public double Get_Surface_Charge(Band_Data chem_pot, ILayer[] layers)
{
// calculate the electric field just below the surface
int surface = (int)(-1.0 * Math.Floor(Geom_Tool.Get_Zmin(layers) / exp.Dz_Pot));
double eps = Geom_Tool.Find_Layer_Below_Surface(layers).Permitivity;
// by Gauss' theorem, rho = - epsilon_0 * epsilon_r * dV/dz
double surface_charge = -1.0 * eps * (chem_pot[surface - 1] - chem_pot[surface - 2]) / exp.Dz_Pot;
// divide by - q_e to convert the chemical potential into a potential
surface_charge /= -1.0 * Physics_Base.q_e;
return(surface_charge);
}
/// <summary>
/// initiates the poisson solver by writing the input file for the parameter handlers of the initcalc and newton methods
/// </summary>
public override void Initiate_Poisson_Solver(Dictionary <string, double> device_dimensions, Dictionary <string, double> boundary_conditions)
{
// get split gate specific device dimensions
device_dimensions["zmin_pot"] = exp.Layers[1].Zmin;
device_dimensions["pmma_depth"] = exp.Layers[exp.Layers.Length - 1].Zmax;
device_dimensions["cap_depth"] = Geom_Tool.Find_Layer_Below_Surface(exp.Layers).Zmin;
device_dimensions["interface_depth"] = exp.Layers[1].Zmax;
device_dimensions["buffer_depth"] = exp.Layers[2].Zmax;
// write the parameter details for the initial potential calculation
StreamWriter sw_initcalc = new StreamWriter(initcalc_parameterfile);
// check if the top layer is air... if so, we need to use natural boundary conditions on the upper surface
bool natural_top_bc = (exp.Layers[exp.Layers.Length - 1].Material == Material.Air);
if (natural_top_bc)
{
device_dimensions["top_V"] = 0.0;
}
sw_initcalc.WriteLine("subsection System Geometry");
sw_initcalc.WriteLine("\tset zmin_pot = " + device_dimensions["zmin_pot"].ToString());
sw_initcalc.WriteLine("\tset split_width = " + device_dimensions["split_width"].ToString());
sw_initcalc.WriteLine("\tset pmma_depth = " + device_dimensions["pmma_depth"].ToString());
sw_initcalc.WriteLine("\tset cap_depth = " + device_dimensions["cap_depth"].ToString());
sw_initcalc.WriteLine("\tset interface_depth = " + device_dimensions["interface_depth"].ToString());
sw_initcalc.WriteLine("\tset buffer_depth = " + device_dimensions["buffer_depth"].ToString());
sw_initcalc.WriteLine("end");
sw_initcalc.WriteLine("subsection Boundary Conditions");
sw_initcalc.WriteLine("\tset top_bc = " + (boundary_conditions["top_V"] * Physics_Base.energy_V_to_meVpzC).ToString());
sw_initcalc.WriteLine("\tset bottom_bc = " + (boundary_conditions["bottom_V"] * Physics_Base.energy_V_to_meVpzC).ToString());
sw_initcalc.WriteLine("\tset split_bc1 = " + (boundary_conditions["V0"] * Physics_Base.energy_V_to_meVpzC).ToString());
sw_initcalc.WriteLine("\tset split_bc2 = " + (boundary_conditions["V1"] * Physics_Base.energy_V_to_meVpzC).ToString());
sw_initcalc.WriteLine("\tset surface_bc = " + (0.5 * boundary_conditions["surface"]).ToString()); // note that the surface "kink" is halved...
// not sure why, but this is deal.II specific
sw_initcalc.WriteLine("end");
sw_initcalc.WriteLine("subsection Carrier Density Parameters");
sw_initcalc.WriteLine("\tset ny_dens = " + exp.Ny_Dens.ToString());
sw_initcalc.WriteLine("\tset nz_dens = " + exp.Nz_Dens.ToString());
sw_initcalc.WriteLine("\tset ymin_dens = " + exp.Ymin_Dens.ToString());
sw_initcalc.WriteLine("\tset ymax_dens = " + (exp.Ymin_Dens + exp.Dy_Dens * (exp.Ny_Dens - 1)).ToString());
sw_initcalc.WriteLine("\tset zmin_dens = " + exp.Zmin_Dens.ToString());
sw_initcalc.WriteLine("\tset zmax_dens = " + (exp.Zmin_Dens + exp.Dz_Dens * (exp.Nz_Dens - 1)).ToString());
sw_initcalc.WriteLine("end");
sw_initcalc.WriteLine("subsection Donor Density Parameters");
sw_initcalc.WriteLine("\tset nz_donor = " + nz_donor);
sw_initcalc.WriteLine("\tset zmin_donor = " + zmin_donor);
sw_initcalc.WriteLine("\tset zmax_donor = " + zmax_donor);
sw_initcalc.WriteLine("end");
sw_initcalc.WriteLine("set natural top_bc = " + natural_top_bc.ToString().ToLower());
sw_initcalc.Close();
// and write the parameter details needed for the newton step
StreamWriter sw_newton = new StreamWriter(newton_parameterfile);
sw_newton.WriteLine("subsection System Geometry");
sw_newton.WriteLine("\tset zmin_pot = " + device_dimensions["zmin_pot"].ToString());
sw_newton.WriteLine("\tset split_width = " + device_dimensions["split_width"].ToString());
sw_newton.WriteLine("\tset pmma_depth = " + device_dimensions["pmma_depth"].ToString());
sw_newton.WriteLine("\tset cap_depth = " + device_dimensions["cap_depth"].ToString());
sw_newton.WriteLine("\tset interface_depth = " + device_dimensions["interface_depth"].ToString());
sw_newton.WriteLine("\tset buffer_depth = " + device_dimensions["buffer_depth"].ToString());
sw_newton.WriteLine("end");
sw_newton.WriteLine("subsection Carrier Density Parameters");
sw_newton.WriteLine("\tset ny_dens = " + exp.Ny_Dens.ToString());
sw_newton.WriteLine("\tset nz_dens = " + exp.Nz_Dens.ToString());
sw_newton.WriteLine("\tset ymin_dens = " + exp.Ymin_Dens.ToString());
sw_newton.WriteLine("\tset ymax_dens = " + (exp.Ymin_Dens + exp.Dy_Dens * (exp.Ny_Dens - 1)).ToString());
sw_newton.WriteLine("\tset zmin_dens = " + exp.Zmin_Dens.ToString());
sw_newton.WriteLine("\tset zmax_dens = " + (exp.Zmin_Dens + exp.Dz_Dens * (exp.Nz_Dens - 1)).ToString());
sw_newton.WriteLine("end");
sw_newton.WriteLine("set natural top_bc = " + natural_top_bc.ToString().ToLower());
sw_newton.Close();
}
public override void Initialise(Dictionary <string, object> input_dict)
{
// simulation domain inputs
Get_From_Dictionary <double>(input_dict, "dz", ref dz_dens); dz_pot = dz_dens;
Get_From_Dictionary(input_dict, "nz", ref nz_dens); nz_pot = nz_dens;
// physics parameters are done by the base method
base.Initialise(input_dict);
Get_From_Dictionary <bool>(input_dict, "illuminated", ref illuminated, true);
// check that the size of the domain [(nz_pot-1) * dz_pot] is not larger than the band structure
if (layers[layers.Length - 1].Zmax - Geom_Tool.Get_Zmin(layers) < (Nz_Pot - 1) * Dz_Pot)
{
throw new Exception("Error - the band structure provided is smaller than the simulation domain!\nUse nz = " + (int)Math.Ceiling((layers[layers.Length - 1].Zmax - Geom_Tool.Get_Zmin(layers)) / Dz_Pot) + " instead");
}
// and check that the top of the domain is the surface (unless this check is overloaded)
bool surface_override = false; Get_From_Dictionary <bool>(input_dict, "surface_check", ref surface_override, true);
if (!surface_override && Geom_Tool.Find_Layer_Below_Surface(layers).Zmax - Geom_Tool.Get_Zmin(layers) - Nz_Pot * Dz_Pot != 0.0)
{
throw new Exception("Error - the top of the domain is not the surface!\nUse the input \"surface_check\" to override");
}
// calculate the top and bottom of the domain
input_dict["zmin"] = Geom_Tool.Get_Zmin(layers);
input_dict["zmax"] = Geom_Tool.Get_Zmin(layers) + dz_pot * nz_pot;
// and split gate dimensions
device_dimensions.Add("bottom_position", (double)input_dict["zmin"]);
device_dimensions.Add("top_position", (double)input_dict["zmax"]);
// check whether the bottom should be fixed
if (input_dict.ContainsKey("bottom_V"))
{
fix_bottom_V = true;
}
// initialise the dictionary which contains the surface charges at each temperature
surface_charge = new Dictionary <double, double>();
// double check whether you want to use FlexPDE
if (input_dict.ContainsKey("use_FlexPDE"))
{
using_flexPDE = (bool)input_dict["use_FlexPDE"];
}
// Initialise potential solver
pois_solv = new OneD_PoissonSolver(this, using_flexPDE, input_dict);
Initialise_DataClasses(input_dict);
// if the input dictionary already has the dopent distribution, we don't need to recalculate it
if (input_dict.ContainsKey("Dopent_Density"))
{
dopents_calculated = true;
}
// Get carrier type for DFT calculations (default is electron)
if (input_dict.ContainsKey("carrier_type"))
{
carrier_type = (Carrier)Enum.Parse(typeof(Carrier), (string)input_dict["carrier_type"]);
}
Console.WriteLine("Experimental parameters initialised");
}
private void Draw_Domain(StreamWriter sw)
{
sw.WriteLine("EXTRUSION");
sw.WriteLine("\tSURFACE \"Substrate\"\tz = " + exp.Layers[0].Zmax.ToString() + " * z_scaling");
for (int i = 1; i < exp.Layers.Length; i++)
{
sw.WriteLine("\t\tLAYER \"" + i.ToString() + "\"");
sw.WriteLine("\tSURFACE \"" + i.ToString() + "\"\tz = " + exp.Layers[i].Zmax.ToString() + " * z_scaling");
}
sw.WriteLine();
sw.WriteLine("BOUNDARIES");
sw.WriteLine("\tSURFACE \"Substrate\" VALUE(u) = bottom_bc");
sw.WriteLine("\tSURFACE \"" + (Geom_Tool.Find_Layer_Below_Surface(exp.Layers).Layer_No - 1).ToString() + "\" NATURAL(u) = surface_bc");
//sw.WriteLine("\tSURFACE \"" + (exp.Layers.Length - 1).ToString() + "\" NATURAL(u) = 0");
sw.WriteLine("\tSURFACE \"" + (exp.Layers.Length - 1).ToString() + "\" VALUE(u) = top_bc");
sw.WriteLine();
sw.WriteLine("\tREGION 1");
for (int i = 1; i < exp.Layers.Length; i++)
{
sw.WriteLine("\t\tLAYER \"" + i.ToString() + "\"");
sw.WriteLine("\t\teps = " + exp.Layers[i].Permitivity.ToString());
sw.WriteLine("\t\tband_gap = " + exp.Layers[i].Band_Gap.ToString());
sw.WriteLine();
}
sw.WriteLine("\t\tSTART(-lx / 2, -ly / 2 * y_scaling)");
sw.WriteLine("\t\tLINE TO (-lx / 2, ly / 2 * y_scaling)");
sw.WriteLine("\t\tLINE TO (lx / 2, ly / 2 * y_scaling)");
sw.WriteLine("\t\tLINE TO (lx / 2, -ly / 2 * y_scaling)");
sw.WriteLine("\t\tLINE TO CLOSE");
sw.WriteLine();
int count = 2;
int voltage_count = 0;
for (int i = 0; i < exp.Layers.Length; i++)
{
if (exp.Layers[i].No_Components > 1)
{
for (int j = 1; j < exp.Layers[i].No_Components; j++)
{
ILayer current_layer = exp.Layers[i].Get_Component(j);
if (current_layer.Geometry == Geometry_Type.triangle_slab)
{
throw new NotImplementedException("Triangles are not currently implemented... Sorry");
}
string xmin = "-1.0 * split_length / 2";
string xmax = "split_length / 2";
string ymin = "-ly / 2";
string ymax = "ly / 2";
if (current_layer.Xmin != double.MinValue)
{
xmin = current_layer.Xmin.ToString();
}
if (current_layer.Xmax != double.MaxValue)
{
xmax = current_layer.Xmax.ToString();
}
if (current_layer.Ymin != double.MinValue)
{
ymin = current_layer.Ymin.ToString();
}
if (current_layer.Ymax != double.MaxValue)
{
ymax = current_layer.Ymax.ToString();
}
sw.WriteLine("\tLIMITED REGION " + count.ToString());
sw.WriteLine("\t\tSURFACE \"" + (i - 1).ToString() + "\" VALUE(u) = V" + voltage_count.ToString());
sw.WriteLine("\t\tSURFACE \"" + i.ToString() + "\" VALUE(u) = V" + voltage_count.ToString());
sw.WriteLine("\t\tLAYER \"" + i.ToString() + "\" VOID");
sw.WriteLine("\t\tSTART (" + xmin + ", " + ymax + " * y_scaling)");
sw.WriteLine("\t\tLAYER \"" + i.ToString() + "\"");
sw.WriteLine("\t\tVALUE(u) = V" + voltage_count.ToString());
sw.WriteLine("\t\tmesh_spacing = 100");
sw.WriteLine("\t\tLINE TO (" + xmax + ", " + ymax + " * y_scaling)");
sw.WriteLine("\t\tLINE TO (" + xmax + ", " + ymin + " * y_scaling) TO (" + xmin + ", " + ymin + " * y_scaling) TO CLOSE");
sw.WriteLine();
count++;
voltage_count++;
}
}
}
if (voltage_count != gate_bcs.Count)
{
sw.Close();
throw new Exception("Error - not enough voltages for the number of gates... see FlexPDE file...");
}
}