REFLECTANCE ANISOTROPY AS AN IN-SITU MONITOR FOR THE GROWTH OF INP ON(001)INP BY PSEUDO-ATMOSPHERIC PRESSURE ATOMIC LAYER EPITAXY

Single wavelength reflectance anisotropy (RA) has been used to monitor the growth of InP onto (001) InP substrates in real time under atmosp heric pressure atomic layer epitaxy ''(ALE)-like'' conditions in which the In and P precursors were introduced sequentially into the reactor . The RA data indicates that at temperatures below 325 degrees C the i nitial interaction of TMI with surface P-dimers results in a change in anisotropy and that the resulting surface is unreactive towards phosp hine or additional TMI possibly as a result of a residual species of t he type In(CH3)(x) where x = 1-3 acting as a site blocker or preventin g In dimer formation. At higher temperatures, the RA data indicates th at for InP growth on (001) InP using phosphine and trimethylindium (TM I) the onset of growth occurs between 300-325 degrees C. This observat ion is implied directly from the appearance of the recovery portion of the RA transient which indicates that the second half of the ALE-like cycle restores the surface to the starting P-stabilised conditions. T his low temperature for the onset of growth as compared to conventiona l InP MOCVD is attributed to the operation of a surface catalysed reac tion of both phosphine and TMI.