# Invalid expression. Check for missing multiplication operator, missing or

4 views (last 30 days)
Filip Vucak on 19 Jul 2021
Answered: Walter Roberson on 20 Jul 2021
clear all
close all
clc
%Constants
q=l.6e-19;
k=8.625e-5;
e0=8.854e-14;
%Device, Material, and System Parameters
ni=l.5e10;
esi=ll.8;
T=300;
a=l.5e-4;
z=50e-4;
L=5e-4;
ND=2el5;
VG=[0 -.5 -1 -1.5 -2];
%Contact Potential
V0=.55+k*T*log(ND/ni);
%mobility calculation
NDref=1.3el7;
mu_n_min=92;
mu_n_0=1268;
alpha_n=0.91;
mun=mu_n_min+mu_n_0./(1+(ND/NDref).^alpha_n)
%Resistivity
sigma=q*ND*mun;
rho=l/sigma;
%Mutual Transconductance
G0=2*a*z/(rho*L)
%Pinch—off voltage
VP=V0-q*a^2*ND/(2*e0*esi)
% Calculate ID as a function of VD
VD=linspace(0,abs(VP)+5,100);
for j=1:1:length(VG)
for i=1:1:length(VD)
if VD(i)<(VG(j)-VP) %Linear regime
ID(j,i)=G0*(VD(i)-2/3*(V0-VP)*(((VD(i)+V0-VG(j))/(V0-VP)).^(3/2)-((V0-VG(j))/(V0-VP)).^(3/2)));
else
VD(i)=VG(j)-VP;
ID(j,i)=G0*(VD(i)-2/3*(V0-VP)*(1-((V0-VG(j))/(V0-VP)).^(3/2)));
end
end
end
VD=linspace(0,abs(VP)+5,100); %Voltage vector re—generation for plotting
plot(VD,ID*le6)
hold on
xlabel ('VD (Volts)')
ylabel ('ID (Microampere) ')
title('JFET I—V Characteristics')
grid
%Code ends

Image Analyst on 19 Jul 2021
It doesn't like your decimal point. What is it? If I copy and paste your number into the command window, it complains about the decimal point but if I type it in myself directly, it works fine. Maybe you used some sort of higher order unicode decimal point.
Filip Vucak on 20 Jul 2021
Got it, thank you!

Walter Roberson on 20 Jul 2021
q=l.6e-19;
The decimal point is fine, but that is a lower-case L, not a one, before the decimal point.