Context: A new style of wafers composed of gallium-nitride-on-silicon (GaN-on-Si) is being used to produce white LEDs using 200-mm silicon wafers. This avoids the typical costly sapphire substrate in relatively small 100- or 150-mm wafer sizes. The sapphire apparatus must be coupled with a mirror-like collector to reflect light that would otherwise be wasted. It is predicted that by 2020, 40% of all GaN LEDs will be made with GaN-on-Si. Manufacturing large sapphire material is difficult, while large silicon material is cheaper and more abundant. LED companies shifting from using sapphire to silicon should be a minimal investment.

Question: What is being used to produce white LEDs?
Answer: wafers composed of gallium-nitride-on-silicon

Question: What size are the wafers used to create white LEDs?
Answer: 200-mm

Question: By using silicon wafers, what is being avoided?
Answer: costly sapphire substrate

Question: What needs to be used to reflect light that would otherwise be wasted?
Answer: mirror-like collector

Question: By what year will% of all GaN LEDs be made with gallium-nitride-on-silicon wafers?
Answer: 2020

Question:  What is being used to produce white non-LEDs?
Answer: Unanswerable

Question:  What size are the wafers used to create red LEDs?
Answer: Unanswerable

Question:  By using silicon wafers, what is not being avoided?
Answer: Unanswerable

Question: What needs to not be used to reflect light that would otherwise be wasted?
Answer: Unanswerable