Intrinsic Point Defect Clustering in Si: A Study by HVEM and HREM in Situ Electron Irradiation

The behaviour of intrinsic point defects in silicon is one of the most intricate problems in solid state physics. Since the concentration of the defects in thermal equilibrium is extremely small and below detection limit of most analytical tools, handling and testing properties have so far remained an uphill task. One way to circumvent this problem is the study of point defect reactions at non equilibrium conditions, for instance during intensive irradiation. Using this approach the configurations of a number of vacancy-related defects have been well established (for a review, see, for example [1]). There was much less experimental information concerning the self-interstitial-related defects in silicon for until recently. For the time being it is known that clustering of self-interstitial atoms in silicon leads to the formation of extended defects as a consequence of technologically important treatments such as thermal oxidation, long-time annealing, ion implantation and crystal growth. Depending on the temperature various defect types are known to occur in silicon after such treatments: i.e. dislocation-type defects at high temperature (800–1200°C), rod-like and {113} defects at intermediate temperature (300–800°C) and small clusters without pronounced habit planes at low temperature (−180 to 300°C) (see, for instance, the review of this topic in [2]). For most of the physical methods employed clustering phenomena make it difficult to investigate point defect behaviour due to the weak electrical activity clusters.