AVS 50th International Symposium
    Semiconductors Tuesday Sessions
       Session SC-TuA

Paper SC-TuA6
Reflectance Interferometry During III-V Nitride Growth, Much More than a Growth Rate Monitor

Tuesday, November 4, 2003, 3:40 pm, Room 321/322

Session: Compound Semiconductor Growth and Processing
Presenter: C.R. Eddy, Jr., Naval Research Laboratory
Authors: C.R. Eddy, Jr., Naval Research Laboratory
R.T. Holm, Naval Research Laboratory
R.L. Henry, Naval Research Laboratory
J.C. Culbertson, Naval Research Laboratory
Correspondent: Click to Email
The application of laser interferometry to the monitoring of wide bandgap semiconductor nitride growth has expanded considerably in recent years. At present, a rapidly growing number of III-V nitride growth systems, MBE and MOCVD alike, employ some version of the technique to monitor growth rates. But growth rate monitoring makes use of a small subset of the useful information the technique affords. In this paper, we discuss the application and interpretation of laser interferometry in the MOCVD growth of gallium nitride and aluminum gallium nitride thin films that employ AlN nucleation layers. We employ a 543.5 nm HeNe laser, lock-in amplifier, and ratiometer (to normalize out laser fluctuations) to monitor growth in a simple vertical tube reactor that is rf heated. In this application, the technique has proven useful as a monitor of not only the thickness, but also the quality of the material grown. Further, the technique can help identify drifts in the process from run to run and within a given run. We will comment on the usefulness of the technique in monitoring surface and interface roughness, film stoichiometry (for ternaries) and thickness uniformity. Finally, we will highlight specific examples where the technique has proven useful in troubleshooting growth irregularities.