Hi!
Here is my task:
Concentration of donor atoms on N side is Nd=10^17 cm^(-3) and concentration of acceptor atoms on P side is 2*10^15 cm^(-3). Construct a plot in Matlab of contact potential versus temperature, on same graph, for these models:
Eg(T)=Eg0, Eg(T)=Eg0-a*T and Eg(T)=Eg0-(alfa*T^2)/(beta+T).
k=8.62*10^(-15)eV, Eg0=0.785eV, alfa=7.02*10^(-4) eV/K, beta=1108K, a=3.66*10^(-4) eV/K, C=1.76*10^16.

Here is my code:
T=1:800;
Na=2*10^15;
Nd=10^17;
k1=1.38*10^(-23);
k=8.62*10^(-5);
C=1.76*10^16;
alfa=7.02*10^(-4);
beta=1108;
a=3.66*10^(-4);
q=1.602*10^(-19);
Eg0=0.785;
Egtlinearni=Eg0-a.*T;
Egtnelinearni=Eg0-(alfa.*T.^2)./(beta+T);
Egtpriblizno=Eg0;
figure
nilinearni=sqrt(C.*T.^3.*exp(-Egtlinearni./(k.*T)));
ninelinearni=sqrt(C.*T.^3.*exp(-Egtnelinearni./(k.*T)));
nipriblizno=sqrt(C.*T.^3.*exp(-Egtpriblizno./(k.*T)));
Vcplinearni=(k1.*T./q).*log((Na.*Nd)./(nilinearni.^2));
Vcpnelinearni=(k1.*T./q).*log((Na.*Nd)./(ninelinearni.^2));
Vcppriblizno=(k1.*T./q).*log((Na.*Nd)./(nipriblizno.^2));
plot(T,Vcplinearni,T,Vcpnelinearni,'.',T,Vcppriblizno,'--')
grid
xlabel T
ylabel Vcp
legend('Eg(T)=Eg0-a*T','Eg(t)=Eg0-(alfa*T^2)/(beta+T)','Eg(t)=Eg0')

Is it ok?

 

Is it ok?

You tell us. What does you plot look like?

 

If I knew I wouldn't ask
EDIT: In expression for Vcpaprox term niaprox should be squared

 

You don't know what your plot looks like?

 

My previous post is related to wayneh's first sentence
There is mistake in code?

 

There is a couple mistakes, the mistakes that I noticed were syntax mistakes, missing parenthesis, that sort of things.

 

I'll be thankful if you reveal me mistakes.

 

I'll be thankful if you reveal me mistakes.

xlabel, ylabel http://www.mathworks.com/help/matlab/ref/xlabel.html

 

Everything else is fine?