Hello aspirant,

The following is the syllabus in ELECTRONIC DEVICES-

• Energy bands in solids (qualitative ideas only), conductors, insulators and semiconductors, semiconductor diode - I-V characteristics in forward and reverse bias, diode as a rectifier, I-V characteristics of LED, photodiode, solar cell, and Zener diode. Zener diode as a voltage regulator.
• Junction transistor, transistor action, characteristics of a transistor, transistor as an amplifier (common emitter configuration), and oscillator.
• Logic gates (OR, AND, NOT, NAND and NOR). Transistor as a switch.

Hence, valve electronics is not in the NEET syllabus.

Hope it helps!