AVS 46th International Symposium
    Electronic Materials and Processing Division Monday Sessions
       Session EM-MoA

Paper EM-MoA6
Process Development for Dry-etched Laser Facets on GaN

Monday, October 25, 1999, 3:40 pm, Room 608

Session: Nitride Processing and Characterization
Presenter: L. Zhang, Sandia National Laboratories
Authors: L. Zhang, Sandia National Laboratories
R.J. Shul, Sandia National Laboratories
G.A. Vawter, Sandia National Laboratories
C.G. Willison, Sandia National Laboratories
C.Y. Gao, Sandia National Laboratories
J. Han, Sandia National Laboratories
S.J. Pearton, University of Florida
Correspondent: Click to Email
With the rapid advance of III-N growth and processing technologies, GaN-based laser diodes (LDs) have been realized with continuously improved lasing thresholds and lifetimes. However, compared to their more mature arsenide and phosphide counterparts, the III-V nitride based LDs suffer from higher threshold current density and lower quantum efficiency. The reason for this is partly due to the lack of vertical profiles and sidewall roughness of the dry-etched laser facets in the III-V nitride structures, resulting in low mode reflectivity and high optical scattering loss. Therefore, it is essential to develop dry etch processes which yield anisotropic, smooth sidewalls. In this work, GaN etched sidewall profiles and morphologies are studied using an Inductively Coupled Plasma (ICP) reactor and will be compared to Reactive Ion Beam Etch (RIBE) results. Highly anisotropic profiles are expected in RIBE due to the acceleration of the ions through a series of grids located between the source and the sample as well as low pressure operation that reduces ion scattering. For BCl@sub 3@/Cl@sub 2@/Ar ICP chemistries, it was found that sidewall angles ranged from less than 70° to greater than 85° as a function of plasma chemistry, plasma density, ion energy, chamber pressure, and etch mask. The best ICP results were obtained using a photoresist mask, at 500 W ICP power, -150 V DC bias, 2 mTorr pressure, 32 sccm Cl@sub 2@, 8 sccm BCl@sub 3@, and 5 sccm Ar flow rate. Sandia is a multiprogram laboratory operated by Sandia Corporation, a Lockheed Martin Company, for the United States Department of Energy under contract DE-ACO4-94AL85000.