The Si(111)‐7×7 area surrounded by the Si(111)‐&sqrt;3×&sqrt;3R30°‐Ga region has been observed by scanning tunneling microscopy during the thermal desorption of Ga atoms at ∼600 °C and after the desorption. The 7×7 area exhibits triangular and strip patterns on the nanometer scale for the Si(111) substrates tilting toward the [112¯] and [1¯1¯2] directions, respectively. This is because faulted halves of the 7×7 reconstruction are adjacent to the &sqrt;3×&sqrt;3‐Ga area on the boundary between the 7×7 and &sqrt;3×&sqrt;3‐Ga areas during Ga desorption. It has been found that strip patterns with nanometer‐scale precision are formed on the Si(111) substrates tilting toward the [1¯1¯2] direction. ©1996 American Institute of Physics.