Exams › GATE › Technical
The source of a silicon b7n-channel MOS transistor has an area of 1 sq mm and a depth of 1 b5m. If the dopant density in the source is $10^{19}\,\text{cm}^{-3}$, the number of holes in the source region with the above volume is approximately
- $10^7$
- 100
- 10
- 0
Correct answer: 0
Solution
For an n-type region, the hole concentration is the minority carrier concentration, given by $p=n_i^2/N_D$. Here $p=(10^{10})^2/10^{19}=10^1\,\text{cm}^{-3}$, and the source volume is $1\,\text{mm}^2\times 1\,\mu\text{m}=10^{-2}\,\text{cm}^2\times 10^{-4}\,\text{cm}=10^{-6}\,\text{cm}^3$. Thus the number of holes is $10\times 10^{-6}=10^{-5}$, which is approximately zero.
Related GATE Technical questions
- The electron and hole concentrations in an intrinsic semiconductor are \(n_i\) per cm\(^3\) at 300 K. Now, if acceptor impurities are introduced with a concentration of \(N_A\) per cm\(^3\) (where \(N_A \gg n_i\)), the electron concentration per cm\(^3\) at 300 K will be
- In a \(p^+n\) junction diode under reverse bias, the magnitude of electric field is maximum at
- Consider a silicon p-n junction at room temperature having the following parameters: Doping on the n-side = $1\times10^{17}\ \text{cm}^{-3}$ Depletion width on the n-side = $0.1\ \mu\text{m}$ Depletion width on the p-side = $1.0\ \mu\text{m}$ Intrinsic carrier concentration = $1.4\times10^{10}\ \text{cm}^{-3}$ Thermal voltage = $26\ \text{mV}$ Permittivity of free space = $8.85\times10^{-14}\ \text{F cm}^{-1}$ Dielectric constant of silicon = 12 The built-in potential of the junction is
- Statement for Linked Answer Questions 52 and 53: The silicon sample with unit cross-sectional area shown below is in thermal equilibrium. The following information is given: $T=300\,\text{K}$, electronic charge $=1.6\times10^{-19}\,\text{C}$, thermal voltage $=26\,\text{mV}$, and electron mobility $=1350\,\text{cm}^2/\text{V-s}$. The magnitude of the electric field at $x=0.5\,\mu\text{m}$ is
- Drift current in semiconductors depends upon
- A Zener diode, when used in voltage stabilization circuits, is biased in
⚔️ Practice GATE Technical free + battle 1v1 →