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