HOMOEPITAXY OF SILICON AT LOW-TEMPERATURE ON CLEAN AND GA-COVERED SUBSTRATES

We present a high resolution transmission electron microscopy (HRTEM) and reflection high energy electron diffraction (RHEED) study of the m olecular beam homoepitaxy of Si(111) with and without Ga as surfactant . Cross-sectional images show that the growth at low temperature was a ssociated with a periodic stacking fault (ABC/BCA fault type), leading to a high surface roughness. If the Si film was grown with 1/3 monola yer of Ga added prior to the growth, cross-sectional images show a per fectly flat surface, even at growth temperatures as low as 300 degrees C. According to a systematic study of the damping of the RHEED oscill ations during the growth with and without Ga and the determination of the 2D nucleation/step-flow transition, no obvious kinetic effect coul d be attributed to the surfactant action. (C) 1997 Elsevier Science S. A.