Reduction of Threading Dislocation Density in Sputtered Ge/Si(100) Epitaxial Films by Continuous-Wave Diode Laser-Induced Recrystallization

We have developed a cost-effective, up-scalable, and high-throughput method combining continuous-wave (CW) diode laser and magnetron sputtering for fabricating low-defect single-crystalline Ge films for high-efficiency III–V solar cell applications. CW diode laser-induced recrystallization is demonstrated to dramatically reduce the threading dislocation density (TDD) of sputter-deposited single-crystalline Ge/Si epitaxial films by more than 3 orders of magnitude. This might be due to the change of growth mechanism from initial Ge/Si heteroepitaxy in the sputtering process to Ge/Ge homoepitaxy by the laser-induced lateral recrystallization process, overcoming the typical issue of Ge/Si lattice mismatch to achieve low TDD.