Surface conductance of Si(100)2 x 1 and Si(111)7 x 7

The surface conductance of Si(1 0 0)2 x 1 and Si(1 1 1)7 x 7 was measured a s a function of temperature on a fully-depleted Si/SiO2/Si substrate. The s urface conductance of Si(1 0 0)2 x 1 shows a clear signature of the c(4 x 2 ) --> 2 x 1 order-disorder surface phase transition near 200 K. The surface conductance of Si(1 1 1)7 x 7 increases dramatically after passivation wit h molecular oxygen. This phenomenon is not yet understood. (C) 2001 Elsevie r Science B.V. All rights reserved.