Problem in simulating if condition

When I am trying to simulate , it is only taking one codition. The other condition it is not taking.

gd=2;

Ecd=0.045;

k=8.617e-5;

ni=1e10;

T=linspace(0,600,100);

mee=0.553*9.11e-31;

meh=0.357*9.11e-31;

Nc=((2.510e19)*((0.553)^1.5).*((T/300).^1.5));

Nv=((2.510e19)*((0.357)^1.5).*((T/300).^1.5));

display(Nc)

display(Nv)

Nj=(Nc/gd).*(exp(-Ecd./(k.*T)));

display(Nj)

Nd=1e15;

Eg0=0.7437;

a=4.77e-4;

b=235;

Eg=Eg0-((a*(T.^2))./(T+b));

display(Eg)

ni=((sqrt(Nc.*Nv)).*(exp((-Eg)./(2*k.*T))));

if (T>300)

n=(Nd/2)+(sqrt(((Nd/2)^2)+(ni.^2)));

else

n=((Nj/2).*((sqrt(1+((4*Nd)./(Nj))))-1));

end

plot(T,n/Nd,'g','linewidth',2)

plot(T, ni/Nd,'--r','linewidth',2)

grid on

xlabel('Temperature in K')

ylabel('n/Nd')

title('Temp. dependence of Majority Carrier Concentration')

set(gca,'ylim',[0 3],'xlim', [0 610])

[SWASTIK SAHOO]

I am not getting the curve where it is increasing with temperature. I am only getting saturated value..

Thank you so much for your help.

gd=2;

Ecd=0.045;

k=8.617e-5;

ni=1e10;

T=linspace(0,600,100);

mee=0.553*9.11e-31;

meh=0.357*9.11e-31;

Nc=((2.510e19)*((0.553)^1.5).*((T/300).^1.5));

Nv=((2.510e19)*((0.357)^1.5).*((T/300).^1.5));

display(Nc)

display(Nv)

Nj=(Nc/gd).*(exp(-Ecd./(k.*T)));

display(Nj)

Nd=1e15;

Eg0=0.7437;

a=4.77e-4;

b=235;

Eg=Eg0-((a*(T.^2))./(T+b));

display(Eg)

ni=((sqrt(Nc.*Nv)).*(exp((-Eg)./(2*k.*T))));

if (T>300)

n=(Nd/2)+(sqrt(((Nd/2)^2)+ni.^2));

else

n=((Nj/2).*((sqrt(1+((4*Nd)./(Nj))))-1));

end

plot(T,n/Nd,'b','linewidth',2)

%plot(T,n1/Nd,'b','linewidth',2)

display(n)

display(n/Nd)

display(ni/Nd)

%plot(T,n/Nd,'b','linewidth',2)

hold on

plot(T, ni/Nd,'--r','linewidth',2)

%plot(T,n1/Nd,'b','linewidth',2)

hold off

grid on

xlabel('Temperature in K')

ylabel('n/Nd')

title('Temp. dependence of Majority Carrier Concentration')

set(gca,'ylim',[0 3],'xlim', [0 610])

legend('n/Nd', 'ni/Nd')

[Alan Stevens]

I was too quick off the mark. You were right, your "if" functions don't work properly! See below.

Answer 1

[Alan Stevens]

You can replace your if statement with

% Assuming there are 100 steps in T
nhi=(Nd/2)+(sqrt(((Nd/2)^2)+(ni(51:100).^2)));
nlo=((Nj(1:50)/2).*((sqrt(1+((4*Nd)./(Nj(1:50)))))-1));
n = [nlo, nhi];

Also replace

plot(T,n/Nd,'g','linewidth',2)
plot(T, ni/Nd,'--r','linewidth',2)

with

plot(T,n/Nd,'g','linewidth',2)
hold on
plot(T, ni/Nd,'--r','linewidth',2)

if you want both curves on the same plot.

The following is the result

[SWASTIK SAHOO]

Do I need to prespecify nhi, nlo???It is showing Unrecognized variable or function "nhi"

[Alan Stevens]

Like so:

gd=2;
Ecd=0.045;
k=8.617e-5;
%
%ni=1e10;
T=linspace(0,600,100);
mee=0.553*9.11e-31;
meh=0.357*9.11e-31;
Nc=((2.510e19)*((0.553)^1.5).*((T/300).^1.5));
Nv=((2.510e19)*((0.357)^1.5).*((T/300).^1.5));
% display(Nc);
% display(Nv);
Nj=(Nc/gd).*(exp(-Ecd./(k.*T)));
% display(Nj);
Nd=1e15;
Eg0=0.7437;
a=4.77e-4;
b=235;
Eg=Eg0-((a*(T.^2))./(T+b));
% display(Eg);
ni=((sqrt(Nc.*Nv)).*(exp((-Eg)./(2*k.*T))));

% Assuming there are 100 steps in T
nhi=(Nd/2)+(sqrt(((Nd/2)^2)+(ni(51:100).^2)));
nlo=((Nj(1:50)/2).*((sqrt(1+((4*Nd)./(Nj(1:50)))))-1));
n = [nlo, nhi];

plot(T,n/Nd,'g','linewidth',2)
hold on
plot(T, ni/Nd,'--r','linewidth',2)
grid on
xlabel('Temperature in K')
ylabel('n/Nd')
title('Temp. dependence of Majority Carrier Concentration')
set(gca,'ylim',[0 3],'xlim', [0 610])