In Situ Optical Characterization And Control Of Epitaxial Iii V Crystal Growth

Device designers are placing new demands on crystal growers by requesting increasingly complex structures with more stringent constraints on composition, layer thickness and interface abruptness. Post growth analysis is no longer sufficient to meet these constraints and efforts are now underway to develop real lime methods of monitoring and controlling crystal growth. A number of diagnostic techniques are available for studying semiconductor surfaces during the growth process. Optical methods are preferred because they may be used at atmospheric pressure, in any transparent medium, and the photon flux is low so that the growth process is riot disturbed. However, optical techniques have a limited spectral range, and low surface sensitivity. Fortunately, the 1.5 to 6 eV energy range of quartz-optics systems contains most of the bonding-antibonding transitions for materials used in the growth of III-V semiconductors.