Electrical characterization of GeSn grown on Si using ultra high vacuum chemical vapor deposition method

Recently, there has been considerable interest in growing Ge$_{1-x}$Sn$_{x}$ alloys on Si with x$<$ 0.2 for the purpose of developing optoelectronic devices that can be integrated with Si-based electronic technology. Here we report Hall coefficient and resistivity measurements as a function of temperature from thin epitaxial layers of GeSn grown on Si substrates using ultra high vacuum chemical vapor deposition. The Hall measurements show that GeSn samples with Sn concentrations of 1.5 and 2 {\%} are of high quality. The hole concentration for the boron doped Ge$_{0.98}$Sn$_{0.02}$ sample at room temperature is 7.1x10$^{18}$ cm$^{-3}$ while that of the as-grown undoped sample is 9.8x10$^{16}$ cm$^{-3}$. The measured hole mobility for Ge$_{0.98}$Sn$_{0.02}$ alloys with carrier concentrations greater than 10$^{18}$ cm$^{-3}$ are found to be comparable to those found in Ge samples with similar doping concentrations.