What are the applications of n - type and p - type semiconductors?
P-Type (and N-Type) Semiconductors (in conjunction) find a wide variety of applications in industries and research areas, and this includes but is not limited to
- LASER(s): -
LASER is an ancronym which stands for Light Amplification by Stimulated Emission of Radiation, and its structural composition consists of both P and N type semiconductors (Extrinsic, means they are either doped with pentavalent or trivalent inpurity), based on this, a LASER can be categorised as either Homojunction LASER or Heterojunction LASER:
- Homojunction LASER: -
In simple terms it's composed of a PN junction with one of the region doped with trivalent and other with pentavalent impurity (now you will appreciate why we have a P-Type water with N-Type one), in this LASER, we basically show band bending diagrams with Quasi Fermi levels EfnEfnand EfpEfp (when PN junction is Forward biased) shifted by the amount equal to the potential applied across the PN juction (just convert it into eV), here basically each wafer provides charge flow (Diffusion-->(due to concentration gradient) plus Drift--> (due to applied electric field)
Note: - Here current density is very high ~ 10^9 A/m^2.
2. Heterojunction LASER: -
In this type of laser basically we deploy a low band gap material (for example GaAs either Nor P-Type) between two high band gap material (AlGaAs--> p+ and AlGaAs-- n-, where p+ and n- are highly doped P-Type and N-Type concentration.) So you would ask what is the use of this LASER?
The ans lies in the fact that this laser has comparitively lower current density (~1mA/m^2) as opposed to homojuntion LASER, and this is because of high potential energy of those 2 wafers (N and P-Type tri-compunds).
3. Solar cell's: -
Same PN junction sandwiched layer concept and unserstood by same device physics.
4. MOSFET's and BJT's: -
MOSFET stands for Metal Oxide Field Effect Transistor and Transistor is in itself combined from two words i.e. Transfer (movement of charge carriers in either direction) + Resistance (Resistance encountered due to material properties and doping concentration), similarly BJT stands for Bipolar junction transistor and here bipolar stands for both charge carriers (holes from P-Type and electrons from N-Type wafer), I'm not going into the device physics of the above mentioned devices into how they work, just wanted to give you an idea that how both P-Type and N-Type contribute for the output you wish to desire either as an amplifier or as a switch.
5. LED's: -
Like LASER ( there is a difference b/w the two which I will cover shortly), LED stands for Light Emitting Diode, and it is also of two types, Heterojunction and Homojunction LED(s), and the principle that differs LED from LASER is the mechanism of radiation, what I mean to say is as stated previously, LASER uses Stimulated Emission for high intense coherent (crest to crest and trough to trough of incident and radiated photon due to de-excitation from the meta-stable state) monochromatic (single wavelength and single frequency (vice-versa).
But in case of LED spontaneous emission takes place and thus light beam is not that coherent.
And much more…
So the infrence from the above device picture leads to he straight fact that P-Type provides charge carriers (holes) N-Type provides electrons and thus sometimes they both are used in conjunction with each other (like in BJT) or either one of them is used for doping purpose (like Mosfets, where only one type of charge carriers flows because of 3 stage process (Accumulation, Depletion and Inversion) to form an inversion layer which is just like a trapezoid highway for electrons if it is N-Mosfet or holes for P-Mosfet, Single Electron transistor (Concept of Quantum dots, where QD can be used as a control gate to pass electrons, similar approach can be used for holes also (since they are also charge carrier--> positive)
P-Type (and N-Type) Semiconductors (in conjunction) find a wide variety of applications in industries and research areas, and this includes but is not limited to
- LASER(s): -
LASER is an ancronym which stands for Light Amplification by Stimulated Emission of Radiation, and its structural composition consists of both P and N type semiconductors (Extrinsic, means they are either doped with pentavalent or trivalent inpurity), based on this, a LASER can be categorised as either Homojunction LASER or Heterojunction LASER:
- Homojunction LASER: -
In simple terms it's composed of a PN junction with one of the region doped with trivalent and other with pentavalent impurity (now you will appreciate why we have a P-Type water with N-Type one), in this LASER, we basically show band bending diagrams with Quasi Fermi levels EfnEfnand EfpEfp (when PN junction is Forward biased) shifted by the amount equal to the potential applied across the PN juction (just convert it into eV), here basically each wafer provides charge flow (Diffusion-->(due to concentration gradient) plus Drift--> (due to applied electric field)
Note: - Here current density is very high ~ 10^9 A/m^2.
2. Heterojunction LASER: -
In this type of laser basically we deploy a low band gap material (for example GaAs either Nor P-Type) between two high band gap material (AlGaAs--> p+ and AlGaAs-- n-, where p+ and n- are highly doped P-Type and N-Type concentration.) So you would ask what is the use of this LASER?
The ans lies in the fact that this laser has comparitively lower current density (~1mA/m^2) as opposed to homojuntion LASER, and this is because of high potential energy of those 2 wafers (N and P-Type tri-compunds).
3. Solar cell's: -
Same PN junction sandwiched layer concept and unserstood by same device physics.
4. MOSFET's and BJT's: -
MOSFET stands for Metal Oxide Field Effect Transistor and Transistor is in itself combined from two words i.e. Transfer (movement of charge carriers in either direction) + Resistance (Resistance encountered due to material properties and doping concentration), similarly BJT stands for Bipolar junction transistor and here bipolar stands for both charge carriers (holes from P-Type and electrons from N-Type wafer), I'm not going into the device physics of the above mentioned devices into how they work, just wanted to give you an idea that how both P-Type and N-Type contribute for the output you wish to desire either as an amplifier or as a switch.
5. LED's: -
Like LASER ( there is a difference b/w the two which I will cover shortly), LED stands for Light Emitting Diode, and it is also of two types, Heterojunction and Homojunction LED(s), and the principle that differs LED from LASER is the mechanism of radiation, what I mean to say is as stated previously, LASER uses Stimulated Emission for high intense coherent (crest to crest and trough to trough of incident and radiated photon due to de-excitation from the meta-stable state) monochromatic (single wavelength and single frequency (vice-versa).
But in case of LED spontaneous emission takes place and thus light beam is not that coherent.
And much more…
So the infrence from the above device picture leads to he straight fact that P-Type provides charge carriers (holes) N-Type provides electrons and thus sometimes they both are used in conjunction with each other (like in BJT) or either one of them is used for doping purpose (like Mosfets, where only one type of charge carriers flows because of 3 stage process (Accumulation, Depletion and Inversion) to form an inversion layer which is just like a trapezoid highway for electrons if it is N-Mosfet or holes for P-Mosfet, Single Electron transistor (Concept of Quantum dots, where QD can be used as a control gate to pass electrons, similar approach can be used for holes also (since they are also charge carrier--> positive)
