Electrical characterization studies of p-type Ge, Ge1−ySny, and Si0.09Ge0.882Sn0.028 grown on n-Si substrates

• Investigation of electrical properties of p-GeSn/n-Si as a function of temperature.
• Found evidence of a degenerate conducting layer near the interface of p-GeSn/n-Si.
• Found a conductivity type change of p-GeSn/n-Si from p to n at around 370–435 K.
• Observed lower mobility of p-GeSn/n-Si due to carrier scattering near interface.
• Detailed behavior of temperature-dependent electrical conductivity of p-GeSn/n-Si.

The electrical properties of p-type Ge, Ge1−ySny, and Si0.09Ge0.882Sn0.028 samples grown on n-type Si substrates using ultra-high vacuum chemical vapor deposition have been investigated as a function of temperature. Degenerate parallel conducting layers were found in all Ge/Si, Ge1−ySny/Si, and Si0.09Ge0.882Sn0.028/Si samples, which are believed to be associated with dislocation defects at the interface produced by the lattice mismatch between the two materials. These degenerate conducting layers affect the electrical properties of all the thin epitaxial films. Additionally, temperature dependent Hall-effect measurements show that these materials exhibit a conductivity type change from p to n at around 370–435 K. The mobilities of these samples are generally lower than that of bulk Ge due to carrier scattering near the interface between the epitaxial layer and the Si substrate and also due to alloy scattering. Detailed behavior of temperature-dependent conductivity of these samples is also discussed.