Reversible Phase Transitions In The Pseudomorphic Root 7x Root 3 >-Hex In Layer On Si(111)

Using scanning tunneling microscopy, reversible phase transitions have been detected in the modulated pseudomorphic In monolayer on the Si(111) surface. It has been found that the room-temperature quasihexagonal root 7x root 3 structure is transformed into the root 7x root 7 structure during cooling in the temperature range from 265 to 225 K. Further cooling results in developing long-range modulations in the In layer, including formation of the chevron-type structure with 6 root 7x root 7 periodicity, the ordered arrays with regular antiphase domain boundaries with local 3 root 7x root 7, and 2 root 7x root 7 periodicity and the chained-ring structure with 10/3 root 3x40/3 root 3 periodicity, which is believed to originate from the 5/3 root 3x5/3 root 3 structure occurring at room temperature near surface defects and at domain boundaries of the original root 7x root 3- In phase.