High sensitivity analysis of atmospheric gas elements

We have investigated the detection limit of H, C and O in Si, GaAs and InP using a Cameca IMS-4f instrument equipped with a modified vacuum system to improve the detection limit with a lower sputtering rate We found that the detection limits for H, O and C are improved by employing a primary ion bombardment before the analysis. Background levels of 1 1017 atoms/cm3 for H, of 3 1016 atoms/cm3 for C and of 2 1016 atoms/cm3 for O could be achieved in silicon with a sputtering rate of 2 nm/s after a primary ion bombardment for 160 h.We also found that the use of a 20 K He cryo-panel near the sample holder was effective for obtaining better detection limits in a shorter time, although the final detection limits using the panel are identical to those achieved without it.