Semiconductor Materials- Types & Properties

Material Science

Semiconductor Materials Types

  1. Elemental Semiconductor materials
  2. Compound Semiconductor materials
  3. Amorphous Semiconductor materials

1. Elemental Semiconductor materials

Example: Ge, Si, C, B, Al, Ga, P, As, Sb, Bi, etc.

a). Arsenic (As)

  • It is pentavalent semiconductor material.
  • It is used as donor N-type semiconductor material.
  • When it is alloyed with gallium, then it is used in the fabrication of LED.

b). Selenium (Se)

  • It is used in a photovoltaic cell.

2. Compound Semiconductor materials

As conductivity and band gap are limited for Elemental Semiconductor materials hence their usefulness is limited. So, group III-V, II-VI, IV-IV, IV-VI semiconductors are used to provide better properties.

a). III-V Semiconductor material

  • They provide a wider range of band gap and extended ampere range of a device.
  • The structure is zinc blende and diamond cubic.
  • Example: GaAs, AlP, etc.

GaAs material

  1. large band gap material.
  2. large electron mobility which helps in high-speed switching.
  3. direct band gap material
  4. It is 10 times costlier than Silicon.
  5. It is 2.5 times faster than a silicon based device.
  6. In GaAs crystals, Ga substitute corner and face atoms where as takes place of 4 inside atoms.

Applications

  1. LED
  2. LASER
  3. Satellite amplifier

b). Group II-VI Semiconductor material

  • The band gap is larger than group III-V semiconductor.
  • Examples: CdS, CdSe, CdTe, ZnS, ZnSe, etc.
  • CdS, CdSe, CdTe can be used as photo conductors.

c). Group IV-IV Semiconductor material

  • Example: SiC
  • The band gap of SiC is 3eV.
  • X-SiC can be used for high-temperature devices.
  • One drawback is that it is expensive and not easy to manufacture.

d). Group IV-VI Semiconductor material

  • Examples: PbS, PbSe, PbTe
  • In this semiconductor, excess Pb gives rise to N-type semiconductor and less Pb gives rise to a P-type semiconductor.

3. Amorphous Semiconductor Material

  • The structure is similar to super cooled liquid.
  • Atoms up to first nearest neighbours are arranged periodically but the atoms which are away from the first nearest neighbour are found to be arranged randomly.

There are 3 types of Amorphous Semiconductor Material

a). Elemental Amorphous Semiconductor

Examples: Ge, Si, Se, Te, etc.

b). Covalent Amorphous Semiconductor

Examples: Ge, Te, etc.

c). Ionic Amorphous Semiconductor

Examples: Al2O3, V2O5, etc.

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