Silicon

Silicon

Occurs as silica (SiO2) & other silicates.Hard & Brittle.

Forms Of Silica

Agate Opal

Pure Silicon

Pure Silicon

Intrinsic Silicon.Covalent Bond.Insulator.Resistivity 2.5 x 105 ohms-cm

Pure Silicon

Pure Silicon Bonding

Why Silicon

Why Silicon

Abundance of SiliconHigher Melting Temperature for Wider

Processing Range.Wider Temperature range of operationNatural growth of SiO2

Why Silicon

• SiO2 growth is needed for high performance MOS.

Doped Silicon

Doping

Adding Certain Elements to Enhance the Conductivity of Semiconductor.

Becomes Extrinsic.Resistivity drops to 0.2 ohms-cm.

Doping of Silicon

Dopant Material

Dopant Material

n-Type Silicon

n-Type Silicon

Pentavalent Dopant Used.More Electrons than Valance Band Holes.Need Little Energy for Excess Electron to Go to

Conduction Band.Majority Carrier Electron & Minority Carrier

Hole.

n-Type Silicon

p-Type Silicon

p-Type Silicon

Trivalent Dopant usedMore Valance Band Holes than Conduction

Band Electrons.Majority Carrier Hole & Minority Carrier

Electron.

p-Type Silicon

p & n Type Silicon