presentation on semiconductor fundamental submitted by : md. jubayer ahmed md. mehedi hasan tanvir...
TRANSCRIPT
Presentation on Semiconductor Fundamental
Submitted by :MD. Jubayer AhmedMD. Mehedi HasanTanvir AnjumA.S. Shakur
Submitted to:Mohiuddin MunnaLectureDept. of EEESUST, Sylhet.
Shahjalal University of Science & Technology, Sylhet.Dept. of Electrical & Electronic Engineering.
2010338025201033801920103380072010338013
Structure :The atomic arrangement within a solid can be classified as follows• Amorphous• Polycrystalline• Crystalline
Amorphous:An Amorphous solid is a material in which there is no recognizable long-range order in positioning of atoms within the material.
Crystalline:A crystalline solid is a solid material whose constituent atoms, molecules, or ions are arranged in an ordered pattern extending in all three spatial dimensions.
Polycrystalline:Polycrystalline materials are solids that are composed of many crystallites of varying size and orientation.
Unit cell Unit cell:
The unit cell is a small box containing one or more atoms arranged in 3-dimensions
The unit cell is represented in terms of its lattice parameters.
On the cubic category there are three types of unit cells• Simple cubic • Body-centered cubic• Face-centered cubic
Silicon LatticesIn Si (and Ge) the lattice structure is diamond lattice.
Diamond Lattice:1. Similar to F.C.C but have four additional
atoms.2. Most of the iii-v semiconductors are
diamond lattice.3. Diamond lattice similar to zincblende
structure.
Fig: silicon lattice
Fig: Diamond Lattice Fig: Zincblende Structure
MILLER INDICES The position of the planes or the direction of a vector in the
lattice are usually described by three integers.
HOW TO FIND MILLER INDICES.
Determine the intercepts of the plane intersecting the xyz coordinate.a1 – x direction, a2 – y direction, and a3 – z direction.
Take the reciprocals of the intercepts. h = 1/a1, l = 1/a2, and m = 1/a3.
Reduce the result to the smallest integer.
( hkl) – for single plane and {hkl} for a group of planes.
Negative Miller values are denoted by a bar on top. Example - (ħkl).
Planes without an intersecting intercept are taken as infinite planes (∞).
Obtaining Ultrapure Si:In nature Si is found in a various forms of silicon dioxide or silicates.silicon the second most abundant element in the Earth's crust (about 28% by mass) after oxygen.
Czochralski process.
Thank You