Carver Mead (CalTech Professor) – Lessons from the Early Days of Semiconductors (Jun 2019)


Chapters

00:00:18 History of Controlled Electrical Current
00:04:08 Early Experiments in Semiconductors and the Hall Effect
00:13:44 Early Applications of Semiconductors
00:17:24 Early Semiconductors and the Discovery of Silicon Detectors
00:24:15 Early Developments in Radio and the Emergence of Crystal Sets
00:28:05 Origins of Mobile Internet Innovation
00:30:20 Birth of the MOSFET: Lilienfeld's Pioneering Work
00:37:07 Quantum Mechanics and the Development of Semiconductors
00:42:15 Development of Silicon Point Contact Detectors for Radar Systems
00:45:10 Birth of the Metal Semiconductor Contact
00:48:51 Birth of the Transistor
00:56:45 Automated Transistor Manufacturing in the 1950s
00:59:17 Genesis of Integrated Circuits
01:10:19 Evolution of Semiconductor Devices and the Emergence of Neural Networks
01:19:41 Evolution of Technology in the Semiconductor Industry
01:23:49 Politics and Technology Development
01:30:33 Challenges of Innovation in a Groupthink Environment

Abstract

“Pioneering the Future: A Journey Through the Evolution of Semiconductor Technology”

This article delves into the transformative journey of semiconductor technology, tracing its origins from the primitive sparks of electricity to the sophisticated electronics that permeate our modern world. Benjamin Franklin’s qualitative contributions to electricity preceded Volta’s invention of the voltaic cell, enabling steady voltage generation and transforming electricity into a controllable force, paving the way for battery development and diverse applications. Faraday’s experiments were pivotal, leading to the discovery of electromagnetic induction and the measurement of resistance in various materials, including silver sulfide, a semiconductor with unique properties. His work with Wheatstone’s null principle allowed for precise measurements of resistance without absolute calibration of the galvanometer. Braun’s investigations into the resistance of various minerals led to the discovery of asymmetric conduction, where current flow was easier in one direction than the other, marking the beginning of solid-state electronic devices. Hall’s exploration of the magnetic field’s influence on current-carrying wires led to the observation of the Hall effect, revealing the sideways movement of charge carriers and providing evidence for the existence of mobile charges within conductors.

Volta’s Invention and Early Electricity

The transformation of electricity from sporadic sparks to a steady, controllable force was revolutionized by Alessandro Volta’s voltaic cell. This early battery, consisting of a stack of alternating copper and zinc discs separated by brine-soaked cloth, marked the first consistent source of electric current. Volta’s work was partly inspired by Luigi Galvani’s experiment with a frog’s leg and two different metals, which led to the concept of “animal electricity.” Volta’s voltaic pile demonstrated a continuous electric current, underpinning the development of batteries and their wide-ranging applications.

Faraday’s Contributions

Michael Faraday’s experiments led to seminal discoveries such as electromagnetic induction and the understanding of resistance in materials like silver sulfide, a notable semiconductor. Faraday’s methodical approach, including his collaboration with Wheatstone using the null principle, enabled precise resistance measurements without needing to calibrate the galvanometer. His observations on heating silver sulfide, which showed a decrease in resistance contrary to the behavior of metals, were crucial in identifying it as a semiconductor, thereby introducing a new class of materials with fascinating properties.

Braun’s Experiments and the Birth of Solid-State Devices

Ferdinand Braun’s research into the electrical resistance of minerals uncovered the phenomenon of asymmetric conduction. This discovery, where current flows more easily in one direction than the other, was a groundbreaking moment, marking the inception of solid-state electronic devices.

Understanding the Hall Effect

Edwin Hall’s study of the effects of a magnetic field on current-carrying wires led to the discovery of the Hall effect. This observation demonstrated the lateral movement of charge carriers within a conductor, providing vital evidence for the existence of mobile charges and advancing our understanding of electrical conduction.

Radio Communication and Semiconductors

The progression of radio communication technology, particularly through the efforts of Heinrich Hertz and Guglielmo Marconi, was significantly boosted by incorporating semiconductors in radio receivers. Hertz’s experiments in transmitting and receiving radio waves over distances laid the groundwork for Marconi’s practical radio communication system, which enabled maritime communication. Early radio receivers, initially crude and requiring substantial radio energy, evolved with the innovation of rectifying signals, transforming radio waves into audible sounds and marking the beginning of semiconductors’ widespread use in electronics.

The Era of Crystal Detectors and Controlled Conductivity

The advent of crystal detectors in early radios, especially with the development of a stable silicon crystal detector by Picard, marked a significant advancement in radio technology. These detectors, utilizing the distinct properties of semiconductors, offered a reliable means for rectifying radio signals. Concurrently, Bittecker’s research into the controlled conductivity in semiconductors laid the foundation for modern electronics. His studies on varying conductivity and the effects of impurities led to the groundbreaking discovery of controlling semiconductor conductivity through chemical treatment, a concept pivotal to today’s semiconductor devices.

The Rise of Vacuum Tube Technology

The 1920s saw a revolution in radio technology with the advent of vacuum tubes, notably through Irving Langmuir’s development of high-power transmitting tubes at General Electric. These tubes, capable of rectifying voltages up to 100,000 volts, made broadcast radio feasible by reaching larger audiences. The initial content offered included news, entertainment, and music. Langmuir’s 1913 invention of a mass-producible vacuum tube significantly improved radio signal amplification, marking a crucial advancement in radio technology.

Lilienfeld’s Vision and Transistor Inventions

Julius Edgar Lilienfeld, inspired by vacuum tube advancements and a member of a research group exploring quantum theory, contributed significantly to the evolution of transistors. His unconventional views on electron behavior and experimental work culminated in the invention of the MESFET and MOSFET, fundamental to modern electronics. Lilienfeld’s vision of a semiconductor device for signal amplification led to the MOSFET’s development, a device critical in the miniaturization of electronic components and ubiquitous in today’s digital systems.

The Impact of World War II and the Rad Lab

World War II significantly influenced semiconductor technology, especially with the Rad Lab’s focus on electronics and antenna research. The U.S. Navy’s adoption of semiconductor detectors during the war highlighted their reliability and stability in military applications. The development of small, mass-producible semiconductor detectors using silicon and germanium was a major breakthrough, leading to more compact and reliable radar systems.

Schottky’s Theory and the Birth of the Transistor

Walter Schottky’s 1942 theory on metal-semiconductor contacts provided a crucial understanding of these interfaces, paving the way for research in point contact devices during World War II. Concurrently, at Bell Laboratories, the discovery of the point contact transistor by Bardeen and Brattain, under Shockley’s guidance, marked a turning point in semiconductor device development. The introduction of the junction transistor, a more reliable and controllable structure, was a significant advancement, further propelled by Penkov’s method for creating p-n-p transistor structures and Raytheon’s introduction of the CK722 transistor.

The Advent of Integrated Circuits

The development of integrated circuits, notably through the contributions of Jack Kilby and Bob Noyce, represented a monumental shift in the electronics industry. This advancement was furthered by the planar process and the invention of CMOS logic and dynamic RAM, crucial technologies in the field.

The Future of Computing and Challenges Ahead

The slowing of Moore’s Law and the emergence of new technologies like neural networks indicate a changing landscape in computing. Carver Mead’s insights emphasize the need for continuous innovation and the challenges posed by groupthink in the technological field.

Conclusion

The evolution of semiconductor technology, from its origins to its current state, exemplifies a journey marked by innovation and discovery. As we approach new technological frontiers, the legacy of pioneers such as Volta, Faraday, Braun, and Lilienfeld continues to inspire and guide future engineers and scientists in their quest to expand the boundaries of what is possible.

Additional Information

Origins of Silicon Transistors

Bell Labs researchers developed a method for creating junctions in silicon by diffusing impurities, leading to faster transistors and the ability to fabricate multiple transistors on a single silicon wafer.

Birth of Integrated Circuits

Bill

Shockley’s team at Caltech and Fairchild Semiconductor, co-founded by Gordon Moore, John Herney, and Bob Noyce, made significant strides in developing silicon transistors. Texas Instruments’ introduction of a high-frequency silicon transistor inspired Jack Kilby’s idea of connecting transistors and resistors on a single silicon wafer.

The Herney-Noyce Insight

John Herney’s concept, signed off by Bob Noyce, of connecting any part of a transistor using a wire, was pivotal in developing the modern integrated circuit, a vision shared by Jack Kilby.

Supplement: Carver Mead’s Insights

The Tragedy of Early Transistor Pioneers

Oleg Losev’s failure to see the potential of his work, due to his choice of copper sulfide instead of selenium, underscores the importance of material selection in technological advancements.

Fostering Creativity

Caltech’s culture of exploring unorthodox directions and avoiding groupthink is vital for fostering groundbreaking discoveries. The Bell System’s limitations on commercializing inventions highlight the impact of external factors on technological progress.

Politics and Technology

The increasing political influence on technology underscores the need to consider external factors in technological advancements.


Notes by: MythicNeutron