SiLENSe—software tool for light emitting diode (LED) bandgap engineering

SiLENSe is software tool for 1D simulation of the active region of light-emitting diodes (LEDs) and laser diodes (LDs) made of cubic III-V compounds (AlGaInAs, AlGaInP, InGaAsP, AlGaInSb, and GaInAsSb) and wurtzite III-nitrides (AlInGaN and ZnMgO). It can be used by both device and epitaxy engineers. Carrier transport model implemented in the software allows simulation of polar, semipolar, and nonpolar structures and accounts for specific features of nitride heterostructures including polarization effects, high density of threading dislocations and Auger recombination. The last one is responsible for the droop of internal quantum efficiency observed in nitride LEDs at moderate and high current densities. SiLENSe provides distribution of critical parameters over the LED heterostructure, including partial (electron and hole) currents, electric field and potential, rate of carrier recombination, and carrier concentrations. The program is capable of calculations for graded-composition heterostructures.

Note that one more channel of non-radiative recombination – the surface recombination at the sidewalls of the LED mesa – is simulated at the chip level, see micro-LEDs.

SiLENSe provides the following characteristics of an LED heterostructure:

  • Band diagram of an LED at various biases;
  • Distribution of electron and hole concentrations in the device structure;
  • Electric field distribution;
  • Radiative and non-radiative recombination rates;
  • Dependence of the current density on the p-n junction bias (I-V curve);
  • Internal quantum efficiency (IQE) dependence on the current density;
  • Wave functions of electrons and holes in quantum wells;
  • Emission and gain spectra of individual quantum wells and the whole structure;
  • Waveguide modes (TE and TM) of an edge-emitting laser diode*;
  • Threshold current and power-current characteristic of an edge-emitting laser diode*.

* these options are available in Laser Edition only

The above information forms a good basis for the LED structure optimization and for development of new light emitting devices.

Supported materials

SiLENSe software includes a special module for easy specification of materials properties. The default database contains properties of cubic III-V (AlGaInAs, AlGaInP, InGaAsP, AlGaInSb, and GaInAsSb)  and wurtzite (AlInGaN and ZnMgO) materials. The user can edit the existing materials  add new materials. 

Examples of simulations

To illustrate SiLENSe capabilities we suggest for your attention the following simulation examples:

Example 1 Blue SQW and MQW LED heterostructures

Example 2 Hybrid II-O/III-N LED (ZnO-based LED)

Example 3 Polar/Semipolar/Nonpolar Heterostructures


Some of these example are accompanied by project files that allow the SiLENSe users to reproduce the computations.

Band diagram of an MQW LED

Band diagram of an MQW LED


The SiLENSe software has a friendly graphical user interface (GUI) designed to minimize user efforts needed to start simulations. Interactive visualization of the calculation results provides an excellent representation of the LED operation. The results can be also exported for visualization in external viewers.

Layer-by-layer LED structure specification and input data visualization.

Layer-by-layer visualization of the input date specification for an LED structure

Band diagram and carrier wave functions

Band diagram and carrier wave functions

Publications by STR team and SiLENSe users

GaN-based devices

“Dislocation and indium droplet related emission inhomogeneities in InGaN LEDs” by  Len van DeurzenMikel Gómez RuizKevin LeeHenryk TurskiShyam BharadwajRyan PageVladimir ProtasenkoHuili (Grace) XingJonas Lähnemann, and Debdeep Jena, 2021 J. Phys. D: Appl. Phys. 54 495106,

“Polarization-dependent hole generation in 222 nm-band AlGaN-based Far-UVC LED: a way forward to the epi-growers of MBE and MOCVD”, Shahzeb Malik, Muhammad Usman, M. Ajmal Khan, and Hideki Hirayamab, J. Mater. Chem. 2021,

“Comparison of Ultraviolet B Light-Emitting Diodes with Single or Triple Quantum Wells”, Tim Kolbe,* Arne Knauer, Jan Ruschel, Jens Rass, Hyun Kyong Cho, Sylvia Hagedorn, Johannes Glaab, Neysha Lobo Ploch, Sven Einfeldt, and Markus Weyers, PSS 2021,

“Light-emitting diodes with AlN polarization-induced buried tunnel junctions: A second look” by Kevin LeeShyam BharadwajYu-Tsun ShaoLen van DeurzenVladimir ProtasenkoDavid A. Muller, Huili Grace Xing, and Debdeep Jena, Appl. Phys. Lett. 117, 061104 (2020),

“Enhanced injection efficiency and light output in bottom tunnel-junction light-emitting diodes”, Shyam Bharadwaj, Jeffrey Miller, Kevin Lee, Joshua Lederman, Marcin Siekacz, Huili (Grace) Xing, Debdeep Jena, Czesław Skierbiszewski, and Henryk Turski, Optics Express, Vol. 28, Issue 4, pp. 4489-4500 (2020),

“Monolithically integrated white light LEDs on (11–22) semi-polar GaN templates”, N. Poyiatzis, M. Athanasiou, J. Bai, Y. Gong & T. Wang, Scientific Reports, (2019) 9:1383,

“Effect of Carrier Localization on Recombination Processes and Efficiency of InGaN-Based LEDs Operating in the “Green Gap” ” by Sergey Yu. Karpov,  Appl. Sci. 2018, 8(5), 818;

“Flexible deep-ultraviolet light-emitting diodes for significant improvement of quantum efficiencies by external bending”, Shahab Shervin, Seung Kyu Oh, Hyun Jung Park, Keon-Hwa Lee, Mojtaba Asadirad, Seung-Hwan Kim, Jeomoh Kim, Sara Pouladi, Sung-Nam Lee, Xiaohang Li, Joon Seop Kwak, and Jae-Hyun Ryou, J. Phys. D: Appl. Phys. 51 (2018) 105105 (7pp),

“Improved carrier injection of AlGaN-based deep ultraviolet light emitting diodes with graded superlattice electron blocking layers”, Byeongchan So, Jinwan Kim, Taemyung Kwak, Taeyoung Kim, Joohyoung Lee, Uiho Choi and Okhyun Nam, RSC Adv., 2018, 8, 35528, DOI: 10.1039/c8ra06982d

“Deep Ultraviolet Light Emitters Based on (Al,Ga)N/GaN Semiconductor Heterostructures”, PhD thesis by Yu-Han Liang,  Carnegie Mellon University, 2017

“Carrier localization in InGaN by composition fluctuations: implication to the “green gap” ” by Sergey Yu. Karpov, Photonics Research Vol. 5, No. 2, pp. A7-A12 (2017),

“Efficiency of True-Green Light Emitting Diodes: Non-Uniformity and Temperature Effects” by Ilya E. Titkov, Sergey Yu. Karpov, Amit Yadav, Denis Mamedov, Vera L. Zerova, and Edik Rafailov, Materials 2017, 10(11), 1323,

“Bendable III‑N Visible Light-Emitting Diodes beyond Mechanical Flexibility: Theoretical Study on Quantum Efficiency Improvement and Color Tunability by External Strain” by Shahab Shervin,  Seung-Hwan Kim, Mojtaba Asadirad, S. Yu. Karpov, Daria Zimina, and Jae-Hyun Ryou, ACS Photonics 2016, 3, 3, 486–493,

“Determination of recombination coefficients in InGaN quantum-well light-emitting diodes by small-signal time-resolved photoluminescence” by Felix Nippert, Sergey Karpov, Ines Pietzonka, Bastian Galler, Alexander Wilm, Thomas Kure, Christian Nenstiel, Gordon Callsen, Martin Strassburg, Hans-Jürgen Lugauer, and Axel Hoffmann, 2016 Jpn. J. Appl. Phys. 55 05FJ01

“Multi-color monolithic III-nitride light-emitting diodes: Factors controlling emission spectra and efficiency” by S.Yu. Karpov, N.A. Cherkashin, W.V. Lundin, A.E. Nikolaev, A.V. Sakharov, M.A. Sinitsin, S.O. Usov, E. E. Zavarin, and A. F. Tsatsulnikov, Phys. Status Solidi A 213, No. 1, 19–29 (2016) / DOI 10.1002/pssa.201532491

“Light-emitting diodes for solid-state lighting: searching room for improvements” by Sergey Yu. Karpov, Proc. SPIE 9768, Light-Emitting Diodes: Materials, Devices, and Applications for Solid State Lighting XX, 97680C (8 March 2016);

“Spectral dependence of light extraction efficiency of high-power III-nitride light-emitting diodes” by Sergey Yu. Karpov, Michael Binder, Bastian Galler, and Dario Schiavon, Phys. Status Solidi RRL 9, No. 5, 312–316 (2015) / DOI 10.1002/pssr.201510073

“Effect of the design of the active region of monolithic multi-color LED heterostructures on their spectra and emission efficiency” by A. F. Tsatsulnikov, W. V. Lundin, A. V. Sakharov, E. E. Zavarin, S. O. Usov, A. E. Nikolaev, M. A. Sinitsyn, N. A. Cherkashin, and S. Y. Karpov  Semiconductors 49, 1516–1521 (2015),

“ABC-model for interpretation of internal quantum efficiency and its droop in III-nitride LEDs: a review” by Sergey Karpov,  Opt Quant Electron 47, 1293–1303 (2015),

“Исследование влияния дизайна активной области монолитных многоцветных светодиодных гетероструктур на спектры и эффективность их излучения”, А.Ф. Цацульников, В.В. Лундин, А.В. Сахаров, Е.Е. Заварин, С.О. Усов, А.Е. Николаев, М.А. Синицын, Н.А. Черкашин, С.Ю. Карпов, Физика и техника полупроводников, 2015, том 49, вып. 11

“Polarization doping for III-nitride optoelectronics” by Oleg V. Khokhlev, Kirill A. Bulashevich, and Sergey Yu. Karpov, Phys. Status Solidi A 210, No. 7, 1369–1376 (2013), DOI: 10.1002/pssa.201228614

“Correlations between Epitaxy Recipe, Characteristics, and Performance of Nitride Light Emitting Diode Structures” by Eugene V. Yakovlev, Alexander S. Segal, Kirill A. Bulashevich, Sergey Yu. Karpov, and Roman A. Talalaev, JJAP 52 (2013) 08JB15, DOI: 10.7567/JJAP.52.08JB15. For more on the subject see also STREEM InGaN

“Simulation of light-emitting diodes for new physics understanding and device design” by K. A. Bulashevich, O. V. Khokhlev, I. Yu. Evstratov, and S. Yu. Karpov, “Light-Emitting Diodes: Materials, Devices and Applications for Solid- State Lighting XVI”, Proc. of SPIE, vol. 8278 (2012)

“Modeling of III-nitride Light-Emitting Diodes: Progress, Problems, and Perspectives” by Sergey Yu. Karpov, Proc. of SPIE, vol. 7939 (2011) 79391C / DOI 10.1117/12.872842

Effect of localized states on internal quantum efficiency of III-nitride LEDs”, Sergey Yu. Karpov, Phys. Status Solidi RRL 4, No.11, 320–322 (2010) / DOI 10.1002/pssr.201004325

Effects of electron and optical confinement on performance of UV laser diodes” by K.A. Bulashevich, M.S. Ramm, and S.Yu. Karpov,phys. stat. solidi (c) 6, No 2, 603–606 (2009)

Current spreading, heat transfer, and light extraction in multipixel LED array” by M.V. Bogdanov, K.A. Bulashevich, I.Yu. Evstratov, S.Yu. Karpov,  phys. stat. solidi (c) 5, No. 6, 2070–2072 (2008)

Is Auger recombination responsible for the efficiency rollover in III-nitride light-emitting diodes?” by K.A. Bulashevich and S.Yu. Karpov,  phys. stat. solidi (c) 5, No. 6, 2066–2069 (2008)

Assessment of various LED structure designs for high-current operation” by K.A. Bulashevich, M.S. Ramm, and S.Yu. Karpov, phys. stat. solidi (c) 6, No. S2, S804-S806 (2009).

Modelling study of MQW LED operation” by V.F. Mymrin, K.A. Bulashevich, N.I. Podolskaya, I.A. Zhmakin, S.Yu. Karpov, and Yu.N. Makarov,  phys. stat. sol. (c) 2, 2928-2931 (2005).


Conventional III-V compounds

“Critical aspects of AlGaInP-based LED design and operation revealed by full electrical-thermal-optical simulations” by Olga A. Fedorova, Kirill A. Bulashevich, ans Sergey Yu. Karpov, Vol. 29, No. 22 / 25 Oct 2021 / Optics Express 35792, (2021)

“Temperature effects on optical properties and efficiency of red AlGaInP-based light emitting diodes under high current pulse pumping” by Amit Yadav, Ilya E. Titkov, Grigorii S. Sokolovskii, Sergey Yu. Karpov, Vladislav V. Dudelev, Ksenya K. Soboleva, Martin Strassburg, Ines Pietzonka, Hans-Juergen Lugauer, and Edik U. Rafailov, JOURNAL OF APPLIED PHYSICS 124, 013103 (2018)

Effect of Free-Carrier Absorption on Performance of 808 nm AlGaAs-Based High-Power Laser Diodes” by K.A. Bulashevich, V.F. Mymrin, S.Yu. Karpov, Semcond. Sci. Technol. 22, No 5, 502-510 (2007)

ZnO-based devices and hybrid II-O/III-N devices

J.W. Mares, M. Falanga, A.V. Thompson, A. Osinsky, J.Q. Xie, B. Hertog, A. Dabiran, P.P. Chow, S. Karpov, and W.V. Schoenfeld, “Hybrid CdZnO/GaN quantum-well light emitting diodes”, J. Appl. Phys. 104, 093107 (2008).

K.A. Bulashevich, I.Yu. Evstratov, and S.Yu. Karpov, “Hybrid ZnO/III-nitride light-emitting diodes: modelling analysis of operation”, phys. stat. solidi (a) 204, No. 1, 241–245 (2007).

K.A. Bulashevich, I.Yu. Evstratov, V.N. Nabokov, S.Yu. Karpov, “Simulation of hybrid ZnO/AlGaN single-heterostructure light-emitting diode”, Appl. Phys. Lett 87, No. 24, 243502 (2005).