Recent questions tagged semiconductor-electronics

Selenium (Se) is a group VI element (i.e. two columns to the right of Silicon on the periodic table). An extrinsic semiconductor is produced by doping Silicon (Si) with 1020 Selenium atoms per m3. Assuming saturation, calculate the conductivity of the extrinsic semiconductor.

asked Jul 13, 2014 by balaji.thirumalai

1 answer

Given $n_i = 2.4 \times 10^{19} m^{-3}, \; \mu_n = 0.39\;m^2/V.S, \; \mu_p = 0.19\;m^2/V.s$ for intrinsic Ge at room temperature of $300^{\circ}\;K$, calculate the conductivity of the sample.

asked Jul 13, 2014 by balaji.thirumalai

1 answer

Estimate the conductivity ($\sigma_i$) and resistivity ($\rho_i$) of silicon atoms and electron-hole pairs at room temperature of $300^{\circ}\;K$ if every 10-millionth silicon atom is replaced by an atom of Indium.

asked Jul 13, 2014 by balaji.thirumalai

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Estimate the intrinsic conductivity ($\sigma_i$) and resistivity ($\rho_i$) of silicon atoms and electron-hole pairs at room temperature of $300^{\circ}\;K$.

asked Jul 13, 2014 by balaji.thirumalai

1 answer

C, Si and Ge atoms have 4 Valence electrons each. Their valence and conduction bands are separated by energy band gaps represented by $E_C, E_{Si}, E_{Ge}$ respectively. Which of the following relationship is true in their case?

asked Jul 13, 2014 by balaji.thirumalai

1 answer

Which of the following statements about intrinsic semiconductors are incorrect?

asked Jul 13, 2014 by balaji.thirumalai

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Suppose a pure Si crystal has $5 \times 10^{28} \text{atoms} / m^3$. It is doped by 1 ppm concentration of pentavalent As. Calculate the number of electrons and holes, given that $n_i = 1.5 \times 10^{16} \;/m^3$

asked Jul 13, 2014 by balaji.thirumalai

1 answer

A semiconductor has an electron concentration of $0.45 \times 10^{22} \; /m^3$ and a hole concentration of $5 \times 10^{20} \;/ m^3$. Find its conductivity.

asked Jul 13, 2014 by balaji.thirumalai

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A p type semiconductor has acceptor level of 57 mev above the valance band. Find the maximum wave length of light which can create a hole.

asked Jul 13, 2014 by balaji.thirumalai

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Given that logic Gates can be represented as Venn Diagrams, match the following:

asked Jul 13, 2014 by balaji.thirumalai

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Evaluate the correct Boolean Expression for the given circuit?

asked Jul 13, 2014 by balaji.thirumalai

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Evaluate the correct Boolean Expression for the given circuit?

asked Jul 13, 2014 by balaji.thirumalai

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Evaluate the correct Boolean Expression for the given circuit?

asked Jul 13, 2014 by balaji.thirumalai

1 answer

In the circuit given below the value of current is :

asked Jan 31, 2014 by meena.p

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A transistor is connected in common emitter mode. In the collector circuit the voltage drop across the resistor of $800 \; \Omega$ is $0.5 V$ . If current gain $\alpha$ is $0.96$ What is base current

asked Jan 31, 2014 by meena.p

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When forward bias is applied to a p-n junction.

asked Jan 31, 2014 by meena.p

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The graph given below represents the I-V characteristics of a zener diode. Which part of the curve is relevant for operation as voltage regulator?

asked Jan 31, 2014 by meena.p

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A Diode Laser

asked Jan 31, 2014 by meena.p

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To make a full wave rectifier using these four diodes, the ac input should be applied across what?

asked Jan 31, 2014 by meena.p

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When a solid with a band gap has a donor level just below its empty energy band, its solid is

asked Jan 31, 2014 by meena.p

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Which of the following logic gate is an universal gate

asked Jan 31, 2014 by meena.p

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In Boolean Algebra what is value of $A.B+A.C.B$

asked Jan 31, 2014 by meena.p

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Using law of Boolean Algebra the value of $A+(\bar {A}B)$

asked Jan 31, 2014 by meena.p

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In half wave rectifier if the D.C component at output is $\large\frac{10}{\pi} $$V$ What is the peak value of sinusoidal input signal.

asked Jan 31, 2014 by meena.p

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Transistor working as an amplifier operates in its active region of characteristic only when

asked Jan 31, 2014 by meena.p

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In the circuit given below if the output $D=1$ the input must be

asked Jan 31, 2014 by meena.p

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which of the following represents the system of logic gates given below.

asked Jan 31, 2014 by meena.p

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If the 0 and 1 are inputs for a NAND gate what would be the output?

asked Jan 30, 2014 by meena.p

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The following circuit can be reduced to what type of a gate?

asked Jan 30, 2014 by meena.p

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Which of the statement about NOT gate is true?

asked Jan 30, 2014 by meena.p

1 answer

The following logic circuit has output

asked Jan 30, 2014 by meena.p

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Three NAND gates are connected as shown in circuit. The logic operation corresponds to

asked Jan 30, 2014 by meena.p

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Given the following VI-Characteristic curve of a pn-junction diode, identify what is (A) and (B)?

asked Jan 30, 2014 by meena.p

1 answer

The figure shows two capacitors of capacitance c and charged to same potential c connected in two circuits . What will be the charge on the capacitor after a time $t= cr$ from the start

asked Jan 30, 2014 by meena.p

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The output of the circuit across resistor R is

asked Jan 30, 2014 by meena.p

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The circuit given below represents

asked Jan 30, 2014 by meena.p

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In the circuit shown below two inputs A and B and output C is given. The circuit represents

asked Jan 30, 2014 by meena.p

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The Output Y of the figure is :

asked Jan 30, 2014 by meena.p

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The figure represents

asked Jan 30, 2014 by meena.p

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The Boolean equation for the circuit is

asked Jan 30, 2014 by meena.p

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The following figure has two NOT gates and a NOR. What does it represent?

asked Jan 29, 2014 by meena.p

1 answer

Which of the gate is represented by

asked Jan 29, 2014 by meena.p

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How many NAND gates are used to form an AND gate

asked Jan 29, 2014 by meena.p

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Truth table given below represents

asked Jan 28, 2014 by meena.p

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The following logic symbol represents

asked Jan 28, 2014 by meena.p

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For a given transistor, the value of the forward transfer ratio $\beta =50$. Calculatethe ratio of change in collector current to the change in emitter current.

asked Jan 28, 2014 by meena.p

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WHich of the following best describes the output of a full wave rectifier:

asked Jan 28, 2014 by meena.p

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The emitter current in a transistor is $ 1mA$ If $\alpha =0.95$ value of base current is :

asked Jan 28, 2014 by meena.p

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The transconductance of a transistor used as an amplifier in common emitter mode is $0.1 \;mho.$ When a signal of 10 mv is added to base emitter voltage change in collector current is

asked Jan 28, 2014 by meena.p

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Given $\Delta V_{BE} = $ potential difference across base emitter, $\Delta I_C = $ change in collector current, $\Delta I_B = $ change in the base current and $\Delta R_{BE} = $ change in base emitter resistance, which of the following best represents transconductance $g_m$.

asked Jan 28, 2014 by meena.p

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