Dark current-voltage (Dark IV) measurement was done on diode samples with metal contacts that were evaporated on both sides of the wafer. The sheet resistances of the samples were measured using a 4-point probe, the doping concentration profile was measured using secondary ion mass spectrometry (SIMS), and the implied at 1-sun (using the minority carrier lifetime) was measured using quasi-steady-state photoconductance (QSSPC).

The samples were annealed at 950вЊ, 1000вЊ, and 1050вЊ with varying time with 30, 60, and 90вЂ‰min. Boron ions were implanted with an acceleration voltage of 40вЂ‰keV and a dose of 5 e15вЂ‰cm в€’2 on n-type c-Si wafers 675 Ојm thick and a resistivity of 4~7вЂ‰О© Phosphorus ions were implanted with an acceleration voltage of 30вЂ‰keV and a dose of 1 e15вЂ‰cm в€’2 on p-type c-Si wafers 675 Ојm thick and a resistivity of 8~12вЂ‰О© P-type and n-type wafers were implanted with phosphorus and boron, respectively, for emitter formation and were annealed subsequently to see the effect of the deep junction annealing. Lowering of the peak concentration should decrease the surface recombination, increasing the as well as the quantum efficiency at short wavelengths. Since the total concentration of the dopants is fixed for implanted emitters, high-temperature or long-time annealing lowers the peak concentration at the surface as well as increasing the deep junctions. In this study, however, the ion-implanted emitters were annealed even after they were activated to create deep junctions. The annealing was done at the least after the ions were activated in other studies to form a shallow emitter, which is thought to increase the due to their higher quantum efficiency at short wavelengths. The previous studies have created solar cells with minimum annealing. The activation part of the annealing is more critical since the in-activated dopants act as recombination sites, reducing the minority carrier lifetime and decreasing the of solar cells. The annealing condition has a major effect on ion-implanted solar cells because they control the activation and the diffusion profile of the ion-implanted dopants. This thermal process also activates the dopant ions by establishing them on substitutional sites where they are able to contribute holes (electrons) to the valence (conduction) band. This damage requires repairing, which is done by performing a postimplant thermal process.

These defects are in the form of Si self-interstitials, created when the ions collide with the Si atoms which then are displaced from their equilibrium positions. Дuring implantation the implanted dopants are bombarded into the silicon, and this process produces point defects within the lattice. The doping profile can be controlled by modifying the dose or the acceleration during the implantation or by modifying the annealing step, which also acts as a drive-in step. Compared to the thermal diffusion method, ion implantation also allows an excellent control over the doping profile. It does not require the etching of the phosphosilicate glass formed during the diffusion process or the additional edge isolation step. Of these methods, ion implantation, when applied to the solar cell fabrication, has many advantages compared to the conventional thermal diffusion method. There are many ways in creating the emitter, including the standard diffusion process, ion implantation, and epitaxial growth. The emitter is usually formed by diffusing the dopant atom into a silicon wafer surface. The formation of the emitter in fabricating solar cells is one of the critical processes in the solar cell fabrication process. PC1D simulation based on these results shows that, for p-type implanted solar cells, increasing the annealing temperature and time abruptly decreases the efficiency ( %), while, for n-type implanted solar cells, deep junction annealing increases the efficiency and, especially ( %) for backside emitter solar cells. This is due to the abrupt decrease in the bulk lifetime of the p-type wafer itself from 178 Ојs to 14 Ојs. However, for phosphorus emitters the implied decreases from 622вЂ‰mV to 560вЂ‰mV and the increases with deep junction annealing. QSSPC measurements show that the implied of boron emitters increases about 15вЂ‰mV and the decreases by deep junction annealing even after the activation due to the reduced recombination in the emitter. Boron emitters were activated at or higher, while phosphorus emitters were activated at.

P-type and n-type wafers were implanted with phosphorus and boron, respectively, for emitter formation and were annealed subsequently at 950 ~1050 for 30 ~90вЂ‰min for activation.

Pc1d change mobility