Electrical and structural characterization of boron-doped Si1−xGex strained layers

Abstract

The electrical activity and structural properties of rapid thermal chemical vapor deposition grown, boron-doped, strained Si1−xGex layers were investigated for different Ge content and doping levels. Strain measurements were obtained by Rutherford backscattering experiments and show good correlation between the mismatch strain and Ge content. Differential Hall effect profiling, secondary ion mass spectroscopy, and spreading resistance profiling were used to study the electrical doping activity of boron in the strained alloy and were directly compared in this investigation for the first time. It is shown that high electrical efficiency can be achieved in the grown material with boron concentration in the range of 1019–1020 cm−3. Nuclear reaction channeling experiments performed on the doped material were used to correlate the electrical behavior of the layers with structural incorporation of the dopants in the strained film. It was found that most of the dopant atoms occupy lattice sites in the strained alloy. Lower limits on the dopant solubility for the growth conditions are also reported.