Influence of temperature on the crystal habit of silicon in the SiHCl CVD system I. Experimental results

The orientation dependence of silicon crystal growth in the near-equilibrium SiHCl system was studied as a function of temperature by the use of hemispherical single crystal substrates. All the experimentally observed faces and macroscopic steps belonged to one of the 〈110〉 zones, which demonstrates the stability of the nearest-neighbour periodic bond chains (PBCs). Dependent on the experimental conditions, several flat faces were observed that have not been reported before ({331},{551},{337} and {7713}), in addition to the faces that have been reported by several other authors ({111},{110},{113} and {001}). A division of the observed faces into {hkk}_h<k and {hhk}_h>k faces is made, which is based on a nearest-neighbour PBC analy sis. These two categories of faces behave differently as a function of temperature. At temperatures above ∼ 1340 K the {hhk}_h<k parts of the 〈110〉 zones contain flat faces, while below this temperature these faces disappear and only macroscopic steps are observed. On the other hand, faces with indices {hhk}_h<k were found to become less important or even disappear from the near-equilibrium growth form at higher temperatures.