The preparation of flat H-Si(111) surfaces in 40% NH4F revisited

The reasons why ideally flat H-Si(111) surface call be prepared by NH4F etching are investigated from correlation between AFM observations and experimental conditions used for etching. It is shown that pitting may be completely suppressed if a one side polished wafer is immersed in an oxygen free solution. An analytical electrochemical study of the (111) and rough face of the same n-Si wafer is presented to yield insight into observations. (C) 2000 Elsevier Science Ltd. All rights reserved.