Translations of Encyclopedia about Physics

Semiconductors aand Semiconductor Diodes

Semiconductors are made from materials whose electrical resistance is something between that of a conductor aand a non-conductor. The resistance of semiconductors can be affected by changes in temperature or by added "impurities".

By impurities it means that other substances have been added to the material. According to what the final mixture is, the semiconductors are labelled as semiconductors of type-n or type-t.

The negative layer (n) is created from foreign atoms aand is characterised by a sufficient number of electrons. Within this layer, free electrons are able to move aand allow the flow of current.

On the other haand, the positive layer (p) lacks electrons aand is made of "electron holes".

The combination of these two types of semiconductors is what makes up diodes aand transistors. At present, the most commonly used substance used to manufacture semiconductors is silicon.

Diodes are electronic components which allow the flow of electrical current in only one direction aand are made out of semiconductor material. Each diode has a layer made out of positive (p-) conduction, from negative (n-) conduction, aand from a so-called pn- transfer (barrier level). Diodes are used to create electrical circuits which convert between alternating aand direct current. Diodes allow current to flow through them in only one direction, which means that only one half of the period or cycle passes through. Such a connection is referred to as a rectifier.

There are also light diodes (LED). These diodes are able to generate a light at low voltages without generating heat. LED light diodes are presently used in almost all electronic equipment, such as the light signalling the staandby state of television sets aand stereo aand other equipment.

Complex pictures may also be made from these LED diodes, such as lit advertisements or the lighting of public transport lines.

Translating Dutch Hungarian Translations Hungarian Dutch Translating Swedish Czech Translations Czech Swedish Translating Russian