# Contact potential versus temperature

Discussion in 'Homework Help' started by xxxyyyba, Nov 13, 2013.

1. ### xxxyyyba Thread Starter Member

Aug 7, 2012
249
2
Hi!
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?

Last edited: Nov 17, 2013
2. ### wayneh Expert

Sep 9, 2010
12,090
3,027
You tell us. What does you plot look like?

3. ### xxxyyyba Thread Starter Member

Aug 7, 2012
249
2
If I knew I wouldn't ask
EDIT: In expression for Vcpaprox term niaprox should be squared

4. ### WBahn Moderator

Mar 31, 2012
17,715
4,788
You don't know what your plot looks like?

5. ### xxxyyyba Thread Starter Member

Aug 7, 2012
249
2
My previous post is related to wayneh's first sentence
There is mistake in code?

6. ### shteii01 AAC Fanatic!

Feb 19, 2010
3,378
494
There is a couple mistakes, the mistakes that I noticed were syntax mistakes, missing parenthesis, that sort of things.

7. ### xxxyyyba Thread Starter Member

Aug 7, 2012
249
2
I'll be thankful if you reveal me mistakes.

8. ### shteii01 AAC Fanatic!

Feb 19, 2010
3,378
494
xxxyyyba likes this.
9. ### xxxyyyba Thread Starter Member

Aug 7, 2012
249
2
Everything else is fine?