Basics Of Semiconductor Physics

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What is the difference between direct band gap and indirect band gap semiconductors? In one line In a direct band gap semiconductor the conduction band minimum and valence band maximum occur at the same crystal momentum k , s... Basics Of Semiconductor Physics 1 answer
How is the electrical conductivity of an intrinsic and extrinsic semiconductor expressed? In one line The conductivity of a semiconductor is σ = e(nμ_e + pμ_h) , the sum of contributions from electrons and holes; for intrinsic mat... Basics Of Semiconductor Physics 1 answer
What is drift velocity of charge carriers and how is it related to current? In one line Drift velocity is the small average velocity that free electrons (or holes) acquire in the direction set by an applied electric... Basics Of Semiconductor Physics 1 answer
What is mobility of charge carriers and what factors affect it? In one line Mobility is the drift velocity acquired by a charge carrier per unit electric field, μ = v_d/E , and it measures how easily carr... Basics Of Semiconductor Physics 1 answer
How is the electrical conductivity of a metallic conductor derived in terms of drift velocity and mobility? In one line In a metal the current density is J = nev_d = neμ E , so conductivity is σ = neμ = ne²τ/m , set by the free-electron density and... Basics Of Semiconductor Physics 1 answer
What is the Fermi-Dirac distribution function and how does it behave at different temperatures? In one line The Fermi-Dirac distribution function f(E) = 1/(1 + e^((E - E_F)/kT)) gives the probability that an electron energy state E is o... Basics Of Semiconductor Physics 1 answer
Why does the Fermi level lie at the middle of the band gap in an intrinsic semiconductor? In one line In an intrinsic semiconductor the number of electrons in the conduction band equals the number of holes in the valence band, and... Basics Of Semiconductor Physics 1 answer
Where does the Fermi level lie in n-type and p-type extrinsic semiconductors, and why? In one line In an n-type semiconductor the Fermi level lies close to the conduction band (between the donor level and E_c at 0 K), and in a... Basics Of Semiconductor Physics 1 answer
How does the Fermi level in extrinsic semiconductors shift with temperature and doping concentration? In one line As temperature rises, the Fermi level of both n-type and p-type semiconductors moves towards the middle of the gap (the material... Basics Of Semiconductor Physics 1 answer
Explain mobility of electrons. The resistivity of Cu is 1.72 x 10-8 ohm-m. Calculate the mobility of electrons in Cu given that number of electrons per unit volume is 10.41 x 1028 m-3. Mobility (μ): When an electric field E is applied, free electrons acquire a drift velocity v_d proportional to E. Mobility is the drift velo... Basics Of Semiconductor Physics 1 answer
Derive an expression for Fermi level for an intrinsic semiconductor. In an intrinsic semiconductor, the electron concentration in the conduction band is n=N_c e^(-(E_c-E_F)/kT) and the hole concentration in th... Basics Of Semiconductor Physics 1 answer
Write Fermi- Dirac distribution function and explain the terms in it. The Fermi–Dirac distribution function gives the probability that an available energy state E is occupied by an electron at absolute temperat... Basics Of Semiconductor Physics 1 answer
Define drift velocity and Mobility. Write its unit. Drift velocity ( v_d ): When an electric field is applied to a conductor or semiconductor, the free charge carriers acquire a small average... Basics Of Semiconductor Physics 1 answer
Show that the intrinsic Fermi level lies in the middle of the band gap. In an intrinsic semiconductor, the electron concentration in the conduction band is n=N_c e^(-(E_c-E_F)/kT) and the hole concentration in th... Basics Of Semiconductor Physics 1 answer
Calculate electron and hole concentration in intrinsic silicon at room temperature if its electric conductivity is 4x10-4 mho/m. Given that mobility of electron is 0.14 m2/V-Sec mobility of holes is 0.04 m2/V-Sec. Given: σ_i=4×10⁻⁴ mho/m, μ_e=0.14 m²/V s, μ_h=0.04 m²/V s. Formula: For an intrinsic semiconductor, n=p=n_i and σ_i=n_ie(μ_e+μ_h) . n_i=σ_i/... Basics Of Semiconductor Physics 1 answer
Write Fermi Dirac distribution function and explain the terms involved in it The Fermi–Dirac distribution function gives the probability that an available energy state E is occupied by an electron at absolute temperat... Basics Of Semiconductor Physics 1 answer
Predict the effect on the electrical properties of a silicon at room temperature if every millionth silicon atom is replaced by an atom of indium. Given: Concentration of silicon atoms are 5 x 1028 /m3, intrinsic conductivity of silicon is 4.4 x 10-4… Given: N_Si=5×10²⁸ m ⁻³ , σ_i=4.4×10⁻⁴ (Ω m) ⁻¹ , μ_h=0.048 m²/V s. Indium is trivalent, so it acts as an acceptor. Replacing one Si atom in... Basics Of Semiconductor Physics 1 answer
Show that for an intrinsic semiconductor, fermi level lies midway of conduction band and valence band. In an intrinsic semiconductor, the electron concentration in the conduction band is n=N_c e^(-(E_c-E_F)/kT) and the hole concentration in th... Basics Of Semiconductor Physics 1 answer