Temperature Effects On The Hydrogen Content And Passivation Of Silicon Surface Coated With Sio2 And Sin Films

C. U. Ike
2013 IOSR Journal of Engineering  
A detailed comparison of the passivation quality and its dependence on the low and high temperature anneals has been carried out for various promising Si surface passivation schemes. The passivation schemes investigated include; conventional furnace oxide (CFO) rapid thermal oxide (RTO), belt line oxide (BLO), plasma deposited oxide (PDO), SiN deposited by plasma enhanced chemical vapour deposition (PECVD). The passivated low resistivity (1Ω-cm) p-type silicon samples were subjected to three
more » ... bjected to three annealing treatments; 400 o C in forming gas (FGA), 730 o in air and 850 o C in air to stimulate heat-treatments which were typically used for contact anneal, font ohmic contacts, and back surface field formation respectively for screen printed silicon solar cells. It was found that the passivation quality of PDO, SiN, RTO and CFO single layers improved significantly after the 400 o C FGA and 730 o thermal cycles with RTO resulting in the lowest surface recombination velocities (S eff ) of 154 and 405 cm/s, respectively. Silicon wafers coated with belt oxide (BLO and BLO/SiN) did not show any improvement in (S eff ) which remained at 5000cm/s due to the inferior quality of BLO formed compressed air. The oxide/nitride stack passivation was found to be far superior to single-layer passivation resulting in (S eff ) of 70cm/s for the RTO/SiN scheme after the two high temperature anneals (850 and 730 o C). A combination of reduced hydrogen content and very low S eff in the RTO/SiN stack suggested that the release of hydrogen from SiN during the anneal further passivated the RTO/Si interface underneath.
doi:10.9790/3021-031034547 fatcat:h5ve2s47uvb3fh47vy4okebtsq