Gallium is a metal, not a semiconductor. You cannot build a transistor or even a diode with a piece of metal, forget an IC chip containing several transistors.

To create a gallium based semiconductor, it must be ALLOYED with one or more of the following elements: nitrogen, phosphorus, arsenic, or antimony. The simplest semiconductor alloys are: gallium nitride, gallium phosphide, gallium arsenide, and gallium antimonide. Examples of other semiconductor alloys are: gallium nitride phosphide, gallium phosphide arsenide, etc. (these are used in some types of LEDs).

The most common gallium alloy semiconductor for making transistors and IC chips is gallium arsenide. Compared to both silicon and germanium, transistors made of gallium arsenide are significantly faster, and additional speed can be obtained by using nonsaturating logic circuits like ECL.