Single-crystalline GePb alloys formed by rapid thermal annealing-induced epitaxy

Single-crystalline GePb alloys have been successfully achieved by implanting Pb into Ge, followed by rapid thermal annealing under N-2 atmosphere. The high crystallinity and the thickness of around 20 nm of the GePb alloys was determined by high-resolution x-ray diffraction and high-resolution transmission electron microscopy. The root-mean-square value of the as-implanted GePb sample is evaluated to be 1.25 nm in the 5 x 5 um scan area, which indicates a rather smooth surface. After being annealed at 400 degrees C, the result of a selected area electron diffraction pattern suggested that a single-crystalline alloy film was formed for the first time. The Pb composition of this sample is approximately 0.23% according to the x-ray photoelectron spectroscopy results. This value corresponds with the measurement result of the secondary ion mass spectroscopy. In addition, mobility enhancement in GePb/Ge samples has been identified by temperature-dependent Hall measurement, which indicates GePb alloys have great potential to be a promising high-mobility channel material for future monolithic optoelectronics integration application.