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

Raman studies were carried out on GaAs samples which were double implanted with Si and subjected to rapid thermal annealing (RTA) at temperatures of 9 00 degreesC for 25 s (Sample-A), 925 degreesC for 15 s (B) and 950 degreesC for 6 s (C). In order to study the diffusion profiles of these implanted d opants, the dopant concentration vs depth of all the three samples were obt ained by secondary ion mass spectrometry (SIMS) studies. From the Raman stu dies, it is observed that the LO phonon mode interacts with the plasmons re sulting 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 c arrier concentration in the samples using the plasmon frequency versus carr ier concentration curve were found to be 4.49 x 10(17), 7.06 x 10(17) and 4 .70 x 10(17) cm(-3), respectively. These values are compared with the dopan t concentration as obtained from the SIMS depth analysis. It is observed th at dopant concentration obtained through SIMS is higher than the carrier co ncentration 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 carrie r concentration is highest in sample B which agrees well with the concentra tion obtained from the Hall effect and electrical conductivity measurements . (C) 2000 Elsevier Science Ltd. All rights reserved.