MOSFET

The MOSFET waited thirty-four years for silicon dioxide to cooperate. Julius Lilienfeld patented the field-effect transistor concept in 1925, but every attempt to build one failed. The problem was surface states—electrons trapped at the semiconductor surface that blocked external electric fields from penetrating into the material. When Shockley, Bardeen, and Brattain encountered this barrier in the 1940s, they invented the bipolar junction transistor instead. The field-effect approach seemed permanently blocked.

The adjacent possible shifted in 1955, when Carl Frosch and Link Derick at Bell Labs accidentally grew a layer of silicon dioxide on silicon wafers. They noticed it protected the surface and prevented dopants from diffusing where they shouldn't. By the late 1950s, Mohamed Atalla realized that thermally grown silicon dioxide could neutralize the surface states that had plagued every earlier attempt. The key was careful cleaning and very pure oxide growth—creating an atomically clean interface between silicon and its oxide.

In November 1959, Atalla and Dawon Kahng built the first working MOSFET at Bell Labs. The device was simple in principle: a silicon channel between two terminals (source and drain), with a thin oxide layer topped by a metal gate. Applying voltage to the gate created an electric field that attracted or repelled carriers in the channel, switching current on or off. No current flowed through the gate itself—the oxide insulated it completely.

The commercial world initially yawned. Bipolar transistors dominated through the 1960s. But MOSFETs could be packed more densely, consumed almost no power when idle, and scaled beautifully as fabrication improved. When Frank Wanlass demonstrated CMOS in 1963—complementary pairs of n-channel and p-channel MOSFETs—standby power dropped by a factor of one million compared to bipolar circuits.

The cascade built slowly, then overwhelmed everything. Intel's 4004 microprocessor in 1971 contained 2,300 MOSFETs. The Intel 1103 DRAM, priced at one cent per bit, replaced magnetic core memory. By 2018, humanity had manufactured 13 sextillion MOSFETs—more than the stars in the observable universe by many orders of magnitude. Today, 99.9% of all transistors are MOSFETs. Apple's M3 Ultra contains 184 billion of them on two connected dies. Intel projects a trillion transistors per chip by 2030. The thirty-four-year wait for silicon dioxide to cooperate produced the most manufactured device in human history.