SIMS profiling of GaAs/δ-AlAs/GaAs/… heterostructures using polyatomic ionized oxygen clusters

Abstract

We have studied the possibility of using polyatomic ions as the primary projectile particles for the depth profiling of solid heterostructures by means of secondary ion mass spectrometry (SIMS) in combination with ion etching. Bombardment of a target by ionized oxygen clusters of the On+ (n=3, 4) type allows the specific impact energy per primary atom to be reduced, which significantly improves the depth resolution. It is shown that a beam of primary On+ (n=3, 4) clusters with the specific impact energy as low as 1 keV per oxygen atom can be obtained using a standard ion source with a magnetic mass separator. High-resolution depth profiles of a test heterostructure of the GaAs/δ-AlAs/GaAs/… type were obtained using a magnetic sector mass spectrometer and a primary beam of O3+ ions with a specific energy of 1 keV per oxygen atom. The experimental data are compared with the results of computer simulation of the ion sputtering process performed using the DITRIRS code.