Secondary ion mass spectrometry sensitivity factors versus ionization potential and electron affinity for many elements in HgCdTe and CdTe using oxygen and cesium ion beams

Abstract

We implanted ions of 45 elements into HgCdTe, and into CdTe in some cases, at a variety of energies and fluences, and successfully measured the resulting depth distributions for 43 of them using oxygen and cesium primary ion beams and positive and negative secondary ion mass spectrometry (SIMS), respectively. Relative sensitivity factors for SIMS were determined for these elements in HgCdTe and CdTe using the known implantation fluences. The SIMS relative sensitivity factor is proportional to the inverse of the relative ion yield. We have plotted the results from oxygen SIMS and positive ions versus ionization potential (I), and from cesium SIMS and negative ions versus electron affinity (A) of the implanted elements. These data can be used to test models and theories about the dependence of positive and negative ion yield on I and A. Many of the data from oxygen SIMS for elements with ionization potential between 5 and 10 eV are consistent with the model of positive ion yield dependence on exp(−I), but some elements differ reproducibly and consistently from that model. Elements with ionization potential less than 5 eV and greater than 10 eV follow different dependencies. The data from Cs SIMS tend to fit the model of negative ion yield proportional to exp(+A), but no consistent single curve can be drawn through the data. The data for CdTe agree with those for HgCdTe within experimental error.