Answer
Semiconductors are the primary focus of Hiroshi Amano's research. Semiconductors are materials with electrical conductivity that falls between conductors and insulators. They are essential components in various electronic devices, including transistors, solar cells, and light-emitting diodes (LEDs). Amano's research has significantly contributed to the development of high-quality semiconductors, particularly gallium nitride (GaN), which is used in high-power and high-frequency electronic devices.