| Abstract
| - The detection of high-mass, nonstoichiometric, GaxAsyand InxPy secondary ion clusters using time-of-flightsecondary ion mass spectrometry is reported for the firsttime. The GaxAsy and InxPy clusters are detected in bothpositive and negative ion spectra and extend to massesof at least 6000 dalton (Da). Consecutive clusters differby the addition of one gallium (indium) atom. This leadsto nonstoichiometric clusters at high mass (i.e., Ga15As3at 1270 Da) which are metastable above a critical mass.The relative secondary ion yields of high-mass GaxAsyclusters detected using several primary ion sources (Cs+,Bi+, Bi3+, Bi32+, Bi52+, C60+, and C602+) are compared.The relative secondary ion yield of high-mass GaxAsyclusters is significantly enhanced by the use of clusterprimary ions and the best relative secondary ion yield isobtained using Bi3+ primary ions. An application of thehigh-mass GaxAsy clusters is presented, in which theseclusters are utilized to distinguish between contaminantlevels of Ga and bulk GaAs structure in a depth profile ofa MnAs/GaAs heterojunction. These results illustrateimproved analysis of inorganic materials using clusterprimary ions and break the paradigm of stoichiometricsecondary cluster ion formation for SIMS of inorganiccompounds.
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