public void Evaluate()
{
var phiS = SurfacePotential;
var storePotential = EvalPoints[0].Potential;
// First remove all the points
EvalPoints.Clear();
// Find the thickness through integration
// Integrate from 0 to the surface potential
// Integrate 2000 times so change stepSize depending on the surface potential
var stepSize = phiS / 20;
stepSize = phiS > ElectricPotential.Zero ?
ElectricPotential.Abs(stepSize) : -ElectricPotential.Abs(stepSize);
var previousValue = 1 / GetElectricField(phiS).VoltsPerMeter;
var runningThickness = Length.Zero;
var previousThickness = Length.Zero;
var point = new EvalPoint
{
Location = runningThickness,
ChargeDensity = GetChargeY(phiS),
ElectricField = new ElectricField(1 / previousValue),
Potential = phiS
};
EvalPoints.Add(point);
for (var i = 1; ElectricPotential.Abs(phiS - stepSize * i)
> ElectricPotential.FromMillivolts(1) && i < 10000; i++)
{
var potentialValue = phiS - stepSize * i;
var value = 1 / GetElectricField(potentialValue).VoltsPerMeter;
previousThickness = runningThickness;
runningThickness += new Length(((previousValue + value) / 2) * stepSize.Volts);
if (double.IsNaN(runningThickness.Meters))
{
Debug.WriteLine("Por que Nan??");
}
point = new EvalPoint
{
Location = runningThickness,
ChargeDensity = GetChargeY(potentialValue) * 1E-8,
ElectricField = new ElectricField(1 / value),
Potential = potentialValue
};
EvalPoints.Add(point);
previousValue = value;
}
// Now add the offset in potential
var checkCharge = ChargeDensity.Zero; // check and see if the charges add up
foreach (var checkPoint in EvalPoints)
{
checkPoint.Potential = checkPoint.Potential + storePotential;
checkPoint.Potential = checkPoint.Potential - phiS;
checkCharge += checkPoint.ChargeDensity;
}
}
private void Evaluate(CancellationToken cancellationToken = default(CancellationToken))
{
// Don't do anything if the structure isn't valid
if (!IsValid)
{
return;
}
int iterationNumber;
// Since we integrate left to right, we want to specify the voltage on the left
var voltageBias = -Bias + WorkFunctionDifference;
// Iterate until we find the desired voltage
var chargeHigh = ChargeDensity.FromCoulombsPerSquareCentimeter(1.0);
var chargeLow = ChargeDensity.FromCoulombsPerSquareCentimeter(-1.0);
var chargeGuess = (chargeHigh + chargeLow) / 2;
// !!!!!!!!!!!!!!!!!!
EvaluateGivenCharge(chargeGuess, cancellationToken);
// !!!!!!!!!!!!!!!!!!
if (cancellationToken.IsCancellationRequested)
{
return;
}
var potentialCalc = BottomLayer.EvalPoints[1].Potential;
var tinyPositiveBias = new ElectricPotential(1e-6);
var tinyNegativeBias = new ElectricPotential(-1e-6);
// Iterate
for (iterationNumber = 0;
(potentialCalc > voltageBias + ElectricPotential.Abs(voltageBias * 1e-6)
+ tinyPositiveBias ||
potentialCalc < voltageBias - ElectricPotential.Abs(voltageBias * 1e-6)
+ tinyNegativeBias) &&
iterationNumber < maximumIterations;
iterationNumber++)
{
if (cancellationToken.IsCancellationRequested)
{
return;
}
if (potentialCalc > voltageBias)
{
chargeLow = chargeGuess;
}
else
{
chargeHigh = chargeGuess;
}
// Update the guessCharge
chargeGuess = (chargeHigh + chargeLow) / 2;
// !!!!!!!!!!!!!!!!!!
EvaluateGivenCharge(chargeGuess, cancellationToken);
// !!!!!!!!!!!!!!!!!!
if (cancellationToken.IsCancellationRequested)
{
return;
}
potentialCalc = BottomLayer.EvalPoints[1].Potential;
if (iterationNumber == maximumIterations - 1)
{
if (!(potentialCalc > voltageBias + ElectricPotential.FromMillivolts(1) ||
potentialCalc < voltageBias - ElectricPotential.FromMillivolts(1)))
{
// TODO: Inform that solution only found to accuracy of 1e-3
}
else
{
NoSolution = true;
return;
}
}
}
// If the last material is a semiconductor, fill in the missing points
if (IsBottomLayerSemiconductor)
{
((Semiconductor)BottomLayer).Evaluate();
// Now subtract the potential from all the points so the right is ref to 0
var lastPoint = BottomLayer.EvalPoints.Last();
var potential = lastPoint.Potential;
foreach (var layer in Layers)
{
foreach (var ep in layer.EvalPoints)
{
if (cancellationToken.IsCancellationRequested)
{
return;
}
ep.Potential = ep.Potential - potential;
}
}
var trueLast = lastPoint.DeepClone();
if (trueLast.Location < Length.FromNanometers(50))
{
trueLast.Location = Length.FromNanometers(50);
}
BottomLayer.EvalPoints.Add(trueLast);
}
NoSolution = false;
/*
* Debug.WriteLine(String.Format("Evaluation finished after {0} iterations in {1} ms",
* iterationNumber, stopwatch.ElapsedMilliseconds));
*/
}