Gallium nitride (GaN) switch technology has enabled a major advance in the miniaturization of chargers and adapters. GaN transistors switch very efficiently. This allows the development of converters that can either operate at much higher switching frequency than a circuit using equivalent silicon devices, potentially reducing transformer size, or provide solutions that deliver significant system efficiency improvements, reducing or eliminating the need for heat sinks.

Source: GaN Enabling a Revolution in Charger Design | EE Times