That's the device we call an FET today. Lilienfeld didn't invent the semiconductor device, that honor is usually given to Karl Ferdinand Braun, who invented a device we know today as the crystal rectifier, or semiconductor diode (clarify: galena or pyrite point-contact diode aka cat's whisker.) Semiconductor effects were first observed by Thomas Johann Seebeck, whose namesake is given to the phenomenon that makes thermocouples possible. But yes, semiconductors were "invented" or noticed, in this case, by pure European White Men. This isn't to discount Lilienfeld's work in any way, modern electronics would be impossible without his electrolytic capacitor. The man's work is so underappreciated it hurts.