Which semiconductor device has characteristics most similar to a triode vacuum tube?

The Field-Effect Transistor (FET) operates most similarly to a triode vacuum tube because both are voltage-controlled devices. In both components, applying a voltage to a high-impedance control element (the gate in an FET or the grid in a triode) regulates the main current flow without drawing any significant control current itself. In contrast, standard bipolar junction transistors are current-controlled devices, meaning a small base current is required to control a larger collector current. Other distractors like thyristors and triacs are primarily used as electronic switches for power control, not for linear amplification like triodes or FETs.