7 files changed, 107 insertions, 0 deletions
diff --git a/273/CH18/EX18.2/ex18_2.sce b/273/CH18/EX18.2/ex18_2.sce
new file mode 100755
index 000000000..04ec65195
--- /dev/null
+++ b/273/CH18/EX18.2/ex18_2.sce
@@ -0,0 +1,13 @@
+clc;clear;
+//Example 18.2
+//calculation of probability
+
+//given values
+T=300;//temp in K
+kT=.026;//temperture equivalent at room temp in eV
+Eg=5.6;//forbidden gap in eV
+
+//calculation
+f=1/(1+%e^(Eg/(2*kT)));
+
+disp(f,'probability of an e being thermally promoted to conduction band is');
diff --git a/273/CH18/EX18.3/ex18_3.sce b/273/CH18/EX18.3/ex18_3.sce
new file mode 100755
index 000000000..ab7d198de
--- /dev/null
+++ b/273/CH18/EX18.3/ex18_3.sce
@@ -0,0 +1,18 @@
+clc;clear;
+//Example 18.3
+//calculation of fraction of e in CB
+
+//given values
+T=300;//temp in K
+kT=.026;//temperture equivalent at room temp in eV
+Eg1=.72;//forbidden gap of germanium in eV
+Eg2=1.1;//forbidden gap of silicon in eV
+Eg3=5.6;//forbidden gap of diamond in eV
+
+//calculation
+f1=%e^(-Eg1/(2*kT));
+disp(f1,'fraction of e in  conduction band of germanium is');
+f2=%e^(-Eg2/(2*kT));
+disp(f2,'fraction of e in  conduction band of silicon is');
+f3=%e^(-Eg3/(2*kT));
+disp(f3,'fraction of e in  conduction band of diamond  is');
diff --git a/273/CH18/EX18.4/ex18_4.sce b/273/CH18/EX18.4/ex18_4.sce
new file mode 100755
index 000000000..3344e2c6b
--- /dev/null
+++ b/273/CH18/EX18.4/ex18_4.sce
@@ -0,0 +1,15 @@
+clc;clear;
+//Example 18.3
+//calculation of fractionional change in no of e
+
+//given values
+T1=300;//temp in K
+T2=310;//temp in K
+Eg=1.1;//forbidden gap of silicon in eV
+k=8.6*10^-5;//boltzmann's constant in eV/K
+
+//calculation
+n1=(10^21.7)*(T1^(3/2))*10^(-2500*Eg/T1);//no of conduction e at T1
+n2=(10^21.7)*(T2^(3/2))*10^(-2500*Eg/T2);//no of conduction e at T2
+x=n2/n1;
+disp(x,'fractional change in no of e is');
+\ No newline at end of file
diff --git a/273/CH18/EX18.5/ex18_5.sce b/273/CH18/EX18.5/ex18_5.sce
new file mode 100755
index 000000000..186b145d0
--- /dev/null
+++ b/273/CH18/EX18.5/ex18_5.sce
@@ -0,0 +1,15 @@
+clc;clear;
+//Example 18.5
+//calculation of resistivity
+
+//given values
+e=1.6*10^-19;
+ni=2.5*10^19;//intrinsic density of carriers per m^3
+ue=.39;//mobility of e 
+uh=.19;//mobility of hole
+
+
+//calculation
+c=e*ni*(ue+uh);//conductivity
+r=1/c;//resistivity
+disp(r,'resistivity in ohm m is');
+\ No newline at end of file
diff --git a/273/CH18/EX18.6/ex18_6.sce b/273/CH18/EX18.6/ex18_6.sce
new file mode 100755
index 000000000..9569dc1e1
--- /dev/null
+++ b/273/CH18/EX18.6/ex18_6.sce
@@ -0,0 +1,16 @@
+clc;clear;
+//Example 18.6
+//calculation of conductivity of intrinsic and doped semiconductors
+
+//given values
+h=4.52*10^24;//no of holes per m^3
+e=1.25*10^14;//no of electrons per m^3
+ue=.38;//e mobility
+uh=.18;//hole mobility
+q=1.6*10^-19;//charge of e in C
+//calculation
+ni=sqrt(h*e);//intrinsic concentration
+ci=q*ni*(ue+uh);
+disp(ci,'conductivity of semiconductor(in S/m) is');
+cp=q*h*uh;
+disp(cp,'conductivity of doped semiconductor (in S/m) is');
+\ No newline at end of file
diff --git a/273/CH18/EX18.7/ex18_7.sce b/273/CH18/EX18.7/ex18_7.sce
new file mode 100755
index 000000000..fb75eadbd
--- /dev/null
+++ b/273/CH18/EX18.7/ex18_7.sce
@@ -0,0 +1,14 @@
+clc;clear;
+//Example 18.7
+//calculation of hole concentration
+
+//given values
+ni=2.4*10^19;//carrier concentration per m^3
+N=4*10^28;//concentration of ge atoms per m^3
+
+//calculation
+ND=N/10^6;//donor cocntrtn
+n=ND;//no of electrones
+
+p=ni^2/n;
+disp(p,'concentartion of holes per m^3 is');
+\ No newline at end of file
diff --git a/273/CH18/EX18.8/ex18_8.sce b/273/CH18/EX18.8/ex18_8.sce
new file mode 100755
index 000000000..85ddf7ab7
--- /dev/null
+++ b/273/CH18/EX18.8/ex18_8.sce
@@ -0,0 +1,16 @@
+clc;clear;
+//Example 18.8
+//calculation of Hall voltage
+
+//given values
+ND=10^21;//donor density per m^3
+B=.5;//magnetic field in T
+J=500;//current density in A/m^2
+w=3*10^-3;//width in m
+e=1.6*10^-19;//charge in C
+
+//calculation
+
+
+V=B*J*w/(ND*e);//in volts
+disp(V*10^3,'Hall voltage in mv is');
+\ No newline at end of file