PROGRESS IN NONCONTRACT DYNAMIC FORCE MICROSCOPY

The technique of operating the scanning force microscope in the dynami c noncontact mode (dynamic force microscopy) has been improved. Home-b uilt instruments based on an optical beam deflection scheme in two dif ferent environments were used. The two force microscopes were operated in ambient air and in ultrahigh vacuum, respectively. In order to con trol the oscillating cantilever different methods were applied: slope- detection (lock-in amplifier, RMS-to-DC converter) and frequency modul ation (FM) technique as well. The advantages of this nondestructive te chnique are demonstrated on different samples, such as soft organic ma tter (hexagonally packed intermediate layer, Langmuir-Blodgett film), layer-structured compounds (CdI2), n-doped Si(111), and ferroelectric crystals [triglycine sulfate (TGS), guanidinium aluminum sulfate hexah ydrate (GASH)]. On TGS and GASH cleavage faces, the ferroelectric doma ins and domain walls could be imaged. From experimental data a spatial resolution of about 1-2 nm in lateral and <0.1 nm in vertical directi ons could be determined.