Donald A. Gajewski,* Jonathan E. Guyer,* Nhan V. Nguyen, and Joseph G. Pellegrino
National Institute of Standards and Technology, Gaithersburg, MD 20899-8121
In this poster, we present the optical response of thin film compound semiconductors measured using in situ spectroscopic ellipsometry (SE), at growth temperatures ((180 600) °C), during the growth by molecular beam epitaxy (MBE). We will focus on in situ SE results on low-temperature-grown GaAs (LT-GaAs or GaAs1+d) and InxGa1-xAs thin films on GaAs, which have applications in high-speed electronics devices such as ultra-fast (< 1 ps) photo-detectors and (> 1 GHz) transistors (pHEMTs), respectively. We have used in situ SE to construct a reference optical response library ((1.5 - 3.0) eV) for LT-GaAs and InxGa1-xAs as a function of temperature and composition. This optical response library in turn enables precise, real-time monitor and control of the composition, thickness, and structural properties during the MBE growth. We also correlate the in-situ-SE-measured optical response with other in situ and ex situ metrology such as reflection-high-energy electron diffraction (RHEED), diffuse reflectance spectrocscopy (DRS), and x-ray diffraction. This research is a part of the Semiconductor Electronics Division (SED)'s Metrology for Compound Semiconductor Manufacturing Project to develop new and existing in situ and ex situ materials growth monitoring tools, methodologies, and data to help the wireless and digital electronics industry to manufacture compound semiconductor devices more efficiently.
*National Research Council Postdoctoral Research Associate
Semiconductor Electronics Division, Electronics and Electrical Engineering Laboratory (EEEL), Technology Administration, U.S. Department of Commerce