The electric conditions of any elements can be depend on its lattice-structure and the electrons shells structure. Here we learn two famous semiconductor Si and Ge which have Diamond lattice-structure. The schematic of the Silicon is shown in Fig.3a.
Si(and Ge) is a tetravalent because silicon's electric structure is 1s2 2s2 2p6 3s2 3p2. If we recall that K and L shells of Si is fully complete because of 1s2 2s2 2p6. Thus the remaining 3s2 3p2 contains valence electrons. Then after two s states and two p states create sp3 shells.
These shells joins with the neighboring shells and create co-valent bond. If say in simple the atom contains four valence electron and it creates four co-valent bond with the four neighbor atoms valence electrons which shows in Fig.3b.
The electrons which in co-valent bond stay static at 0K temperature. Thus reacts as an insulators.
At room temperature, crystal atom contains thermal oscillations. For thus reason some co-valent bond breaks and electron is now a free electron and participating in electric current. Some positive charge create at the place of free electron and it try to catch the other free electron at that place. This empty place is called "Hole".
At these situation we will provide Potential Differene between crystal two ends, the free electrons travels negative side to positive side of battery and produce electric current which shows in Fig.3c.
Fig.3c.
Under effect of the thermal oscillation and external electric field, other free electrons break the co-valent bond and jump in to the hole and creats new holes. For these formation we can say that electrons travels negative sides to positive sides and holes travels positive sides to negative sides.
Thus, Two types of electric current flow in the semiconductor which are as
[1] the motion of free electrons
[2] the motion of free electrons which jumps into the empty holes
Semiconductors have ne and nh which follows free electrons and holes respectively but in intrinsic semiconductor it is equal and it is expressed with ni.
ne=nh=ni
Fig.3a.
Si(and Ge) is a tetravalent because silicon's electric structure is 1s2 2s2 2p6 3s2 3p2. If we recall that K and L shells of Si is fully complete because of 1s2 2s2 2p6. Thus the remaining 3s2 3p2 contains valence electrons. Then after two s states and two p states create sp3 shells.
These shells joins with the neighboring shells and create co-valent bond. If say in simple the atom contains four valence electron and it creates four co-valent bond with the four neighbor atoms valence electrons which shows in Fig.3b.
Fig.3b.
The electrons which in co-valent bond stay static at 0K temperature. Thus reacts as an insulators.
At room temperature, crystal atom contains thermal oscillations. For thus reason some co-valent bond breaks and electron is now a free electron and participating in electric current. Some positive charge create at the place of free electron and it try to catch the other free electron at that place. This empty place is called "Hole".
At these situation we will provide Potential Differene between crystal two ends, the free electrons travels negative side to positive side of battery and produce electric current which shows in Fig.3c.
Fig.3c.
Under effect of the thermal oscillation and external electric field, other free electrons break the co-valent bond and jump in to the hole and creats new holes. For these formation we can say that electrons travels negative sides to positive sides and holes travels positive sides to negative sides.
Thus, Two types of electric current flow in the semiconductor which are as
[1] the motion of free electrons
[2] the motion of free electrons which jumps into the empty holes
Semiconductors have ne and nh which follows free electrons and holes respectively but in intrinsic semiconductor it is equal and it is expressed with ni.
ne=nh=ni
God Bless Thx....
