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1D DDCC

1D DDCC is named from one dimensional Drift-diffusion Charge Control solver. This solver initially solved Poisson Schrodinger Equation developed in U of M, Ann Arbor. Then the function of drift-diffusional solver was added by Prof. Yuh-Renn Wu when he was PhD student in UM and got its name DDCC. After Prof. Wu was an professor in NTU, he continues to improvement of this program. This solver now can solve many different problems such as trap problem, Gaussian shape tail state models, field dependent mobility, optical cavity mode model, and the newly added localization landscape model. The Polarization charges induced in nitride system can be considered as well. The nitride based 6 band k.p solver was also added into this program so that it can analyze the band structure variation due to strain. This code is written with Fortran language.

1D-DDCC includes following functions:
1. tunnable parameters for all basic material properties
2. heterojunction simulation
3. dopant activation energy
4. eigen solver for schrodinger equation.
5. k.p solver of qw for wurtzite structures.
6. traps model single level traps gaussian distribution traps.
7. tail state dos state models gausian distribution of tail states expenetional decay model etc.
8. tunneling probability calculation
9. including the effect of polarization charge at the interface
10. impact ionization model is included.
11. btbt model in included.
12. landscape model and self-consistent poisson drift-diffusion equation landscape model
13. exciton diffusion nonradiative recombination quenching for organic materials is included.
14. field dependent mobility model is included 1 pool frankel mode 2 field dependent mobility model
15. radiative srh auger recombination model is included.
16. light generation simple solar spectrum absorption with alpha is included for solar cell modeling.

2D DDCC

2D DDCC is named from two dimensional Drift-diffusion Charge Control solver. This is 2D finite element based Poisson and drift-diffusion solver developed by Dr. Yuh-Renn Wu. This solver initially developed with the thermal solver. Then the Poisson and drift-diffusion solver was added into this project. This solver was initially developed to solves AlGaN/GaN HEMT structure. Therefore, the 1D Schrodinger cross section solver was added into the program for obtaining the confined state information. The electric field distribution was then used in Monte Carlo program for high field transport. After Dr. Wu returned NTU, the program was then modified to solve LED based current spreading problem. The mesh algorithm was then improve gradually in order to deal with certain problem. After years development, the 2D FEM based Schrodinger eigen solver was added. It also accept additional module to read in the optical field from 2D FD-TD program so that it can consider the solar cell problem. Then the 2D ray tracing program was added into this project to solve the light extraction problem. This solver now can solve many different problems such as trap problem, Gaussian shape tail state models, field dependent mobility, thermal, light extraction. Recently, localization landscape model was also added into this program so that it can calculate the effective quantum potential very efficiently. This code is written with Fortran language.

This solver can solve the 2D FEM based Poisson drift-diffusion equation self-consistently and solve Schrodinger equation after poison and drift-diffusion solver is converged due to time issues. it has a built-in mesh generator. It also includes following functions:

1. tunnable parameters for all basic material properties
2. heterojunction simulation
3. dopant activation energy
4. eigen solver for schrodinger equation.
5. traps model single level traps gaussian distribution traps.
6. tail state dos state models gausian distribution of tail states expenetional decay model etc.
7. including the effect of polarization charge at the interface
8. impact ionization model is included.
9. BTBT model in included.
10. landscape model and self-consistent Poisson drift-diffusion equation landscape model
11. exciton diffusion nonradiative recombination quenching for organic materials is included.
12. field dependent mobility model is included 1 pool frankel mode 2 field dependent mobility model
13. Radiative, SRH, Auger recombination models are included.
14. light generation simple solar spectrum absorption with alpha is included for solar cell modeling. it can also read in generation profile from optical solver such as 2D FD-TD
15. Monte Carlo ray tracing program for light extraction.

3D DDCC

3D DDCC is named from three dimensional Drift-diffusion Charge Control solver. This is 3D finite element based Poisson and drift-diffusion solver developed by Dr. Yuh-Renn Wu. This solver initially developed with the 3D FEM thermal solver by Dr. Chi-kang Li when he was PhD student in Dr. Wu's group. Then the Poisson and drift-diffusion solver was added by Dr. Wu into this project. This solver was basically an expansion of 2D program into 3D program. Therefore, all new algorithm added in 2D program will be soon added into 3D program if no errors was found. The mesh algorithm was from Gmsh program. It also accept other mesh algorithm as long as it can be converged into gmsh format. The 3D FEM based Schrodinger eigen solver was also added. It also accept additional module to read in the optical field from 3D FD-TD program so that it can consider the solar cell problem. Then the 3D ray tracing program was developing. This solver now can solve many different problems such as trap problem, Gaussian shape tail state models, field dependent mobility, thermal, light extraction. Recently, 3D localization landscape model was also added into this program so that it can calculate the effective quantum potential very efficiently. This code is written with Fortran language.

It includes following functions :

1. tunnable parameters for all basic material properties
2. heterojunction simulation
3. dopant activation energy
4. eigen solver for schrodinger equation.
5. traps model single level traps gaussian distribution traps.
6. tail state dos state models gausian distribution of tail states expenetional decay model etc.
7. including the effect of polarization charge at the interface
8. impact ionization model is included.
9. BTBT model in included.
10. landscape model and self-consistent poisson drift-diffusion equation landscape model
11. exciton diffusion nonradiative recombination quenching for organic materials is included.
12. field dependent mobility model is included 1 pool frankel mode 2 field dependent mobility model
13. radiative, SRH, Auger recombination models are included.
14. light generation simple solar spectrum absorption with alpha is included for solar cell modeling. it can also read in generation profile from optical solver such as 3d FD-TD.

Matlab based GUI interface

The 1D to 3D DDCC solver was command line based. It can easily used in cluster system with large amount of job submission. However, it is not easy for general user to use. In 2010, a needed for GUI interface is increasing due to some industrial collaboration project. In 2011, Prof. Wu was visiting UCSB as a visiting scholar without teaching loading. He spent 5 month to develop 1D to 3D GUI interface with Matlab GUI function. The Matlab's GUI function is based on JAVA so that it can be used in both linux, windows, and even MAC OS system. This program is growing with new functions added into DDCC solver. So the interface input arrangment is not as ideal as logic but based on time of development. After years continuing improvement, now it might be much easier to use. However, due to licensing issues from from Matlab, the GUI program is now going to to be transferring into other language based environment. The source code of this GUI program is opened and was put in the GUI release. The GUI program is simply assist user to generate input file for DDCC to read. Therefore, ideally that DDCC user can do the simulation without this GUI program. However, it would be good for new user to use GUI interface to avoid some setting problems.

ITRI-NTU 3D-FDTD

3D-FDTD is named from three dimensional finite difference time domain method. This program models computational electrodynamics which is refer to the book Computational Electrodynamics: The Finite-Difference Time-Domain Method, Third Edition, by Allen Taflove. [1]