Why were blue LEDs considered impossible?
The main obstacle was achieving efficient light emission from wide-bandgap semiconductors like gallium nitride (GaN). Specifically, making it p-type conductive was extremely difficult. The atomic structure of GaN tends to have a high dislocation density, which acts as a trap for charge carriers, severely reducing the quantum efficiency of light emission. Textbooks and prevailing theories suggested these materials were too prone to defects to be useful for optoelectronics. People said it was impossible, but I knew it would work if the right growth conditions and material quality could be achieved.
Ask Shuji Nakamura the follow-up →