Raman and SIMS studies of rapid thermal annealing effect of silicon ion implanted GaAs Original Research Article

Raman studies were carried out on GaAs samples which were double implanted with Si and subjected to rapid thermal annealing (RTA) at temperatures of 900°C for 25 s (Sample-A), 925°C for 15 s (B) and 950°C for 6 s (C). In order to study the diffusion profiles of these implanted dopants, the dopant concentration vs depth of all the three samples were obtained by secondary ion mass spectrometry (SIMS) studies. From the Raman studies, it is observed that the LO phonon mode interacts with the plasmons resulting in L+ and L− phonon–plasmon modes in all the three samples. Further, from the peak value of these L+ and L− phonon–plasmon modes, the active carrier concentration in the samples using the plasmon frequency versus carrier concentration curve were found to be 4.49×1017, 7.06×1017 and 4.70×1017 cm−3, respectively. These values are compared with the dopant concentration as obtained from the SIMS depth analysis. It is observed that dopant concentration obtained through SIMS is higher than the carrier concentration obtained from Raman studies in samples A and B, but in sample C these concentrations are nearly the same. SIMS data further shows that the diffusion of Si is highest in sample C. Raman studies show that the carrier concentration is highest in sample B which agrees well with the concentration obtained from the Hall effect and electrical conductivity measurements.