Detection of Sulfur‐Related Defects in Sulfur Diffused n‐ and p‐Type Si by DLTS. Issue 17 (4th June 2019) - Gwozdz, Katarzyna
Abstract : Sulfur is diffused into Czochralski (CZ) and Float‐Zone (FZ) silicon wafers at 1200 °C for 30 h. After diffusion, the wafers are slowly cooled in air. Several defect levels are observed by deep level transient spectroscopy (DLTS) in n‐ and p‐type samples. All defects levels are related to sulfur defects, but none could be identified with the donor and double donor states of substitutional S or molecular S2 . Additional annealing of the samples at 300 °C generates four DLTS levels in n‐type Si and no peaks in p‐type Si. The enhancement of the emission rate with the electrical field confirm their donor and double donor‐like behavior. The authors identify the four DLTS levels in the annealed n‐type Si samples with the different charge states of monoatomic S and molecular S2 (S 0, S +, S2 0, and S2 + ) defects in Si. Hydrogenation of the annealed samples by wet chemical etching results in a reduction of the intensity of S 0, S +, S2 0, and S2 + due to a passivation of these defects. The authors did not observe any electrically active SH‐complexes in the hydrogenated samples. Abstract : Sulfur doped Si samples show after diffusion several DLTS levels. Only an anneal at 300 °C generates the well‐known levels of the substitutional S and S2 donors. Some of the levels in the sample after diffusion coincide with the S and S2 levels but are shown to have different origins.