Surface segregation of arsenic and phosphorus from buried layers during Si molecular beam epitaxy

Abstract

Unintentional doping of silicon films grown on heavily doped buried layers of arsenic and phosphorus during silicon molecular beam epitaxy has been studied by spreading resistance profiling and x-ray photoelectron spectroscopy. The measurements indicate that dopant surface segregation during growth is responsible for the unintentional doping. The segregation phenomenon has been characterized over a growth temperature range of 450–750 °C. The growth on heavily doped buried layers has implications for device applications such as Si/SiGe heterojunction bipolar transistors. Epitaxial processes to circumvent this effect and create abrupt doping profiles are explored.