Formation of the Sputtered Phase of PbTe Crystals by Ar+ Plasma and Re-deposition of the Sputtered Species at Secondary Neutral Mass Spectrometry Conditions

Formation of the Pb and Te sputtered phase under exposure of the lateral surface of PbTe crystals grown from melt by the Bridgman method by Ar+ plasma at Secondary Neutral Mass Spectrometry (SNMS) conditions and re-deposition of the sputtered species on the sputtering crystal surface are investigated. Experimental evidence of mutual influence of the sputtering and re-deposition processes on each other during prolonged depth profiling of PbTe crystals is presented. Sputtering of the PbTe crystal surface forms the strongly supersaturated sputtered phase of Pb and Te. Re-deposition of the Pb and Te sputtered atoms on the crystal surface results in oscillations of sputtering rate of PbTe crystal and changes of average intensity of Pb and Te sputtering over sputtering time. A possible role of both the sub-critical nuclei of newly re-deposited phase and the re-deposited surface structures of post-critical sizes in generation of the features of PbTe crystal sputtering is discussed. It is concluded that formation and re-sputtering of the sub-critical nuclei of re-deposited phase leads to the oscillations of sputter yields of Pb and Te. Growth and re-sputtering of the re-deposited surface structures of post-critical sizes lead to changes of average values of Pb and Te sputter yields.