A p-n junction has acceptor impurity concentration of 1017 cm -3 in the P side and donor impurity concentration of 1016 cm -3 in the N side. What is the contact potential at the junction? (k T= thermal energy, intrinsic carrier concentration .ni=1.4 × 1010 cm -3)

Question

A p-n junction has acceptor impurity concentration of 1017 cm -3 in the P side and donor impurity concentration of 1016 cm -3 in the N side. What is the contact potential at the junction? (k T= thermal energy, intrinsic carrier concentration .ni=1.4 × 1010 cm -3) (A) ( kT / e ) ln (4 × 1012) (B) ( kT / e ) ln (2.5 × 1023) (C) (k T / e) ln (1023) (D) ( kT / e ) ln (109)

Tardigrade Admin · Accepted Answer

Constant potential at the junction V text constant (k T/e) ln ((na nd/ni2)) ∴ V text constant =(k T/e) ln ((1017 × 1016/(1.4 × 1010)2)) =(k T/e) ln (4 × 1012)

$(k T / e) ln (4 \times 1 0^{12})$

$(k T / e) ln (2.5 \times 1 0^{23})$

$(k T / e) ln (1 0^{23})$

$(k T / e) ln (1 0^{9})$

Constant potential at the junction
$V_{constant} \frac{k T}{e} ln (\frac{n _{a} n _{d}}{n _{i}^{2}})$
$∴ V_{constant} = \frac{k T}{e} ln (\frac{1 0 ^{17} \times 1 0 ^{16}}{( 1.4 \times 1 0 ^{10} ) ^{2}})$
$= \frac{k T}{e} ln (4 \times 1 0^{12})$

Q. A p−n junction has acceptor impurity concentration of 1017cm−3 in the P side and donor impurity concentration of 1016cm−3 in the N side. What is the contact potential at the junction? (kT= thermal energy, intrinsic carrier concentration ni​=1.4×1010cm−3)

(kT/e)ln(4×1012)

(kT/e)ln(2.5×1023)

(kT/e)ln(1023)

(kT/e)ln(109)

Constant potential at the junction Vconstant ​ekT​ln(ni2​na​nd​​) ∴Vconstant ​=ekT​ln((1.4×1010)21017×1016​) =ekT​ln(4×1012)

$(k T / e) ln (4 \times 1 0^{12})$

$(k T / e) ln (2.5 \times 1 0^{23})$

$(k T / e) ln (1 0^{23})$

$(k T / e) ln (1 0^{9})$

Constant potential at the junction
$V_{constant} \frac{k T}{e} ln (\frac{n _{a} n _{d}}{n _{i}^{2}})$
$∴ V_{constant} = \frac{k T}{e} ln (\frac{1 0 ^{17} \times 1 0 ^{16}}{( 1.4 \times 1 0 ^{10} ) ^{2}})$
$= \frac{k T}{e} ln (4 \times 1 0^{12})$