Boron-doping induced Sn loss in GeSn alloys grown by chemical vapor deposition

Although the Sn content in GeSn can reach 10% using chemical vapor deposition, the reduction of Sn content by in-situ boron doping and solid phase doping by chemical vapor deposition are observed. The Sn loss increases with the increasing boron concentration in GeSn:B alloys, while there is no Sn reduction at the similar phosphorus doping level in GeSn:P. Based on the first principle calculations, the energy for boron to place Sn in GeSn is lower than that for boron to place Ge, indicating that boron atoms prefer to occupy Sn sites. The Sn loss is more serious for boron-implanted GeSn with thermal annealing at 400 °C than in-situ boron-doped GeSn even with 500 °C thermal annealing.