Surface reconstruction in TGS family crystals under humidity and temperature controls

Abstract

 Surface reconstruction of TGS family single crystals has been investigated using AFM at ambient and controlled conditions. Domain boundary migration with simultaneous formation of holes at the boundary has been imaged for the first time. It is found that domain wall migration is accompanied by formation of elongated holes on originally negative end. Using humidity / temperature controlled AFM, holes on the positive end have been obtained with fast dehumidification while there is no such hole-formation with slow dehumidification. These observations provide direct evidences for a dissolution / recrystallization model accounting for hole / terrace formations. On the basis of this work, it is further proposed that the hole-formation upon the fast dehumidification can be ascribed by mass transfer limitation (kinetic control). On the contrary, with a slow dehumidification rate, the same crystal plane would resume a flatten termination to reduce the total surface energy (thermodynamic control).