Greenleaf Whittier Pickard
Greenleaf Whittier Pickard (February 14, 1877 – January 8, 1956) was an American electrical engineer and inventor. He was largely responsible and most famous for the development of the crystal detector, the earliest type of diode detector, although he was not the earliest discoverer of the rectifying properties of contact between certain solid materials.
Source: Wikipedia — Greenleaf Whittier Pickard (CC BY-SA 4.0)