Development and control of MOVPE growth processes for devices using reflectance anisotropy spectroscopy and normalized reflectance

摘要

The use of the optical in situ techniques reflectance anisotropy (RA) and normalized reflectance (NR) for metal-organic vapour-phase epitaxy (MOVPE) growth processes of compound semiconductor devices is reviewed. The RA signal detects small deviations in the doping profile during growth of hetero-bipolar transistors and correlates to the emission wavelength of edge-emitting laser structure via its sensitivity to the quantum well composition. The NR signal is crucial for the alignment of distributed Bragg reflectors (DBR) in vertical-cavity surface-emitting lasers. With simultaneously performed RA and NR measurements the doping profile as well as the DBR alignment can be determined in situ. The composition monitoring in quaternary InGaAsP grown on InP is demonstrated using the RA signal for the As: P ratio while the NR signal is used for the Ga: In ratio. For AlGalnP on GaAs the NR signal is sensitive to both the aluminium and the indium content. Therefore these effects have to be separated via the determination of the growth efficiency of the respective materials using the growth rate calculated from the NR signal.