SURFACE ROUGHENING DURING DEPTH PROFILING BY SECONDARY ION MASS-SPECTROMETRY (SIMS) IN GAALAS AND GAAS

During bombardment of Ga1-xAlxAs and GaAs with oxygen we found an abrupt transition to higher sputter rates, change of the useful yield and significant increase of surface roughness at a well defined depth, which is essentially deeper than the penetration depth of the primary ions. Using oxygen and cesium as primary ions 'varying' energy and angle of incidence, residual gas pressure and matrix composition their effects on the phenomena were investigated. Although some remarkable properties of the sample modification process could be found, no theoretical description can be given up to now.