FET

field-effect transistor

work on surface states

Another field-effect transistor patented

work on surface states

von Neumann architecture

Formulated the von Neumann architecture upon which most modern computers are based

JFET

junction field-effect transistor

Heinrich Welker first patented JFET

first FET built

unable to build FET

Shockley independently envisioned the FET concept

unable to build working device

surface states and the birth of surface physics

- Bardeen explained Shockley's failure to build a working device in terms of surface states

- Bardeen applied the theory of surface states on semiconductors

- (previous work on surface states was done by Shockley in 1939 and Igor Tamm in 1932)

and realized that the external field was blocked at the surface because of extra electrons which are drawn to the semiconductor surface.

- Electrons become trapped in those localized states forming an inversion layer.

- Bardeen's hypothesis marked the birth of surface physics.

- Bardeen then decided to make use of an inversion layer instead of the very thin layer of semiconductor which Shockley had envisioned in his FET designs.

transistor effect and point contact transistor

switch from silicon to germanium and in the process their oxide got inadvertently washed off

After Bardeen's surface state theory the trio tried to overcome the effect of surface states. In late 1947, Robert Gibney and Brattain suggested the use of electrolyte placed between metal and semiconductor to overcome the effects of surface states. Their FET device worked, but amplification was poor. Bardeen went further and suggested to rather focus on the conductivity of the inversion layer. Further experiments led them to replace electrolyte with a solid oxide layer in the hope of getting better results. Their goal was to penetrate the oxide layer and get to the inversion layer. However, Bardeen suggested they switch from silicon to germanium and in the process their oxide got inadvertently washed off.

BJT

bipolar junction transistor

first working transistor built

IGFET

- IGFET based on his theory from 1946

- Bardeen patented the progenitor of MOSFET

- an insulated-gate FET (IGFET)

with an inversion layer.

- The inversion layer confines the flow of minority carriers,

increasing modulation and conductivity,

although its electron transport depends on

the gate's insulator or quality of oxide if used as an insulator,

deposited above the inversion layer.

- Bardeen's patent as well as the concept of an inversion layer forms

the basis of CMOS technology today.

SIT

static induction transistor

invented

a type of JFET

with a short channel

theoretical treatment on the JFET

working practical JFET built

IGFET

The insulated-gate field-effect transistor (IGFET) was theorized as a potential alternative to junction transistors, but researchers were unable to build working IGFETs, largely due to the troublesome surface state barrier that prevented the external electric field from penetrating into the material.

Fast and slow surface states

By the end of the first half of the 1950s, following theoretical and experimental work of Bardeen, Brattain, Kingston, Morrison and others, it became more clear that there were two types of surface states. Fast surface states were found to be associated with the bulk and a semiconductor/oxide interface. Slow surface states were found to be associated with the oxide layer because of adsorption of atoms, molecules and ions by the oxide from the ambient.

atomically clean semiconductor surfaces

At the time Philo Farnsworth and others came up with various methods of producing atomically clean semiconductor surfaces.

focus BJT leave FET

By the mid-1950s, researchers had largely given up on the FET concept, and instead focused on bipolar junction transistor (BJT) technology.

foundations of MOSFET technology

The foundations of MOSFET technology were laid down by the work of William Shockley, John Bardeen and Walter Brattain.

covered the surface of silicon wafer with a layer of silicon dioxide

In 1955, Carl Frosch and Lincoln Derrick accidentally covered the surface of silicon wafer with a layer of silicon dioxide.

FeFET or MFSFET

In 1955, Ian Munro Ross filed a patent for a FeFET or MFSFET. Its structure was like that of a modern inversion channel MOSFET, but ferroelectric material was used as a dielectric/insulator instead of oxide. He envisioned it as a form of memory, years before the floating gate MOSFET.

At Shockley Semiconductor, Shockley had circulated the preprint of their article in December 1956 to all his senior staff

Results of their work circulated around Bell Labs in the form of BTL memos before being published in 1957.

germanium monoxide gate dielectric

In February 1957, John Wallmark filed a patent for FET in which germanium monoxide was used as a gate dielectric, but he didn't pursue the idea. In his other patent filed the same year he described a double gate FET.

device similar to the later proposed MOSFET, didn't explicitly use silicon dioxide insulator

In March 1957, in his laboratory notebook, Ernesto Labate, a research scientist at Bell Labs, conceived of a device similar to the later proposed MOSFET, although Labate's device didn't explicitly use silicon dioxide as an insulator.

neutralization surface states, surface passivation

A breakthrough in FET research came with the work of Egyptian engineer Mohamed Atalla in the late 1950s. In 1958 he presented experimental work which showed that growing thin silicon oxide on clean silicon surface leads to neutralization of surface states. This is known as surface passivation, a method that became critical to the semiconductor industry as it made mass-production of silicon integrated circuits possible.