simulate a npn BJT with PC1D

We want to simulate a n-p-n BJT with PC1D. 

1. Use an n-type Si wafer with an area of 1 mm2, 2. a thickness of 5 μm, 3. a background doping of 1×1015 cm-3. 

Commonly the base and emitter are formed by diffusion processes. 

1. The base diffusion has a Gaussian profile with a depth factor of 0.2 μm and a peak 

doping of 1×1018 cm-3 (1st front diffusion). 2. The emitter diffusion has an erfc profile with a depth factor of 0.1 μm and a peak doping 

of 1×1020 cm-3 (2nd front diffusion). 3. Further assume a lifetime of 0.05 μs and surface recombination velocities of 1000 cm/s. 4. Enable all contacts and set the emitter and base internal series resistances to 1×10-6 Ω 

and the collector series resistance to 0.1 Ω. 5. The base contact should be at 0.35 μm from the front surface. 

Excitation/Simulation: 

1. The excitation should be transient with 86 time steps and a time step size of 0.5 s. 2. Set the first time step at t = 0 to 1×10-9. 3. For the base circuit load the external file (located in the PC1D main folder) ib.vlt and 

for the collector circuit vce.vlb. 

This will create a family of common-emitter curves. The curves for collector current correspond to 0.1, 0.2, 0.3 and 0.4 mA of base current, while the collector-emitter voltage is scanned in a range between 0 and 5 Volts. 

Deliverables (10 points each): 

1. Simulate the collector current vs. collector-emitter voltage characteristics. (print this) 

2. Determine the common-emitter current gain β. (Show calculations) 

3. Determine the emitter efficiency, assuming the base transport factor is unity (1.0). (show 

calculations) 

4. What happens to β if the base diffusion is too deep (depth factor of 0.5 μm). Explain the 

behavior. 

5. What happens to β if the emitter doping is too low (peak doping of 5×1018 cm-3). Explain the 

behavior.