CHANNELING CHARGED-PARTICLE ACTIVATION-ANALYSIS OF LIGHT IMPURITIES AT TRACE LEVELS IN GAAS

Light element trace concentrations of boron, carbon and oxygen in the range of 10 to 150 ppba were localized in monocrystalline, as-grown Ga As by combining the channeling technique with the sensitivity of charg ed particle activation analysis (CPAA). The experimental data were eva luated using stopping power and ion flux distributions in the crystal channels that were simulated with the Monte Carlo program MABIC (mater ials analysis by ion channeling) [1]. Si samples have been used as a r eference material. The B and O concentrations of the Si samples are in the range of 100 ppma and 8 to 40 ppma respectively. In GaAs trace co ncentrations of boron, carbon and oxygen were found to be located pref erentially in an interstitial position. In Si boron was localized main ly on substitutional sites for concentrations in the 100 ppma range. O xygen concentrations of 8 to 40 ppma in Si were determined to be domin antly incorporated on interstitial positions.