Surface roughening of undoped and in situ B-doped SiGe epitaxial layers deposited by using reduced pressure chemical vapor deposition

• Published in: Journal of the Korean Physical Society Vol. 72; no. 1; pp. 101 - 106
• Main Authors: Kim, Youngmo, Park, Jiwoo, Sohn, Hyunchul
• Format: Journal Article
• Language: English
• Published: Seoul The Korean Physical Society 01.01.2018; Springer Nature B.V; 한국물리학회
• Subjects: Boron; Chemical vapor deposition; Epitaxial growth; Epitaxial layers; Flow velocity; Mathematical and Computational Physics; Particle and Nuclear Physics; Physics; Physics and Astronomy; Roughening; Silicon germanides; Surface roughness; Theoretical; 물리학; Residual strain; Surface roughness; Surface roughening; Boron doping; Silicon-germanium (SiGe)
• ISSN: 0374-4884; 1976-8524
• DOI: 10.3938/jkps.72.101

Si 1− x Ge x (:B) epitaxial layers were deposited by using reduced pressure chemical vapor deposition with SiH 4 , GeH 4 , and B 2 H 6 source gases, and the dependences of the surface roughness of undoped Si 1− x Ge x on the GeH 4 flow rate and of Si 1− x Ge x :B on the B 2 H 6 flow rate were investigated. The root-mean-square (RMS) roughness value of the undoped Si 1− x Ge x at constant thickness increased gradually with increasing Ge composition, resulting from an increase in the amplitude of the wavy surface before defect formation. At higher Ge compositions, the residual strain in Si 1− x Ge x significantly decreased through the formation of defects along with an abrupt increase in the RMS roughness. The variation of the surface roughness of Si 1− x Ge x :B depended on the boron (B) concentration. At low B concentrations, the RMS roughness of Si 1− x Ge x remained constant regardless of Ge composition, which is similar to that of undoped Si 1− x Ge x . However, at high B concentrations, the RMS roughness of Si 1− x Ge x :B increased greatly due to B islanding. In addition, at very high B concentrations (~ 9.9 at%), the RMS roughness of Si 1− x Ge x :B decreased due to non-epitaxial growth.