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lecture title :red_flag: : Semi Conductor Material (Energy Level Diagram,…

- - - - يمكن أن نحصل عليها بدرجة نقاوة عالية (high degree purification)
      - تتوفر بكمية كبيرة في الطبيعة
      - كلفة استخراجها اقتصادية
    - - doping : Adding impurities (شوائب) to pure semi.c and produce doped semic
    - - compounds
        
        GoAl
        
        GaAS
      - elements
        
        Si
        
        Ge
    - - (Ex : si crystal ) At t=0 k , all electrons are in bond so si is considered as an insulator at t=o k
      - For t>o k ,some electrons gain enough energy (Eg) , break the bond and leave +ve charge (hole)
        A t certain temp No. of electrons = No. of holes= intrinsic carrier concentration (ni)
        
        ni = B. (T)^(3/2).e^(-Eg/2kT)
        Number/cm^3
        ni:No. of electrons /No. of holes
        B: constant depends on material type
        T : temp in kelvin
        k : Boltzman’s constant
        :star: At T=0 , ni=0
        
        for Si at room temp ni = 1.5X10^(10) /cm^3 compared with No. of atoms in cm^3 which is 5X10^(22) atom the above No.(1.5X10^10) is law
        
        To encrease No. of carrier at room temp we have to use doping and reduce doped semic (EXtrinsic semic)