1 Crytal Properties and Growth of Semiconductors1晶体及生长特性的半导体

1、11. crystal properties and growth of semiconductorsnelectrical behavior of solidsnarrangement of atoms1.1. semiconductor materials electrical conductivity intermediate between metals and insulators2what distinguishes semiconductors? -resistance/resistivity-crystalline structure the resistance of a b

2、ar of material with dimensions l, w, t: resistivity is:metals: 102 -cmsemiconductors: 10-3 -cm 102 -cmrlwtwtl3figure 1: electrical conductivities of some common materials.4*conductivity of semiconductor material can be varied over orders of magnitude by changes in-temperature-optical excitation-impu

3、rity contentperiodic table:column iv si, ge elemental semiconductorsiii-v compound semiconductors example:gaasii-vi compound semiconductors example:cdte5the portion of periodic table where semiconductors occur 6binary compounds: gaas, gap, gan, cdte, inp etc.ternary compounds: algaas, gaasp, hgcdte,

4、 etc.quaternary compounds: ingaasp, algainas,etc.applications:*transistors, integrated circuits (si)*light emitting diodes (leds) (gaas,gan, gap)*lasers (algainas, ingaasp, gaas, algaas)*light detectors(si, ingaasp, cdse, insb, hgcdte)71.2. crystal latticessolids classified according to atomic arran

5、gement:vcrystallinevamorphous vpolycrystalline (a) crystalline(b) amorphous(c) polycrystalline 8the atoms making up the crystal are arranged in a periodic fashion called lattice.unit cell is a representative of the entire lattice and is generally repeated throughout the structure.primitive cell is t

6、he smallest unit cell that can be repeated to form the lattice.crystal lattice determines: density of solid (mechanical property) allowed energy bands of electrons (electrical property).9cubic latticessimple (sc) body-centered (bcc) face-centered (fcc)a lattice constant10diamond lattice diamond latt

7、ice is an fcc plus placing atoms a, a, a (in x, y and z direction) from each atom in the fcc.construction of a diamond lattice from two interpenetrating fcc sublattices.top view 11diamond lattice of si from different angles of view12*diamond (zincblende) lattice - typical of most of the commonly use

8、d semiconductors.*characteristic of si, ge, iii-v compounds.*possible to vary the composition of alloy by choosing the fraction of numbers of the atoms, par example:alxga1-xas (x % of al, (1-x)% of ga)inxga1-xasyp1-y13conclusionnatomic arrangement in certain planes in crystal is important to many of the mechanical, metallurgical, and chemical properties of the material. ncrystals cleaved along certain atomic planes, resul