Non-isothermal charge simulations

marc-flex · marc-flex · commit ddaaccbef13a · 2025-07-16T12:22:26.000+02:00
diff --git a/tests/test_components/test_heat_charge.py b/tests/test_components/test_heat_charge.py
@@ -1170,23 +1170,30 @@ def Si_p(self):
         semiconductor = CHARGE_SIMULATION.intrinsic_Si.charge
         semiconductor = semiconductor.updated_copy(
             N_a=CHARGE_SIMULATION.acceptors,
+        )
+        return CHARGE_SIMULATION.intrinsic_Si.updated_copy(
+            charge=semiconductor,
+            heat=td.SolidMedium(conductivity=1),
             name="Si_p",
         )
-        return CHARGE_SIMULATION.intrinsic_Si.updated_copy(charge=semiconductor)
 
     @pytest.fixture(scope="class")
     def Si_n(self):
         semiconductor = CHARGE_SIMULATION.intrinsic_Si.charge
         semiconductor = semiconductor.updated_copy(
             N_d=CHARGE_SIMULATION.donors,
+        )
+        return CHARGE_SIMULATION.intrinsic_Si.updated_copy(
+            charge=semiconductor,
+            heat=td.SolidMedium(conductivity=1),
             name="Si_n",
         )
-        return CHARGE_SIMULATION.intrinsic_Si.updated_copy(charge=semiconductor)
 
     @pytest.fixture(scope="class")
     def SiO2(self):
         return td.MultiPhysicsMedium(
             charge=td.ChargeInsulatorMedium(permittivity=3.9),
+            heat=td.SolidMedium(conductivity=2),
             name="SiO2",
         )
 
@@ -1267,18 +1274,13 @@ def capacitance_global_mnt(self):
     # Define charge settings as fixtures within the class
     @pytest.fixture(scope="class")
     def charge_tolerance(self):
-        return td.IsothermalSteadyChargeDCAnalysis(
-            temperature=300,
-            tolerance_settings=td.ChargeToleranceSpec(rel_tol=1e5, abs_tol=1e3, max_iters=400),
-            fermi_dirac=True,
-        )
-
-    @pytest.fixture(scope="class")
-    def charge_dc_regime(self):
-        return td.DCVoltageSource(voltage=[1])
+        return td.ChargeToleranceSpec(rel_tol=1e5, abs_tol=1e3, max_iters=400)
 
     def test_charge_simulation(
         self,
+        Si_n,
+        Si_p,
+        SiO2,
         oxide,
         p_side,
         n_side,
@@ -1288,9 +1290,14 @@ def test_charge_simulation(
         bc_n,
         bc_p,
         charge_tolerance,
-        charge_dc_regime,
     ):
         """Ensure charge simulation produces the correct errors when needed."""
+        # NOTE: start tests with isothermal spec
+        isothermal_spec = td.IsothermalSteadyChargeDCAnalysis(
+            temperature=300,
+            tolerance_settings=charge_tolerance,
+            fermi_dirac=True,
+        )
         sim = td.HeatChargeSimulation(
             structures=[oxide, p_side, n_side],
             medium=td.MultiPhysicsMedium(
@@ -1301,7 +1308,7 @@ def test_charge_simulation(
             size=CHARGE_SIMULATION.sim_size,
             grid_spec=td.UniformUnstructuredGrid(dl=0.05),
             boundary_spec=[bc_n, bc_p],
-            analysis_spec=charge_tolerance,
+            analysis_spec=isothermal_spec,
         )
 
         # At least one ChargeSimulationMonitor should be added
@@ -1336,6 +1343,45 @@ def test_charge_simulation(
             )
             _ = sim.updated_copy(boundary_spec=[new_bc_p, bc_n])
 
+        # test non isothermal spec
+        non_isothermal_spec = td.SteadyChargeDCAnalysis(tolerance_settings=charge_tolerance)
+
+        sim = sim.updated_copy(analysis_spec=non_isothermal_spec)
+        with pytest.raises(pd.ValidationError):
+            # remove heat from mediums
+            new_structs = []
+            for struct in sim.structures:
+                new_structs.append(
+                    struct.updated_copy(medium=struct.medium.updated_copy(heat=None))
+                )
+            _ = sim.updated_copy(structures=new_structs)
+
+        with pytest.raises(pd.ValidationError):
+            # remove charge from mediums
+            new_structs = []
+            for struct in sim.structures:
+                new_structs.append(
+                    struct.updated_copy(medium=struct.medium.updated_copy(charge=None))
+                )
+            _ = sim.updated_copy(structures=new_structs)
+
+        with pytest.raises(pd.ValidationError):
+            # make sure there is at least one semiconductor
+            new_structs = []
+            for struct in sim.structures:
+                if isinstance(struct.medium.charge, td.SemiconductorMedium):
+                    new_structs.append(
+                        struct.updated_copy(
+                            medium=struct.medium.updated_copy(
+                                charge=td.ChargeInsulatorMedium(permittivity=1),
+                                heat=None,
+                            )
+                        )
+                    )
+                else:
+                    new_structs.append(struct)
+            _ = sim.updated_copy(structures=new_structs)
+
     def test_doping_distributions(self):
         """Test doping distributions."""
         # Implementation needed
diff --git a/tidy3d/__init__.py b/tidy3d/__init__.py
@@ -20,6 +20,7 @@
 from tidy3d.components.spice.analysis.dc import (
     ChargeToleranceSpec,
     IsothermalSteadyChargeDCAnalysis,
+    SteadyChargeDCAnalysis,
 )
 from tidy3d.components.spice.sources.dc import DCCurrentSource, DCVoltageSource
 from tidy3d.components.spice.sources.types import VoltageSourceType
@@ -663,6 +664,7 @@ def set_logging_level(level: str) -> None:
     "Staircasing",
     "SteadyCapacitanceData",
     "SteadyCapacitanceMonitor",
+    "SteadyChargeDCAnalysis",
     "SteadyElectricFieldData",
     "SteadyElectricFieldMonitor",
     "SteadyEnergyBandData",
diff --git a/tidy3d/components/spice/analysis/dc.py b/tidy3d/components/spice/analysis/dc.py
@@ -49,19 +49,11 @@ class ChargeToleranceSpec(Tidy3dBaseModel):
     )
 
 
-class IsothermalSteadyChargeDCAnalysis(Tidy3dBaseModel):
+class SteadyChargeDCAnalysis(Tidy3dBaseModel):
     """
     Configures relevant steady-state DC simulation parameters for a charge simulation.
     """
 
-    temperature: pd.PositiveFloat = pd.Field(
-        300,
-        title="Temperature",
-        description="Lattice temperature. Assumed constant throughout the device. "
-        "Carriers are assumed to be at thermodynamic equilibrium with the lattice.",
-        units=KELVIN,
-    )
-
     tolerance_settings: ChargeToleranceSpec = pd.Field(
         default=ChargeToleranceSpec(), title="Tolerance settings"
     )
@@ -83,3 +75,17 @@ class IsothermalSteadyChargeDCAnalysis(Tidy3dBaseModel):
         "where very high doping may lead the pseudo-Fermi energy level to approach "
         "either the conduction or valence energy bands.",
     )
+
+
+class IsothermalSteadyChargeDCAnalysis(SteadyChargeDCAnalysis):
+    """
+    Configures relevant steady-state DC simulation parameters for a charge simulation.
+    """
+
+    temperature: pd.PositiveFloat = pd.Field(
+        300,
+        title="Temperature",
+        description="Lattice temperature. Assumed constant throughout the device. "
+        "Carriers are assumed to be at thermodynamic equilibrium with the lattice.",
+        units=KELVIN,
+    )
diff --git a/tidy3d/components/spice/types.py b/tidy3d/components/spice/types.py
@@ -2,6 +2,9 @@
 
 from typing import Union
 
-from tidy3d.components.spice.analysis.dc import IsothermalSteadyChargeDCAnalysis
+from tidy3d.components.spice.analysis.dc import (
+    IsothermalSteadyChargeDCAnalysis,
+    SteadyChargeDCAnalysis,
+)
 
-ElectricalAnalysisType = Union[IsothermalSteadyChargeDCAnalysis]
+ElectricalAnalysisType = Union[SteadyChargeDCAnalysis, IsothermalSteadyChargeDCAnalysis]
diff --git a/tidy3d/components/tcad/simulation/heat_charge.py b/tidy3d/components/tcad/simulation/heat_charge.py
@@ -35,7 +35,11 @@
 from tidy3d.components.medium import Medium
 from tidy3d.components.scene import Scene
 from tidy3d.components.spice.sources.dc import DCVoltageSource
-from tidy3d.components.spice.types import ElectricalAnalysisType
+from tidy3d.components.spice.types import (
+    ElectricalAnalysisType,
+    IsothermalSteadyChargeDCAnalysis,
+    SteadyChargeDCAnalysis,
+)
 from tidy3d.components.structure import Structure
 from tidy3d.components.tcad.analysis.heat_simulation_type import UnsteadyHeatAnalysis
 from tidy3d.components.tcad.boundary.specification import (
@@ -951,6 +955,44 @@ def check_transient_heat(cls, values):
                 )
         return values
 
+    @pd.root_validator(skip_on_failure=True)
+    def check_non_isothermal_is_possible(cls, values):
+        """Make sure that when a non-isothermal case is defined the structrures
+        have both electrical and thermal properties."""
+
+        analysis_spec = values.get("analysis_spec")
+        if isinstance(analysis_spec, SteadyChargeDCAnalysis) and not isinstance(
+            analysis_spec, IsothermalSteadyChargeDCAnalysis
+        ):
+            has_heat = False
+            has_elec = False
+            structures = values.get("structures")
+            for struct in structures:
+                if isinstance(struct.medium, MultiPhysicsMedium):
+                    if struct.medium.heat is not None:
+                        if isinstance(struct.medium.heat, SolidMedium):
+                            has_heat = True
+                    if struct.medium.charge is not None:
+                        if isinstance(struct.medium.charge, SemiconductorMedium):
+                            has_elec = True
+
+            if not has_heat and has_elec:
+                raise SetupError(
+                    "The current simulation is defined as non-isothermal but no solid "
+                    "materials with heat properties have been defined. "
+                )
+            elif not has_elec and has_heat:
+                raise SetupError(
+                    "The current simulation is defined as non-isothermal but no "
+                    "semiconductor materials have been defined. "
+                )
+            elif not has_heat and not has_elec:
+                raise SetupError(
+                    "The current simulation is defined as non-isothermal but no "
+                    "solid or semiconductor materials have been defined. "
+                )
+        return values
+
     @equal_aspect
     @add_ax_if_none
     def plot_property(
@@ -1735,7 +1777,8 @@ def _get_simulation_types(self) -> list[TCADAnalysisTypes]:
 
         # NOTE: for the time being, if a simulation has SemiconductorMedium
         # then we consider it of being a 'TCADAnalysisTypes.CHARGE'
-        if isinstance(self.analysis_spec, ElectricalAnalysisType):
+        ChargeTypes = (SteadyChargeDCAnalysis, IsothermalSteadyChargeDCAnalysis)
+        if isinstance(self.analysis_spec, ChargeTypes):
             if self._check_if_semiconductor_present(self.structures):
                 return [TCADAnalysisTypes.CHARGE]
 
