> China is the world’s leading producer of gallium and germanium, which play a role in producing a number of types of compound semiconductors. Compound semiconductors combine multiple elements to improve transmission speed and efficiency.

I have never heard of compound semiconductors before. This page [1] seems to have a decent summary:

> Compound semiconductors are semiconductors that are made from two or more elements... Most compound semiconductors are from combinations of elements from GroupIII and GroupV of the Periodic Table of the Elements (GaAs, GaP, InP and others). Other compound semiconductors are made from Groups II and VI (CdTe, ZnSe and others). It is also possible to use different elements from within the same group (IV)... In the past, compound semiconductors were not used in the widespread commercial applications and high production volumes typical for silicon. These crystals are more difficult to grow than silicon. The number of defects in the crystal is higher, and the cost of making the crystal is higher. Compound semiconductors also tend to be more fragile... In recent years, however, the cost of manufacturing compound semiconductors has come down. It is still much higher than silicon, but at the same time, the special properties of these crystals have become more important for certain applications. Because of their fundamental material properties, compound semiconductors can do things that simply aren't possible with silicon.

Exactly what kinds of applications can compound semis do that silicon semis cannot?

[1] https://global-sei.com/sc/com_semi_e/