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Dispositivos Optoelectrónicos

Learn about various types of optoelectronic devices such as photodetectors, photodiodes, solar cells, LEDs, and optocouplers. Understand their working principles, spectral responses, frequency responses, and important factors. Explore applications in fiber optics, energy conversion, and more.

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Dispositivos Optoelectrónicos

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  1. Dispositivos Optoelectrónicos Dispositivos Semicoductores - DIEC/UNS

  2. Tipos • Fotodetectores: • Detectan cambios de energía fotónica, transformándolos en energía eléctrica • Celdas solares: • Transforman energía lumínica en eléctrica • LED / Diodos Laser: • Transforman energía eléctrica en energía lumínica • Optoacopladores Dispositivos Semicoductores - DIEC/UNS

  3. Dispositivos Semicoductores - DIEC/UNS

  4. 4.2x1014 Hz 6x1014 Hz Dispositivos Semicoductores - DIEC/UNS

  5. Fotodiodos p-n • Juntura p-n que permite penetración de luz en la vecindad de la unión metalúrgica • Absorción de luz crea pares hueco-electrón Dispositivos Semicoductores - DIEC/UNS

  6. Fotodiodos p-n • Portadores generados en la zona de vaciamiento son arrastrados por el E. • Tasa de Generación óptica: GL • Si W menor que la long. Del diodo, IL es independiente de la tensión aplicada y proporcional a la intensidad de luz Dispositivos Semicoductores - DIEC/UNS

  7. Respuesta espectral • Variación de IL con la longitud de onda de luz incidente Fotones generan pares h-e solo si Eph>EG. Para Si, EG = 1.12 eV, y λmax=1.1μm Dispositivos Semicoductores - DIEC/UNS

  8. Respuesta espectral • Variación de IL con la longitud de onda de luz incidente • Potencia lumínica es cte. Por ende, hay menos fotones de mayor energía (<λ) • A menor λ la luz penetra menos, y la generación se produce lejos de la zona de vaciamiento: se recombinan antes de llegar allí. Menor I Dispositivos Semicoductores - DIEC/UNS

  9. Fotodiodos p-n • Respuesta Frecuencial • Velocidad de respuesta ante cambios de la luz incidente • Fotodiodo p-n tiene capacidades limitadas • Portadores minoritarios deben difundir hasta la zona de vaciamiento: proceso lento • Máxima velocidad: decenas de Mhz Dispositivos Semicoductores - DIEC/UNS

  10. Fotodiodo p-i-n • Top semiconductor thin, to minimize absorption • i region is depleted • Most of the photocurrent is generated in the depletion region Dispositivos Semicoductores - DIEC/UNS

  11. Fotodiodo p-i-n • i region can be tailored for specific wavelengths • Frequency response is much better than Si diodes (most current is generated in the dep. Region) • Freq. response about GHz • Aplicaciones en fibra óptica requieren λ > 1.1μm, y menores bandgap (In Ga As) Dispositivos Semicoductores - DIEC/UNS

  12. Fotodiodos de Avalancha • Fotodiodos operados cerca del punto de ruptura inversa • Ganancia en la generación de portadores • Multiplicación de avalancha amplifica los portadores provocados por la luz Dispositivos Semicoductores - DIEC/UNS

  13. Fotodiodos • Factores Importantes • Velocidad de respuesta • Eficiencia cuántica: • relación entre fotones y pares h-e • Linealidad • Uniformidad espacial • Ruido oscuro (dark noise) Dispositivos Semicoductores - DIEC/UNS

  14. Hamamatsu model S2386 silicon photodiode Dispositivos Semicoductores - DIEC/UNS

  15. Dispositivos Semicoductores - DIEC/UNS

  16. Toshiba TPS850 Dispositivos Semicoductores - DIEC/UNS

  17. Celdas Solares Honda dream, the winning car in the 1996 World Solar Challenge. The custom made cells for the car are greater than 20% efficient. (Photograph PVSRC) Dispositivos Semicoductores - DIEC/UNS

  18. Celdas Solares • Junturas p-n de gran area • Design to minimize energy losses • Voc: open circuit voltage • Isc: short circuit current • Pmax = Im Vm Dispositivos Semicoductores - DIEC/UNS

  19. Celdas solares • Medida de desempeño: • eficiencia de conversión • Output from the sun • Area beyond λG is power lost cause it cannot be absorbed • 20% lost in Si, 35% in GaAs • The Eph>Eg energy adds kinetic energy (heat): • 40% in Si, 30% in GaAs Dispositivos Semicoductores - DIEC/UNS

  20. Celdas Solares Dispositivos Semicoductores - DIEC/UNS

  21. Celdas Solares • Top contact coverage of the cell surface can be minimised (although this may result in increased series resistance). • Anti-reflection coatings on the top surface of the cell. • Reflection reduced by surface texturing. • The solar cell can be made thicker to increase absorption • The optical path length may be increased by a combination of surface texturing and light trapping. http://www.udel.edu/igert/pvcdrom/index.html Dispositivos Semicoductores - DIEC/UNS

  22. Celdas Solares Area: 22cm2Efficiency: 23.5%Voc: 703 mVIsc: 914mAJsc: 41.3mAVmp: 600mVFF: 0.81Imp: 868 mA Dispositivos Semicoductores - DIEC/UNS

  23. Light Emitting Diode (LED) Definition: a semiconductor device that emits incoherent narrow-spectrum light when electrically biased in the forward direction Courtesy of Wikipedia http://en.wikipedia.org/wiki/LED Dispositivos Semicoductores - DIEC/UNS

  24. Principle • Forward bias injects majority carriers in opposite regions where they recombine • In indirect semiconductor (Si) recombination produces heat • In direct semiconductors (GaAs) recombination occurs from band to band and emits photons Dispositivos Semicoductores - DIEC/UNS

  25. Principle • Three requirements to produce visible LED • Direct semiconductor (Si, Ge, GaP, AlAs,SiC, excluded) • Bandgap between 1.77eV and 3.10eV (GaAs bandgap too small) • Able to allow pn junction diodes • Need for alloys Dispositivos Semicoductores - DIEC/UNS

  26. LED’s η = Photo power out/electrical power External quantum efficiency: is due to reflections in the Interface air-semiconductor Dispositivos Semicoductores - DIEC/UNS

  27. Light Emitting Diode (LED) • LED v.s. Incandescent (Edison’s lightbulb) and Flourescent Bulbs • Much longer life span (105 - 106 hrs v.s. 103 / 104 hrs) • Suitable for applications that are subject to frequent on-off cycling • Efficiency: better than incandescent but currently worse than flourescent bulbs Source: US Department of Energy http://www.netl.doe.gov/ssl/faqs.htm Dispositivos Semicoductores - DIEC/UNS

  28. LEDs for lighting • 12 Volt MR16 LED spotlight bulbs • Each LED spotlight has 20 ultrabright 15,000mcd LEDs producing a similar amount of light to a 20W halogen bulb • 1 Watt of power! Dispositivos Semicoductores - DIEC/UNS

  29. LED Efficiency • Internal Quantum Efficiency (ηint) • Definition: ratio of the number of electrons flowing in the external circuit to the number of photons produced within the device • Has been improved up to 80% • External Quantum Efficiency • Definition: The percentage of photons that can be extracted to the ambient. • Typically 1% ~ 10% • Limiting factor of LED efficiency • Improvement techniques: dome-shaped package, textured surface, photonic crystal, … Source: Lecture Note of “Optoelectronic Devices” (by Sheng-fu Horng, Dept. of Electrical Engrg, NTHU, Hsinchu, Taiwan) Dispositivos Semicoductores - DIEC/UNS

  30. LED Dispositivos Semicoductores - DIEC/UNS

  31. Optoacopladores • Aislación eléctrica entre dos circuitos. Comunicación óptica • Típicamente se utilizan haces de luz entre el rojo al infrarrojo Dispositivos Semicoductores - DIEC/UNS

  32. Características importantes: • Tensión de aislación • Buena relación de transferencia • Baja capacidad de acoplamiento • Imnunidad a interferencias Dispositivos Semicoductores - DIEC/UNS

  33. Dispositivos Semicoductores - DIEC/UNS

  34. Dispositivos Semicoductores - DIEC/UNS

  35. Dispositivos Semicoductores - DIEC/UNS

  36. Referencias • Robert F. Pierret, Semiconductor Device Fundamentals, Addison –Wesley, 1996. Capítulos 6, 9, 14. • Stanley G. Burns, Paul R. Bond, “Principles of Electronic Circuits”, PWS Publishing Company, 1997. Capítulo 3. Dispositivos Semicoductores - DIEC/UNS

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