| Rapid thermal process and selective emitter are promising techniques for fabricating solar cells in mass production, a screen printable paste is used in this process and can reduce the cost without any sacrifice to the performance of the cell. In this paper, we present a preparation method of this screen printable phosphorous diffusion source which is made by adding a polymer solution to the diffusion source and form a stable and transparent compound. This paste has many advantages, such as a wide range for the dopant concentration and decomposed completely when heated, it also has a relatively higher pH value as compared with the relevant product in foreign countries, etc. After diffusion both in the conventional furnace and the RTP furnace, we can draw the following conclusion: 1) The sheet resistance has excellent performance after different diffusion conditions in the two furnace;2) Both the dopant concentration in the phosphorous paste and the diffusion conditions have some influence on the surface concentration(Ns), and the junction depth is only influenced by the diffusion time in the conventional furnace; 3)It can achieve a high dopant concentration under the metal contacts areas after diffusion, and realize a appropriate junction depth and surface concentration to meet the essential needs for a selective emitter;4) between 850 C-925 C in RTP furnace, the junction depth show little relations with the process temperature; and have a direct ratio with the diffusion time;5) in the RTP process, the substrates are not suited for being placed on a material whose heat-absorb coefficient is not the same with the substrates;6) The phosphorous paste has excellent diffusion performance and are suited for fabricating selective emitter combined with RTP process.
|
PDF Full Text Request