Fabrication of GePb-Alloys by Means of Pulsed Laser Induced Epitaxy

Theoretical simulations predict that direct band transitions are favored in Germanium-Lead (GePb) alloys with Pb concentrations of $\text{c}_{\mathrm{Pb}} \approx 3.4\%$. This could enable the creation of semiconductor lasers that are directly structured on Ge substrates. However, the formation of alloys with these properties is hindered by the low equilibrium solubility of Pb in Ge. Therefore, the usage of out-of-equilibrium growth methods, such as pulsed laser induced epitaxy (PLIE), is necessary. The contribution focusses on the formation of GePb alloys with varying Pb concentrations. To cover a wide range of Pb concentrations, pulsed laser deposition (PLD) was utilized to deposit thin and smooth Pb films of varying thicknesses on Ge samples. After deposition, PLIE was used for alloying. For both processes, an Argonfluoride (ArF) excimer laser emitting radiation at a wavelength of $\lambda =193$ nm was used. The quality of the resulting alloys is evaluated by using Raman spectroscopy and the impact of different process parameters of PLIE is discussed.