1. Solid State Components The term solidstate refers to the ability to control electron flow in solid substances rather than electromagnetic relay mechanical movements. At the early stages in the development of electricity the opening and closing of switches was done by electromagnets. A relay is a component that allows a current to pass through a coil of wire wrapped around an iron core. This causes the core to become magnetized and pulls the switch closes. The term solidstate refers to the ability to control electron flow in solid substances rather than electromagnetic relay mechanical movements. At the early stages in the development of electricity the opening and closing of switches was done by electromagnets. A relay is a component that allows a current to pass through a coil of wire wrapped around an iron core. This causes the core to become magnetized and pulls the switch closes.

2. When the current is stopped the spring-loaded switch in the relay snaps back to open setting. These relays were used to run computers built as early as the 1920s and large governmental agencies were running these computers to solve mathematical equations and scientific problems (too bulky and expensive for the common person to own). When the current is stopped the spring-loaded switch in the relay snaps back to open setting. These relays were used to run computers built as early as the 1920s and large governmental agencies were running these computers to solve mathematical equations and scientific problems (too bulky and expensive for the common person to own).

3. These computers were so large that they filled rooms the size of your classroom. Each time a “query” was run the computer would make thousands of loud clicking noises due to the electromagnetic relays snapping open and closed. These computers were so large that they filled rooms the size of your classroom. Each time a “query” was run the computer would make thousands of loud clicking noises due to the electromagnetic relays snapping open and closed.

4. In 1883 while Thomas Edison was investigating light bulbs and filaments, he noticed that electrons could be driven off a hot filament of a lamp and collect them on a receiving plate. He called this the “Edison Effect”. In 1904 J.A. Fleming built a circuit (in a vacuum tube) that changed AC to DC (this is known as rectifier). In 1883 while Thomas Edison was investigating light bulbs and filaments, he noticed that electrons could be driven off a hot filament of a lamp and collect them on a receiving plate. He called this the “Edison Effect”. In 1904 J.A. Fleming built a circuit (in a vacuum tube) that changed AC to DC (this is known as rectifier).

5. Dr. Lee Deforest went on to produced a vacuum tube diode, that used concepts developed by Thomas Edison, that allow current to flow in only one direction through a circuit. Dr. Lee Deforest went on to produced a vacuum tube diode, that used concepts developed by Thomas Edison, that allow current to flow in only one direction through a circuit.

6. This was the earliest form of current control that was not done by relays. Soon after Transistors (or triodes) were developed by placing a control grid in the path of the flowing electrons. Now they had a variable way to control current instead of a switch from on to off. This was the earliest form of current control that was not done by relays. Soon after Transistors (or triodes) were developed by placing a control grid in the path of the flowing electrons. Now they had a variable way to control current instead of a switch from on to off.

7. It wasn’t until 1948 at Bell Laboratories where three scientists Shockley, Brattian, and Bardeen came up with a way to build diodes, triodes, and rectifiers without the need for vacuums tubes. These scientists used silicon- based materials to produce components that control electron flow within solid substances A.K.A Solid-State. It wasn’t until 1948 at Bell Laboratories where three scientists Shockley, Brattian, and Bardeen came up with a way to build diodes, triodes, and rectifiers without the need for vacuums tubes. These scientists used silicon- based materials to produce components that control electron flow within solid substances A.K.A Solid-State.

8. Silicon can be modified to act like a conductor or an insulator depending on the application and therefore is referred to as a semiconductor. Silicon can be modified to act like a conductor or an insulator depending on the application and therefore is referred to as a semiconductor.

9. Several materials can be use to produce semiconductors, but silicon, the main ingredient of sand, is the most widely used in solid state circuits. Silicon forms 27.7 % of the earth’s crust so there is an endless resource, and the only other material that is more common is oxygen. Silicon is rarely found in its pure state, but when purified it is dark gray in color. Several materials can be use to produce semiconductors, but silicon, the main ingredient of sand, is the most widely used in solid state circuits. Silicon forms 27.7 % of the earth’s crust so there is an endless resource, and the only other material that is more common is oxygen. Silicon is rarely found in its pure state, but when purified it is dark gray in color.

10. Because of silicon ‘s crystal structure in pure form silicon is a good insulator. Because of silicon ‘s crystal structure in pure form silicon is a good insulator. There are two reasons silicon atoms are so useful as a semiconductive material: There are two reasons silicon atoms are so useful as a semiconductive material:

11. Silicon, like diamonds, form crystal structures that hold a very tight bond that act as a good insulator. A silicon atom has 14 protons and 14 electrons but only 4 electrons are in the valence (outer most) shell. A valence shell can actually hold 8 electrons and so silicon finds other silicon atoms to share electrons in its outer shell. This is know as a covalent bond. Silicon, like diamonds, form crystal structures that hold a very tight bond that act as a good insulator. A silicon atom has 14 protons and 14 electrons but only 4 electrons are in the valence (outer most) shell. A valence shell can actually hold 8 electrons and so silicon finds other silicon atoms to share electrons in its outer shell. This is know as a covalent bond.

12. and in its outer valance shells, as seen in the periodic table box shown below, but it would prefer to have 8 to become Isoelectrically neutral (acting like Argon which is a neutral Ions), see fig 8 - 1a. So naturally each silicon atom easily finds four other atoms to share four other electrons. and in its outer valance shells, as seen in the periodic table box shown below, but it would prefer to have 8 to become Isoelectrically neutral (acting like Argon which is a neutral Ions), see fig 8 - 1a. So naturally each silicon atom easily finds four other atoms to share four other electrons.

13. This creates the very stable bond called a covalent bond that forms a crystal structure. Fig 8 - 1b shows a cluster of silicon atoms sharing valance shell electrons. Notice that each atom has a total of 8 electrons in their valance shell once they have combine with other atoms. This creates the very stable bond called a covalent bond that forms a crystal structure. Fig 8 - 1b shows a cluster of silicon atoms sharing valance shell electrons. Notice that each atom has a total of 8 electrons in their valance shell once they have combine with other atoms. Fig. 8 - 1a Fig. 8 - 1a Fig 8 - 1b Fig 8 - 1b

14. Silicon crystal in pure form is an insulating material unable to allow current to flow because of the tight bond the atoms make with each other. In the Periodic Table, Silicon is shown as Si with an atomic number of 14 and a shell structure of (Ne)3s 2 p 2 (Ne has a structure of 1s 2 2s 2 p 6 ). Silicon crystal in pure form is an insulating material unable to allow current to flow because of the tight bond the atoms make with each other. In the Periodic Table, Silicon is shown as Si with an atomic number of 14 and a shell structure of (Ne)3s 2 p 2 (Ne has a structure of 1s 2 2s 2 p 6 ).

15. When bonded to other silicon atoms it shares another 4 electrons to act Isoelectrically and become neutral. This bond is so tight that it does not allow electrons to travel from one atom to the next. When bonded to other silicon atoms it shares another 4 electrons to act Isoelectrically and become neutral. This bond is so tight that it does not allow electrons to travel from one atom to the next.

16. 2) Scientist found out that certain foreign atoms mixed in with the silicon could produce materials that can become good conductors. These foreign atoms can introduce too many or too few electrons creating an imbalance in the crystalline structure. Fig 8-2 shows how silicon crystals can be grown in the laboratory. 2) Scientist found out that certain foreign atoms mixed in with the silicon could produce materials that can become good conductors. These foreign atoms can introduce too many or too few electrons creating an imbalance in the crystalline structure. Fig 8-2 shows how silicon crystals can be grown in the laboratory.

17. A seed string is inserted into a molten silicon liquid and the atoms begin to attract one another to for a pure silicon mass. If trace amounts of impurities such as Boron or Phosphorous are salted into the molten silicon an insulative material can become a useful ion capable of conducting electronics. A seed string is inserted into a molten silicon liquid and the atoms begin to attract one another to for a pure silicon mass. If trace amounts of impurities such as Boron or Phosphorous are salted into the molten silicon an insulative material can become a useful ion capable of conducting electronics.

18. Boron is very similar to silicon except it only has 3 electrons in its outer shell compared to silicon’s 4 electrons. If a silicon crystal is salted with a few Boron atoms a slight lacking of electrons is produced and provide places that need to be filled by free electrons. Known as P-type materials this mixture allows current to flow by the movement of holes. Boron is very similar to silicon except it only has 3 electrons in its outer shell compared to silicon’s 4 electrons. If a silicon crystal is salted with a few Boron atoms a slight lacking of electrons is produced and provide places that need to be filled by free electrons. Known as P-type materials this mixture allows current to flow by the movement of holes.

19. The picture on the right shows a silicon crystal salted with a few phosphorus atoms. The picture on the right shows a silicon crystal salted with a few phosphorus atoms. Phosphorus is similar to silicon except it has 5 electrons in the valance shell, one more than is needed. This creates a negatively charged crystal that has an surplus of electrons. Known as N-Type materials Crystals salted with Phosphorous allow current to flow by electrons. Phosphorus is similar to silicon except it has 5 electrons in the valance shell, one more than is needed. This creates a negatively charged crystal that has an surplus of electrons. Known as N-Type materials Crystals salted with Phosphorous allow current to flow by electrons.

20. If an N-Type and a P-Type material are joined together a solid-state junction is established and depending on the polarity of the power source allows or stops current. If an N-Type and a P-Type material are joined together a solid-state junction is established and depending on the polarity of the power source allows or stops current.

21. The significance of this ability to create Semiconductors is that these materials can conduct and respond just as the old vacuum tube diodes and transistors or even older relay switches, yet these are cheaper to build, more durable, and much smaller. The rest of this lesson is introducing a few very common solid- state components that will most likely be involved in every circuit you will ever build. The significance of this ability to create Semiconductors is that these materials can conduct and respond just as the old vacuum tube diodes and transistors or even older relay switches, yet these are cheaper to build, more durable, and much smaller. The rest of this lesson is introducing a few very common solid- state components that will most likely be involved in every circuit you will ever build.