Why Iron Or Zinc Can Not Be Dopant Elements Of Silicon

Why does not semiconductor dop with VIA group elements?

Any impurity (donor or acceptor) in silicon has ionization energy Ei, which represents amount of energy needed for jump to conduction or valence  zone. For general impurities (P, B,Sb, As) in silicon Ei~35-45 meV. For other elements Ei is much higher, and close to mid-gap. Because such elements  (platinum Pt,gold Au) helps free carriers to recombine they are called carrier lifetime killers. Other mid-gap impurities,Ni for example, has high diffusion coefficient  and has no practical application  because it is hard to localize them.The rest elements, which ionization energies Ei are in between 60 meV and mid-gap not used because of incomplete ionization.

Why are only Group III & V elements used for doping?

The other answerer has a very complete and correct answer. I do want to add to the answer though. As he said, which dopants to use in each semiconductor is well established. There is a reason why we use Phosphorus and Arsenic to create n-type silicon and Boron to create p-type silicon.The fundamental reason besides the fact they donate or steal and electron is their dopant energy level within the bandgap. For the particular temperature, those dopant must be activated at nearly 100%. For this to occur, a donor site must be as near to the conduction band as possible. Otherwise, it would take a significant amount of energy to ensure a high percentage were activated. Likewise, an acceptor site must be as near in energy as possible to the valence band.Look at the chart below. The best acceptors happen to be group III (boron, aluminum, gallium, indium and thallium in that order). The best donors happen to be group V (antimony, phosphorus, arsenic, bismuth in that order). Lithium is an interesting difference. By giving 1 electron away, it becomes like Helium. So in that sense it does act as a donor.

Why must humans have elements in their bodies? (Iron, magnesium, potassium etc.)?

The kind of smart ass answer is that we have elements in our body because everything is made from elements. So, since everything is made from elements you can’t have a body without elements!Different elements in the body do different things. For example, potassium plays a role in many different ways such resting cellular-membrane potential and hormone secretion and action. PotassiumIron and Magnesium also play very important and specific roles in the body.The fact that these metals play an important role in your body is why people are need to be careful they get enough minerals and vitamins!

Can semiconductors be made of elements other than the ones in group 14?

Yes, we have many semiconductors that are not made of group 14 elements. List of semiconductor materials They include all the III-V  and II-VI semiconductors. III-V semiconductors include Gallium Arsenide - found in most lasers, Gallium Nitride - Used in blue LEDs and High frequency electronic components, Indium Phosphide - Used in High frequency electronic components and optoelectronic devices.II-VI semiconductors include  Zinc oxide can be used in solar cells, LEDs(mostly experimental) [My current work is on Zinc Oxide BTW]P.S. - There are many more types of semiconductors as well, some like Molybdenum Sulphide which one might never expect to even be a semiconductor

Why doping is required in semiconductor?

Semi conductors are devices that have both the properties of conductors and insulators. In the pure form they are called intrinsic semiconductor and when they are not in their pure form pr doped form they are called extrinsic semiconductors. In the purest form the act as an insulator(ideal case). As semiconductors are used for making electronic components, obviously they need to be conducting.Semiconductors are carbon family elements (group 14 in periodic table), the valency of these elements are 4 and they doesn't have any free electrons in the outer most shell. For making the semiconductors conduct there must be some vacant electrons. Doping is the process of adding impurities to the pure form of semiconductor. While adding the impurities there will be occurrence of a holes(a vacancy of electron) or free electrons. The free electron or the holes are responsible for conduction.For making the semiconductor conducting doping is necessary.

Why is carbon not a semiconductor although it is in the same group as silicon and germanium?

Diamond is a semiconductor, with a very large band gap (indirect bandgap).Band structure and carrier concentrationClassification as a semiconductor is mostly a matter of how well you can dope it -- that is, add an impurity at a low concentration to directly and reliably affect its conductivity and band to Fermi level distances.Interestingly enough, diamond (3-d crystalline carbon) can be doped, but not as effectively as in other semiconductors.  Doping of diamondDiamond is a wide-bandgap semiconductor with unsurpassed physical and chemical properties. When doped, semiconducting diamond can lead to the realization of electronic and optoelectronic devices with exceptional properties. Diamond can now be doped p-type, with boron, both during CVD diamond film growth and by ion-implantation, and n-type with phosphorus during CVD growth. This paper reviews the current status of diamond doping and describes the electronic properties of the doped layers. Some potential applications of doped semiconducting diamond are described.The issue is that doping requires the donor level to be very near the band edge energy, but doping both P and N doping in diamond are a fair amount further from the band edge than the donor levels in other semiconductors.n-type doping of diamondHowever, phosphorus has been used successfully to produce n-type diamond, in the sense that the donor level (E in Figure 2) is much shallower than any other donor which can be reproducibly included in diamond. This qualification of the term success is very important: the donor level of P is relatively deep, at 0.6 eV below the conduction band. Therefore at room temperature the number of conduction electrons will be small as the fraction of donors that will be ionized depends on the exponential of the ratio E/kBT.Band structure and carrier concentrationBoron is a deep acceptor level with activation energy of 0.37 eV. So far semiconductor applications of diamond have been based almost exclusively on boron-doped p-type samples (Gildenblat et al. [1991]).