Physics of Semiconductor Engineering Physics I Semester Department

Physics of Semiconductor Engineering Physics I – Semester Department of Applied Sciences PRESENTED BY Vijay Baviskar Assistant Professor R. C. Patel Institute of Technology, Shirpur vijbaviskar. wordpress. com

COURSE OBJECTIVE Students will be able to classify material on basis of band gap Students will be able to define types of Semiconductor. Students will be able to explain conduction in intrinsic semiconductor.

COURSE OUTLINE Classification of Material on Band gap. Intrinsic Semiconductor. Extrinsic Semiconductor. Electrical conductivity in Semiconductor.

UNIT-IV PHYSICS of SEMICONDUCTOR MARKS-16 • Introduction – 1) 2) 3) 4) 5) 6) 7) Band theory of solids Classification of semiconductor Intrinsic & Extrinsic semiconductor Fermi level Conductivity equation for semiconductor pn-junction diode Hall effect

Band theory of solids • According to theory of ‘Hydrogen’ atom. • Isolated single atom has single energy level.

Band theory of solids • Electrons in outermost orbit call as valence electrons, these are interact with each other. • Valence electrons orbital's combine to form molecular orbital's. • Energy diff. become smaller & smaller as number atoms are increased.

Energy level splitting of two atoms • When two atoms come close, the original level split into two energy levels. • Slimily three atoms come close, the original level split into three energy levels.

Energy levels splitting of solids • When ‘N’ atoms interact to each other an energy level to spilt up into ‘N’ levels. • Energy levels splitting The transformation of single energy level into two or more separate energy levels • Splitting of single energy level into band is responsible for Electrical, Magnetic , optical properties of solids.

Energy levels splitting of solids

Band theory of solids • Energy level splitting is greatest for outermost electrons & least for inner electrons. • Energy level splitting is increase with the decreasing the atomic spacing. • Energy band – the manifold levels resulting from splitting are so closely spaced that they form a virtual continuum.

Electron Distribution

Energy band structure of Lithium (3) -

Energy band structure of Beryllium (4) -

Energy band structure of Carbon (6) -

Energy band structure of Silicon (14) -

Definitions • Valence Band (V. B. ) - • Conduction Band (C. B. ) - • Forbidden Band (E. g. ) -

Classification of solids on Band theory • Insulator • Conductor • Semiconductor -

INSULATOR

CONDUCTOR

SEMICONDUCTOR

Concept of Hole

Type of semiconductor • Intrinsic (pure) Semiconductor • Extrinsic (impure) Semiconductor

Intrinsic semiconductor

Intrinsic semiconductor

Extrinsic (impure) Semiconductor • Depending upon which type of impurity is added to pure semiconductor they are classify into two type • P-type semiconductor • N-type semiconductor

P-type semiconductor

N-type semiconductor

Intrinsic semiconductor

P-type semiconductor

N-type semiconductor

Variation of resistivity in case metal & semiconductor due to external physical parameter

Impurity concentration Metal Semiconductor

Temperature Metal Semiconductor

Light Metal Semiconductor