In modelling the transport properties of semiconductor, is it mandatory to consider the background doping of semiconductor
Any impurities will act as scattering centres and if in high enough concentration, will therefore influence carrier mobility.
As the colleagues pointed out the back ground doping may influence the transport parameters appreciably. Do you mean by background doping that the residual doping formed unintentional during the processing of the material? Any how, to start with any material you have to fully characterize this material since its staring properties may affect much the produced device performance. So, from the basic and systematic point of view it is mandatory since from the principle point of view any doping may affect;
The carrier concentration density and type
The mobility of the charge carriers
The minority carrier lifetime
especially the minority carrier lifetime is very sensitive to .deep lying impurities.Very light doping can kill the lifetime. However minority carrier lifetime is more important for bipolar devices.
wish you success
Doping will affect carrier concentration and electric field. So, carrier mobility will be affected and hence transport properties.
Yes...It is mandatory :)
====================== You wanna know why?===========
1- The background doping (DOP=Nd-Na) is explicitly needed in the Poisson Equation. Therefore the simulator can't calculate the electric field and potential distribution without knowing it.
2- Almost all physical parameters (drift mobility, lifetime, impact ionization, thermal conductivity,...etc.) depend implicitly on the doping concentration. Inside the simulator, all physical parameters are actually expressed as functions of DOP, through well-known modes.
==================What to do if you don't know DOP?===================-=
My dear, I know you wanna simulate the electrical characteristics of a semiconductor device and you don't know the doping profile, which is needed as input in your simulator
So, what to do?
1- If you don't have a specific problem for a specific device, try a simple doping distribution (constant in each region of the device (e.g., for a BJT, try NE=10E19m NB=10E16, NC1=10E14, NC2=10E18). You can also assume ERFC or Gaussian distributions in the Emitter and Base regions, with the above maximum doping.
2-If you wanna simulate a specific device, search for its datasheet
2- If you don't find it explicitly, you can predict it from the published parameters (such as life time or drift mobility) through the well know physical models of these parameters.
3- You can extract the doping profile experimentally, through the well known Semiconductor measurement Methods. Download my Book Chapter (here in ResearchGate) to know how:
https://www.researchgate.net/publication/287866127_Measurement_of_the_Semiconductor_Parameters
Thank you for asking :)
Chapter Measurement of the Semiconductor Parameters
Doping affects transport both via electrostatics and by introducing a source of carrier scattering. The former will affect the number of available carriers, while the latter will reduce their mobility.
If you are interested in transport in a semiconductor device such as a MOSFET, you need to consider the effect of screening. in a bulk semiconductor charge neutrality dictates that the number of carriers and dopants must be roughly equal for their charges to cancel out. In a device, however, carrier density is controlled electrostatically (e.g. by a gate) and thus decoupled from doping density.
Screening reduces the effect of impurity scattering. This means that if you carrier number is low the carriers are exposed to the bare impurities, whereas if you have many carriers they will screen the impurities, making impurity scattering less effective.
In the context of a MOSFET, background doping will especially affect the off-current because in the off-state there are no carriers in the channel to screen the impurities, making them very effective scatterers.
Background doping is related to defect issue that can suppress the carrier transport properties . To avoid this impact on overgrowth devices performance background doping is is factor.
For a nominally undoped semiconductor, impurities, self-doping effects during growth and other unintentional dopants will influence the conductivity significantly. For a heavily doped semiconductor it is not so relevant. Most simulations are meaningless for experiments if the doping level is not known at all.
- Badges
- Science topic
- Similar topics
- Physical Sciences
- Materials Science
- Materials
- Semiconductor