September 2016 - Benefits of using a Silicon Diode
Published on: 13/09/2016
Benefits of using a Silicon Diode
Good Insulator - silicon forms on a thin layer of SiO2 which is a very good insulator and can be easily processed. The oxide layer is very useful to form the gates of MOSFET transistors. This layer is also very useful when forming the junctions in a transistor because it acts as a masking layer that prevents the diffusion of the dopants in the regions it protects.
Less Noise - silicon has a larger band-gap (0.7 eV) than germanium (0.2 eV) which means that at the same temperature the noise of the silicon devices is far smaller than the noise of germanium devices, the reverse current of a p-n junction is also smaller for silicon than for germanium.
Found in Nature - silicon is widely found in nature in the form of sand, it is extracted by reduction with carbon. In contrast germanium is not so easily found in nature, and when found is encountered only in chemical compounds that it forms because of its high reactivity.
Collector Cut Off Current - At room temperature, silicon crystal has fewer free electrons than germanium crystal. This implies that silicon will have much smaller collector cut off current than germanium.
Not Easily Damaged - the structure of germanium crystals will be destroyed at a higher temperature. Whereas silicon crystals are not easily damaged by excess heat.
Peak Inverse Voltage Ratings – silicon diodes peak inverse voltage ratings are greater than germanium diodes.
Cost Effective – an important factor about silicon is that it is a cost effective alternative to germanium due to the greater abundance of element. The major raw material for silicon wafer fabrication is sand, which makes it readily available because there is lots of sand available in nature. Silicon is relatively easy and inexpensive to obtain and process. Germanium is a relatively rare material which makes it more expensive and hard to find.
Reverse Current - in a silicon diode is in the range of nano-amperes. The same reverse current is in micro-ampere range for a germanium based diode.
Higher Forward Voltage Potential – a silicon diode has higher forward voltage potential (0.7V) than germanium (0.3V).
Low Reverse Leakage Current –The reverse current in silicon diodes flows in order of micro-Amperes. The germanium diode in reverse falls down because of the accuracy of the non-conduction of the diode. The silicon diode retains its property to a greater extent
Good Temperature Stability – Silicon’s temperature stability is good; it can withstand a temperature range from 140C – 180C whereas germanium can only hold up to 70C.
High Reverse Break Down Voltage - the silicone diode has large reverse breakdown voltage about 70-100V compared to germanium which has the reverse breakdown voltage around 50V.
Large Forward Current - silicon is much better for high current applications as it has very high forward current in a range of tens of amperes, whereas germanium diodes have very small forward current in a range of micro-amperes.
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