2. A Si sample in thermal equilibrium at 300 K is doped with 1 x $10^{19}$ phosphorus atoms. Determine
the conductivity of this sample.
3. A sample of Si in thermal equilibrium at 350 K is doped with 2 x $10^{15}$ cm$^3$ boron atoms.
a) Calculate $N_c$, $N_v$ and $n_i$ for this sample.
b) Determine $E_f - E_v$ in this sample.
c) What is the minority carrier concentration?
d) Find $E_{c_i} - E_f$ in this sample.
e) What is the probability an energy state at $E_c$ is occupied by an electron in this sample?
f) Sketch the band diagram for this sample showing the numerical values for $E_f - E_v$, $E_c - E_f$ and
$E_g$
4. a) Sketch the band diagram for a typical unbiased pn junction at thermal equilibrium. Label the
following on the diagram; p-side and n-side of the junction, conduction and valence bands,
metallurgical layer, $E_c$, $E_{fin}$, $E_{rip}$, $E_{rn}$, $E_{rp}$, + and - space charges, W, $X_n$, $X_p$ and $eV_{bi}$.
b) Describe the predominant carrier transport mechanism which produces the current in a pn
junction under forward bias.
c) Describe the predominant carrier transport mechanism which produces the current in a pn
junction under reverse bias.
