Some LED makers have turned to GaN-on-Si LED technology over recent years to reduce manufacturing costs, since silicon substrates are cheaper compared to sapphire. Leading LED lighting manufacturers turning to alternative substrates include Soraa with its GaN-on-GaN technology, and GaN-on-Si manufacturers.
Theoretically, silicon wafers are cheaper than sapphire and projected to help manufacturers save 1 cent/mm2. Silicon have a much larger size of above 200 mm, sapphires at most measure 150 mm, while the largest GaN wafer is only 50 mm.
In addition, for every 15% lower EPI efficacy in silicon, about double EPI area is required compared to sapphire to meet the same lm/W. In reality, GaN-on-Si LEDs have a 10% performance gap, and in general a 66% higher EPI than sapphire.