RHEED Study of the Si(100) Surface Structure with Temperature

Abstract

The structural properties of clean silicon (100) surface have been investigated by RHEED. The clean surface is reconstructed and the RHEED pattern shows superstructures associated to (2×1) and (1×2) domains. We recorded the intensity of the integer, as well as half order rods of the RHEED pattern, as a function of the crystal temperature from room temperature to 1500 K. The (1×2) domain grows at the expense of the others until it predominates. Between 1170 K and 1350 K the RHEED intensity of half order spots varies quickly and passes through a maximum. Such a behavior could be interpreted as originating from step bunching due to the heating mode (Joule effect by using DC current). At around 1350 K the half order spot decreases abruptly. The analysis of the intensity profile change versus temperature shows that the half width increases as the intensity decreases until the spot disappears. Analysis suggests that at arround 1400 K there is a lack of order at the crystal surface, which could originate in an incomplete melting.