IN-SITU THICKNESS MEASUREMENTS IN MOLECULAR-BEAM EPITAXY USING ALPHA-PARTICLE ENERGY-LOSS

The alpha-particIe energy loss method has been implemented in situ to monitor film thickness during growth by molecular beam epitaxy. For In P and GaAs substrates dosed with 500-1500 Bq of alpha-particIe emitter s, we have been able to measure thickness in situ of deposited GaAs an d InP, to an accuracy of 6 nm in 180 s of counting time. The correspon ding growth rate accuracy for growth rates on the order of 0.3 nm/s wa s +/-0.01 nm/s. The accuracy and counting time improvements expected w ith the use of a stronger marking source are also discussed. (C) 1997 Elsevier Science S.A.