
			A SIMPLE NPN DEVICE

This is a generic NPN transistor example.  The device is a 3 microns by
1 micron with a single region consisting of silicon.  

The file that defines the mesh for this device is called npn1.p2.  This 
file first generates a grid for the device.  This grid puts more points
near the emitter base and collector bas junctions.  The grid for this 
device is simple, and the number of points are few since this is a small
device.

The electrodes for the emitter, base and collector are then defined.  This
splits the device into 3 sections.  These sections are then doped such that
the NPN transistor is formed.  The emitter is doped n-type with a concen-
tration of 1e19.  The base is doped p-type with a concentration of 1e15,
and the collector is doped n-type with a concentration of 1e17.  The 
emitter and collector diffusions profiles are gaussian.  The doping, the
junctions and the grid is then plotted.

The file that solves for the current voltage characteristics is npn.p2.
The mesh file generated by npn1.p2 is imported in this file.  A contact
resistance is added to the base to be able to define a current going into
the base.  This is useful in solving for the I-V charcteristic, since its
better to define a base current then to put a "hard" voltage across the 
base emitter junction.

A newton two carrier solution method is used to account for both holes 
and electrons in the NPN device.  The models used Shockley-Read-Hall and
Auger recombination, concentration and field dependent mobilities, and
a temperature of 300 degree kelvin.  

The solve statements then solve for the base emitter voltage versus the 
collector current.  The collector is biased at 5 volts and the gate 
voltage is then ramped up.  A series of solve statements then solve for
the Ic versus Vce characteristics.  Here the base voltage is biased to a 
particular value and then the collector voltage is ramped down from 5
volts to 0.  The base bias is then increased and the collector is again
ramped down from 5 volts to 0.  The intermediate output files are saved
and bias steps are small in order to guarantee convergence.  The two IV 
characteristics are then plotted.
