ONLINE GROWTH MONITORING OF INP-BASED DEVICE STRUCTURES BY REFLECTANCE ANISOTROPY SPECTROSCOPY

Reflectance anisotropy spectroscopy (RAS) has been used to study the m etalorganic vapor phase epitaxy growth process for GaxIn1-xAsyP1-y/InP light emitting diodes. The sensitivity of RAS to morphology changes i s demonstrated by InP growth on different InP:Fe substrates. RAS revea ls not only development of dull surfaces but also detects initial temp orary roughness of mirror-like layers. Based on the RAS results the su bstrate preparation was optimized, RAS spectra measured on n- and p-ty pe InP and p-type GaInAsP during light emitting diodes production are suitable for finger-printing of the growth process. Spectra from InP:S i and InP:Zn layers show characteristic features near 4.3 eV which all ow for assessment of doping level at growth temperature (640 degrees C ). Correlation of RAS spectra and transients during growth with the? q uaternary composition was achieved. A change in composition of only De lta x = 0.01, Delta y = 0.03 corresponding to a shift of photoluminesc ence-peak position by 16 nm was detectable in RAS spectra. The results demonstrate the high sensitivity and thus the suitability of RAS for online control during growth of device structures.