5.4. Selective emitter structure
Selective emitter structure is mainly used in screen printing technology which has a great impact on recent development and is a very simple technology. This technology has a lightly doped emitter because if we heavily dope the top surface then the surface gets damaged. Selective emitter technology is younger technology and is widely used in screen printing. Selective emitter simply means heavy doping directly on metal with low contact resistance, which has problem over lightly doped emitter where the light penetrates [61] and [62]. Now, the rear surface passivation is also used to increase the efficiency with combination as AlOx/SiNx, SiO2/SiNx, and SiOxNy.