Sixtron Silexium™ films have been demonstrated to provide an effective solution for anti-reflection and passivation coatings for high-performance mono-crystalline boron doped p-type Cz (Czochralski) silicon solar cells without the use of dangerous silane gas.
Under the proper process conditions, Silexium films can provide the following key benefits:
- Comparable end-of-line cell efficiency of SiH4-free SiCxNy to pyrophoric SiNx for front-side n+ emitter passivation and ARC (anti-reflection coating)
- Significantly less Light Induced Degradation (LID) with excellent stability
- Higher shunt resistance
- Lower reverse leakage current
- Rear-side p-type silicon surface passivation: PECVD SiO2/SiCxNy stack has better cell efficiency than PECVD SiO2/SiNx stack for PERC-type cell
- Flexibility of various passivation coatings from a single source; SiC, SiCN, SiCO, SiCON etc, for both front-side and rear-side passivation
The precursor for Silexium films is delivered to industry standard plasma enhanced chemical vapor deposition (PECVD) equipment by Sixtron's SunBox silane-free gas generation system. The SunBox system was awarded the Cell Award for Best Process Technology for c-Si Solar Cell Manufacturing at the 2009 Intersolar show in Munich, Germany.
LID - Background
Solar cells fabricated with boron doped p-type Cz wafers suffer from performance degradation when exposed to light illumination. They become 3 to 5 % (rel.) less efficient when first exposed to the sun. Within hours, small amounts of oxygen in boron-doped monocrystalline solar cells (resulting in B-O complex) react with sunlight to decrease the solar cell's output efficiency.
Silexium™ films have been demonstrated to effectively passivate these boron-oxygen (B-O) complexes which are responsible for LID under illumination. In this way, LID can be significantly reduced to less than 2 % rel., typically 1% rel., thereby increasing stabilized (post-LID) solar cell efficiency.
Dr. Junegie Hong, CTO of Sixtron, discovered that Silexium coated boron-dope Cz cells degrade much less than conventional silicon nitride coated Cz Cells during the first several hours of illumination, which depends on the nature of Cz wafers, namely oxygen and boron content.