Ion implantation and SIMS profiling of impurities in II-VI materials (HgCdTe and CdTe)

Abstract

Ions from throughout the periodic table have been implanted into HgCdTe and CdTe under a variety of conditions, and the resulting atom depth distributions measured using oxygen and cesium secondary-ion mass spectrometry (SIMS). Many of these ions were implanted in the 〈110〉 crystal direction as well as in a random orientation close to 〈111〉. Most of the HgCdTe material implanted was solid-state-recrystallized bulk Hg1-xCdxTe (x = 0.19 to 0.35) thermally processed at 350°C for 3 or 4 weeks (device-quality material) and etched prior to implantation. Ions from H to Ta were implanted at energies from 100 to 700 keV and fluences from 1013 to 3x1015 cm-2. Both oxygen and cesium SIMS techniques were studied and developed. Many of the implanted elements were profiled using both oxygen and cesium SIMS. Implant profiles and determinations of range and range straggle versus atomic number (Z1) of the elements implanted in a random (111) orientation and in some cases, profile moments determined from a Pearson IV computer-fitting routine are illustrated. Profiles for 〈110〉 channeled implantations and the deeper channeled ranges and impurity densities achievable in the deep 〈110〉 channeled regions are shown. Determinations of the electronic stopping Se and its Z1-dependent nature (oscillations) are described in the channeling range as a function of Z1. The SIMS technology developed for this work is discussed. SIMS sensitivity factors for HgCdTe and CdTe are shown to be the same within experimental accuracy (relative to Te).