Semiconductor Electronics Materials Devices and Simple Circuits

31 solved questions from Class 12 Physics, each with the full working. Tap any question to see the step-by-step solution.

• 1 What is the fundamental law or governing principle of 'Semiconductor Electronics Materials Devices and Simple Circuits' in Class 12 Physics? medium MCQ Fundamental Physical Law
• 2 What is the SI unit and dimensional formula for the key physical quantity studied in 'Semiconductor Electronics Materials Devices and Simple Circuits'? medium MCQ SI Units & Dimensional Analysis
• 3 How does the field or potential intensity vary with distance r in 'Semiconductor Electronics Materials Devices and Simple Circuits'? medium MCQ Spatial Distance Dependence
• 4 What is the net flux or circulation integral through a closed surface in 'Semiconductor Electronics Materials Devices and Simple Circuits'? medium MCQ Gauss's Theorem & Boundary Integrals
• 5 Why do field lines in 'Semiconductor Electronics Materials Devices and Simple Circuits' never intersect each other? medium MCQ Field Line Properties
• 6 Consider a silicon p–n junction at zero bias. The n‑side has a donor concentration of 1.0×10^16,cm^-3 and the p‑side has an acceptor concentration of 1.0×10^14,cm^-3. Using ε_si = 11.7,ε_0, ε_0=8.85×10^-14,F/cm and the built‑in potential V_bi = 0.7,V, calculate the total depletion width W. medium 4 marks Depletion width calculation
• 7 Which of the following statements correctly describes the type of semiconductor formed when silicon is doped with boron? easy MCQ 2 marks Doping effect in semiconductors
• 8 Which of the following statements about a silicon diode in reverse bias is correct? A) The depletion region expands. B) The built‑in potential decreases. C) The junction behaves like a resistor. D) The minority carrier concentration increases. medium MCQ 3 marks Reverse bias effect on diode
• 9 A silicon diode operating at 25 °C has a reverse saturation current I_s = 1×10^-15,A and an ideality factor n = 1. Find the forward current when a voltage of 0.8,V is applied. Use the Shockley diode equation I = I_s[exp(V/(nV_T))-1] and take the thermal voltage V_T = 25.85,mV. hard 5 marks Shockley diode equation
• 10 A silicon diode with area (A=1.0 imes10^-4,\text{cm}^2) has donor concentration (N_D=1.0 imes10^16,\text{cm}^{-3}) and acceptor concentration (N_A=1.0 imes10^14,\text{cm}^{-3}). Its built‑in potential is (0.65,\text{V}). Under a reverse bias of (5,\text{V}), calculate the junction capacitance (C). Use (ε_si=11.7,varepsilon_0). hard 4 marks Junction capacitance under reverse bias
• 11 A silicon p–n junction has a donor concentration (N_D=5.0 imes10^15,\text{cm}^{-3}) on the n‑side and an acceptor concentration (N_A=5.0 imes10^13,\text{cm}^{-3}) on the p‑side. The built‑in potential is (V_bi=0.75,\text{V}). Using (ε_si=11.7,varepsilon_0) with (varepsilon_0=8.85 imes10^-14,\text{F/cm}) and (q=1.6 imes10^-19,\text{C}), calculate the total depletion width (W). medium 3 marks Depletion width of a p‑n junction
• 12 A silicon diode has a reverse saturation current (I_s=5 imes10^-17,\text{A}) and an ideality factor (n=1.2). At 300 K, what forward voltage (V) is required to obtain a forward current of (0.1,\text{A}) using the Shockley equation (I=I_s[exp(V/(nV_T))-1]) with (V_T=25.85,\text{mV})? medium 3 marks Shockley diode equation
• 13 When silicon is doped with (2.0 imes10^15) donor atoms per cm(^3), the semiconductor is called ___. easy MCQ 2 marks Doping of silicon to form n‑type
• 14 A silicon p–n junction at 300 K has an acceptor concentration N_A=2×10^16 cm^-3 on the p‑side and a donor concentration N_D=1×10^15 cm^-3 on the n‑side. The intrinsic carrier concentration of silicon at this temperature is n_i=1.5×10^10 cm^-3. Calculate the minority‑carrier concentration of electrons on the p‑side and of holes on the n‑side. medium 2 marks Minority carrier concentration in a p‑n junction
• 15 Silicon is doped with 5×10^15 cm^-3 arsenic atoms. The resulting semiconductor is classified as: easy MCQ 1 mark Doping type of semiconductor
• 16 A phosphorus‑doped silicon wafer has a donor concentration N_D=2×10^17 cm^-3 and a measured resistivity of 0.02 Ω · cm. Assuming electrons are the only significant carriers, determine the electron mobility μ_n. (Take q=1.6×10^-19 C.) medium 2 marks Conductivity and carrier mobility in doped silicon
• 17 A silicon diode at 300 K has a reverse saturation current I_s=2×10^-14 A and an ideality factor n=1. When a forward bias of 0.7 V is applied, the measured forward current is I_F=10 mA. Assuming the minority‑carrier lifetime τ=0.5 μs and a diode cross‑sectional area A=1×10^-4 cm^2, calculate the diffusion capacitance C_D of the diode. (Use V_T=25.85 mV.) hard 3 marks Diffusion capacitance of a forward‑biased diode
• 18 A phosphorus‑doped silicon wafer has donor concentration N_D = 5×10^16 cm^-3 and electron mobility μ_n = 1350 cm^2V^-1s^-1. Assuming holes are negligible, calculate its electrical conductivity σ in Ω^-1cm^-1. Take q = 1.6×10^-19 C. medium 2 marks Conductivity of extrinsic semiconductor
• 19 A silicon diode at 300 K has cross‑sectional area A = 2×10^-4 cm^2, minority carrier lifetime τ = 1.0 μs, and diffusion coefficient for holes D_p = 12 cm^2s^-1. Under a forward bias of 0.6 V, the forward current measured is I_F = 5 mA. Assuming ideality factor n=1, calculate the diffusion capacitance C_D of the diode using C_D = (I_F τ)/V_T, where V_T = 25.85 mV. hard 3 marks Diffusion capacitance of a forward‑biased diode
• 20 A silicon p–n junction at 300 K has N_A = 1×10^17 cm^-3 on the p‑side and N_D = 5×10^15 cm^-3 on the n‑side. The relative permittivity of silicon is 11.7 and ε_0 = 8.85×10^-14 F/cm. The built‑in potential is V_bi=0.78 V. (a) Find the total depletion width W. (b) If a reverse bias of 10 V is applied, compute the junction capacitance per unit area C' = ε_s / W_R, where W_R = W√(1+V_R/V_bi). Give C' in μF/cm^2. hard 5 marks Depletion width and junction capacitance
• 21 A silicon p‑n junction has an acceptor concentration N_A=1×10^18 cm^-3 on the p‑side and a donor concentration N_D=1×10^16 cm^-3 on the n‑side. The relative permittivity of silicon is ε_r=11.7, ε_0=8.85×10^-14 F/cm, the built‑in potential V_bi=0.85 V and a reverse bias V_R=20 V is applied. (a) Find the total depletion width W (in μm). (b) Determine the junction capacitance per unit area C' = ε_s/W (in μF/cm^2). hard 4 marks Depletion width and junction capacitance
• 22 A silicon wafer is n‑type with donor concentration N_D = 3×10^15 cm^-3 and electron mobility μ_n = 1400 cm^2V^-1s^-1. Assuming holes are negligible, calculate the resistivity ρ of the wafer in Ω · cm. (Take q = 1.6×10^-19 C) easy 1 mark Resistivity and conductivity
• 23 A silicon p‑n junction at 300 K has an acceptor concentration N_A=5×10^16 cm^-3 on the p‑side and a donor concentration N_D=2×10^15 cm^-3 on the n‑side. The intrinsic carrier concentration of silicon at this temperature is n_i=1.5×10^10 cm^-3. Calculate (a) the minority‑electron concentration on the p‑side and (b) the minority‑hole concentration on the n‑side. hard 3 marks Mass‑action law (minority carrier concentration)
• 24 When silicon is doped with 2×10^19 cm^-3 boron atoms, the resulting semiconductor is best described as: medium MCQ 2 marks Doping classification
• 25 A silicon p–n junction at 300,K has an acceptor concentration N_A=4×10^16,cm^-3 on the p‑side and a donor concentration N_D=1×10^15,cm^-3 on the n‑side. The intrinsic carrier concentration of silicon at this temperature is n_i=1.5×10^10,cm^-3. Calculate (a) the minority‑electron concentration on the p‑side and (b) the minority‑hole concentration on the n‑side. medium 3 marks Minority carrier concentration
• 26 An n‑type silicon wafer has a donor concentration N_D=3×10^15,cm^-3 and electron mobility μ_n=1400,cm^2V^-1s^-1. Assuming holes are negligible, calculate the resistivity ρ of the wafer in Ω!·!cm. (Take q=1.6×10^-19,C) hard 4 marks Resistivity of doped silicon
• 27 A silicon p–n junction has an acceptor concentration N_A=1×10^18,cm^-3 on the p‑side and a donor concentration N_D=1×10^16,cm^-3 on the n‑side. The relative permittivity of silicon is ε_r=11.7, ε_0=8.85×10^-14,F/cm, the built‑in potential V_bi=0.90,V and a reverse bias V_R=10,V is applied. Find (a) the total depletion width W (in μm) and (b) the junction capacitance per unit area C'=ε_s/W (in μF/cm^2). hard 4 marks Depletion width and junction capacitance
• 28 A silicon diode at 300 K has a reverse saturation current I_s=1×10^-13 A and an ideality factor n=1. If a forward current of I=5 mA flows, calculate the required forward voltage V using the Shockley diode equation I = I_s[exp(V/nV_T)-1], where the thermal voltage V_T=25.85 mV. medium 2 marks Shockley diode equation
• 29 A silicon wafer is n‑type with donor concentration N_D = 2×10^16 cm^-3 and electron mobility μ_n = 1500 cm^2V^-1s^-1. Assuming holes are negligible, calculate the electrical conductivity σ of the wafer in Ω^-1cm^-1. (Take q = 1.6×10^-19 C) easy 1 mark Conductivity of doped semiconductor
• 30 Silicon is doped with 5×10^19 cm^-3 arsenic atoms. The resulting semiconductor is classified as: medium MCQ 1 mark Classification of doped silicon
• 31 A silicon p–n junction has acceptor concentration N_A=5×10^17 cm^-3 on the p‑side and donor concentration N_D=1×10^15 cm^-3 on the n‑side. The relative permittivity of silicon is ε_r=11.7, ε_0=8.85×10^-14 F/cm, the built‑in potential V_bi=0.85 V and a reverse bias V_R=15 V is applied. (a) Find the total depletion width W in μm. (b) Determine the junction capacitance per unit area C' = ε_s/W in μF/cm^2. (Take q=1.6×10^-19 C) hard 3 marks Depletion width and junction capacitance