Effect of pre-deposited boron atoms on self-assembled growth of Ge islands on Si(100) substrate by UHV/CVD was investigated by atomic force microscopy (AFM). Proportion of dome-shaped Ge islands increases with the increasing of flux of B2H6. Quite uniform dome-shaped Ge quantum dots with size distribution of less than ±3%, which is narrower than the size distribution of typical bimodal self-assembled Ge dots, were obtained after appropriate boron pre-deposition. Based on the shape transition model we proposed before, the uniform size and shape distributions after boron pre-deposition were explained. The results show that boron pre-deposition can be used to fabricate uniform Ge quantum dots to meet the requirements of opto-electronic devices.
