Solid-state electronic components, devices, and systems are based entirely on the semiconductor, such as transistors, microprocessor chips, and the bubble memory. In solid-state components, there is no use of the electrical properties of a vacuum and no mechanical action, no moving parts, although a considerable amount of electromagnetic and quantum-mechanical action takes place within. The expression became prevalent in the 1950s and the 1960s, during the transition from vacuum tube technology to semiconductor diodes and transistors. More recently, the integrated circuit (IC), the light-emitting diode (LED), and the liquid-crystal display (LCD) have evolved as further examples of solid-state devices.

In a solid-state component, the current is confined to solid elements and compounds engineered specifically to switch and amplify it. Current flows in two forms: as negatively-charged electrons, and as positively-charged electron deficiencies called electron holes or just "holes". In some semiconductors, the current consists mostly of electrons; in other semiconductors, it consists mostly of "holes". Both the electron and the hole are called charge carriers. Examples of a non-solid-state electronic components are vacuum tubes and cathode-ray tubes (CRTs). In this device, electrons flow freely through a vacuum from an electron gun, through deflecting and focusing fields, and finally to a phosphorescent screen. For data storage, solid-state devices are much faster and more reliable than mechanical disks and tapes, but are usually more expensive. Although solid-state costs continually drop, disks, tapes, and optical disks also continue to improve their cost/performance ratio.

The first solid-state device was the "cat's whisker" detector, first used in 1930s radio receivers. A whisker-like wire was moved around on a solid crystal (such as a germanium crystal) in order to detect a radio signal.¹

See also

• Semiconductor device
• Solar cell

References