9402934383

£kk:- 10/io/iS

fl PROGRAM- 04

OBJBCT: Program to calculate

and plot the depletion width vs impurity

exercise

concentration (NA ^ ^{dep,etion widlh} (^w) ^{versus the ,m}P^uritY junctions maintained at 300.!^    ^ ^d°^{Ped Side} °^{f si} P ^{ł n and} " ^ł P ^st*P

covering the rangę 10 _4/cl «    ^ ^VA = ⁰ 5 v- ⁰ v- ^a"^d 10 V

' ^/cm3 a _{JVA or WD <} 10|7/cm3

THEORY

: The V# associated with the p+-n and n+-p step junctions is computed using the relationship established. Also, with the junction asymmetrically doped, the doping factor for W simplifies.

CODĘ

%Constants and Parameters T=300;    % Temperaturę in Kelvin

k=8.617e-5;    % Boltzmann constant (eV/K)

e0=8.85e-14; % permittivity of free space (F/cm) q=1.602e-19; % charge of an electron (coulomb)

KS=11.8; % dielectric constant of Si at 300K

ni=lelO; % intrinsic carrier conc. in Silicon at 300K (cm^A-3)

EG=1.12;    % band gap of Silicon (eV)

%Choose variable values

NB=logspace(14,17); % doping ranges from lel4 to lel7 VA=( 0.5 0 -10 ];    % VA values set

%Depletion width calculation

Vbi=EG/2+k*T.*log(NB./ni);

W(l,:)=1.0e4*sqrt(2*KS*e0/q.*(Vbi-VA(l))./NB); W(2_/:)=1.0e4*sqrt(2*KS*e0/q.*(Vbi-VA(2))./NB); W(3,:)=1.0e4*sqrt(2*KS*e0/q.*(Vbi-VA(3))./NB);

%Plot

close

loglog(NB, W/-*)

axis([1.0el4 1.0el7 1.0e-l l.Oel]) grid

xlabel('NA or ND (cm^A-3)')

Ylabel('W (micrometers)')