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Why do transistors generate less heat than vacuum tubes?

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NMOS transistorNegative-channel metal-oxide semiconductors (NMOS) employ a positive secondary voltage to switch a shallow layer of p-type semiconductor material below the gate into n-type. For positive-channel metal-oxide semiconductors (PMOS), all these polarities are reversed. NMOS transistors are more expensive, but faster, than PMOS transistors. — transistor NMOS transistor
Negative-channel metal-oxide semiconductors (NMOS) employ a positive secondary voltage to switch a shallow layer of p-type semiconductor material below the gate into n-type. For positive-channel metal-oxide semiconductors (PMOS), all these polarities are reversed. NMOS transistors are more expensive, but faster, than PMOS transistors.

Transistors generate significantly less heat than vacuum tubes primarily because they do not require a heated cathode to function.1

Vacuum tubes rely on thermionic emission, a process that requires heating an electrode to high temperatures to discharge the electrons necessary for operation. This heating process consumes substantial power and produces considerable waste heat.2341

In contrast, transistors are semiconductor devices that produce an adequate supply of current carriers (electrons and holes) at room temperature. Because they eliminate the need for a power-intensive heating element, transistors require much less power from the supply, resulting in significantly lower heat production. This efficiency allows transistors to be packed into much smaller spaces, such as in modern microchips, where minimizing waste heat is essential to prevent the components from melting.15