sven Einfeldt², and Michael Kneissl^1,2 — ¹Technische Universitaet Berlin, Institute of Solid State Physics, Secretariat EW6- 1, Hardenbergstrasse 36, 10623 Berlin, Germany — ²Ferdinand- Braun-Institut fuer Hoechstfrequenztechnik, Gustav-Kirchhoff-Str. 4, 12489 Berlin

Group-III-Nitride heterostructures grown on nonpolar and semipolar planes allow the realization of highly efficient devices such as laser diodes and LEDs due to the reduction or elimination of the quantum confined stark effect. However, the realization of these devices poses a number of challenges, in particular the formation of smooth laser facets and the fabrication of ohmic contacts.

In this talk optimized schemes for facet formation and contact resistance reduction for nitride based devices on non- and semipolar planes will be presented and various concepts will be discussed. We will discuss a laser scribing process that allows the cleaving of facets along the c- and a-plane for devices grown on nonpolar substrates. For semipolar planes there is no low-index cleavage plane in order to form resonators along the projection of the c-axis. Therefore we have investigated etching techniques in order to produce flat facets perpendicular to the plane of growth. For the challenging formation of p-type contacts to GaN we will discuss different methods such as chemical treatments, different metallization schemes and capping layers to reduce the contact resistivity.