Size-controlled Si quantum dots embedded in B-doped SiNx/Si3N4 superlatice for Si quantum dot solar cells

Under the condition of the fixed Si3N4 layer thickness of 1.1 nm, Si-QDs embedded in B-doped SiNx/Si3N4 multilayer thin films with various SiNx layer thickness were fabricated respectively. Si-QDs with controllable and nearly uniform size were formed in SiNx layers, and found that the optical band gap of the films can be adjusted by changing the thickness of SiNx layer. On the basis of this, the Si-QDs/c-Si heterojunction solar cells were prepared. It is found that the larger the band gap is, the higher the cell efficiency is. The best performance device is obtained with average QD size of similar to 3.5 nm, which has the highest efficiency of 7.05 % compared with the other two devices. This difference is caused by the difference of the spectral response of these devices.