1. 2D_Vpit LED_Build a structure (material region setting)
2. 2D_Vpit LED_Mesh setting
3. 2D_Vpit LED_Set up the material parameters
4. 2D_Vpit LED_Additional functions
5. 2D_Vpit LED_Bias setting
6. 2D_Vpit LED_Run the simulation
7. 2D_Vpit LED_View the results
