n-type silicon

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n-type silicon

The use of n-type and p-type silicon is a foundation concept in the design of transistors. Pure silicon is not conductive. However, it can be made conductive by adding other elements to its crystalline structure, which then become known as "n-type" or "p-type" silicon.

The interaction of n-type and p-type silicon to electric fields and to each other is used to make areas in a transistor change from conductive to non-conductive and vice versa (see crystalline semiconductor). See FET, MOSFET, bipolar transistor and doping.

N-Type (Negative)
N-type silicon is silicon that has been chemically combined (doped) with phosphorus gas to make it conductive. A silicon atom has four electrons in its outer shell and bonds tightly with four surrounding silicon atoms creating a crystal matrix with eight electrons in the outer shells. However, phosphorus has five electrons, and when combined, the fifth electron becomes a "free" electron that moves easily within the crystal when a voltage is applied. Because the charge carriers are electrons, n-type refers to a negative charge.

P-Type (Positive)
In contrast, p-type silicon is silicon doped with boron gas that turns it into a conductive material that readily accepts electrons when voltage is applied. Boron has only three electrons in its outer shell and can bond with only three of the four surrounding silicon atoms. This leaves one silicon atom with a vacant location in its outer shell, called a "hole," that readily accepts an electron. Because the charge carriers are holes, p-type silicon is said to have a positive charge.


N-Type and P-Type
This is a very conceptual illustration of the atomic structure of n-type and p-type silicon. (Image courtesy of TechBites Interactive, www.techbites.com)
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The derivatives use policy characteristics variables are: 1) NTYPE, which captures comprehensiveness of derivative usage by taking the value of zero if the firm does not use derivatives, the value of one when the firm uses only FX derivatives or only IR derivatives, and the value of two if the firm uses both types of derivatives; 2) NCONTR, which captures sophistication of derivative usage by taking the number of different derivative contracts (ranging from 0 to 6) the firm uses; and 3) AMT, total notional dollar amount of derivatives used.
In Panel B, acquirer firms are classified based on NTYPE.
The USER, NTYPE, and NCONTR variables have significant positive coefficients after controlling for transaction variables and acquirer characteristics.
derivatives use policy characteristics USER, NTYPE, NCONTR, or AMT) that will be used as a key independent variable in the structural equation.
DERIVATIVES is alternatively one of the following: USER is a dummy variable that takes value one if a firm uses any kind of derivatives against foreign exchange risk or interest rate risk, and otherwise zero; NTYPE is the number of types of derivatives used, that is, FX and/or IR, or none and thus takes values from zero to two; NCONTR is the number of different derivative contracts used by the firm and based on Swaps Monitor's database it can take values from zero to seven; and AMT is the total dollar amount of derivatives used.
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T = NTYPE = number of years ill which NTYPE has the value I (so T takes values from 0 to 7)