Nitride-based cascade near white light-emitting diodes

Chen, Chang-Hsiao; Chang, Shoou‐Jinn; Su, Yan–Kuin; Sheu, Jinn-Kong; Chen, J.F.; Kuo, Chih-Hung; Lin, Yu‐Cheng

doi:10.1109/lpt.2002.1012381

Cited by 79 publications

(41 citation statements)

References 16 publications

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“…For the red emission, the well composition was chosen to be In Ga N. A higher Indium fraction in the In Ga N well composition has been previously reported by Chen, et al [37].…”

Section: Qw Design For Emitting Near White Lightmentioning

confidence: 99%

Design of a GaN White Light-Emitting Diode Through Envelope Function Analysis

Khoshnegar

Sodagar

Eftekharian

et al. 2010

IEEE J. Quantum Electron.

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Abstract-In this paper, we present an envelope function analysis technique for the design of the emission spectra of a white quantum-well light-emitting diode (QWLED). The nanometric heterostructure that we are dealing with is a multiple QW, consisting of periods of three single QWs with various well thicknesses. With the aid of 6 6 Luttinger Hamiltonian, we employ the combination of two methods, k p perturbation and the transfer matrix method, to acquire the electron and hole wave functions numerically. The envelope function approximation was considered to obtain these wave functions for a special basis set. While adjacent valence sub-bands have been determined approximately, the conduction bands are approximated as parabolic. The effect of Stokes shift has also been taken into account. The dipole moment matrix elements for interband atomic transitions are evaluated via the correlation between the electron and hole envelope functions, for both orthogonal polarizations, thus simplifying the calculation of the photoluminescence intensity. Spatial variations in the hole/electron wave functions have been examined with the introduction of piezoelectric and spontaneous polarization internal fields. We theoretically establish the possibility of a highly efficient InGaN red emitter, resulting in a uniform luminescence in red, green, and blue emissions from a white light emitting diode by adjusting the material composition, internal field, and well thickness.Index Terms-Envelope function analysis, GaN, k p method, optical intensity spectrum, white LED.

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“…For the red emission, the well composition was chosen to be In Ga N. A higher Indium fraction in the In Ga N well composition has been previously reported by Chen, et al [37].…”

Section: Qw Design For Emitting Near White Lightmentioning

confidence: 99%

Design of a GaN White Light-Emitting Diode Through Envelope Function Analysis

Khoshnegar

Sodagar

Eftekharian

et al. 2010

IEEE J. Quantum Electron.

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“…sapphire (Al 2 O 3 ) (0001) substrates in an Emcore reactor. [7][8][9][10][11][12][13][14][15][16] The LED structure consists of a 50-nm-thick, GaN-nucleation layer grown at 560°C; a 3-m-thick, Si-doped, n-GaN buffer layer grown at 1,050°C; an unintentionally doped, InGaN/GaN MQW active region grown at 770°C; a 50-nm-thick, Mg-doped, p-Al 0.15 Ga 0.85 N electron-blocking layer grown at 1,050°C; and a 0.25-m-thick, Mg-doped, p-GaN contact layer also grown at 1,050°C. The InGaN/GaN MQW active region consists of five periods of 3-nm-thick, In 0.2 Ga 0.8 N-well layers and 10-nm-thick, GaN-barrier layers.…”

Section: Methodsmentioning

confidence: 99%

InGaN/GaN light-emitting diodes with a reflector at the backside of sapphire substrates

Hsu

Chang

et al. 2003

Journal of Elec Materi

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Nitride-based light-emitting diodes (LEDs) with a reflector at the backside of the sapphire substrates have been demonstrated. It was found that an SiO 2 /TiO 2 distributed-Bragg reflector (DBR) structure could reflect more downward-emitting photons than an Al-mirror layer. It was also found that the 20-mA output power was 2.76 mW, 2.65 mW, and 2.45 mW for the DBR LED, Al-reflector LED, and conventional LED, respectively. With the same 50-mA current injection, the integrated-electroluminescence (EL) intensity of a DBR LED and an Al-reflector LED was 19% and 15% larger than that observed from a conventional LED. INTRODUCTIONThe III-V nitrides have some unique properties, such as wide direct bandgap, high-thermal conductivity, and chemical stability. These properties have made III-V nitrides attractive in recent years. At room temperature, the bandgap energy of AlInGaN varies from 1.95 eV to 6.2 eV, depending on its composition. Therefore, III-V nitride semiconductors are particularly useful for light-emitting devices in the short wavelength region. 1-4 In fact, III-V nitridebased blue and green light-emitting diodes (LEDs) with an InGaN/GaN multiquantum-well (MQW) active region are now commercially available. These nitride-based blue and green LEDs could be used in versatile applications, such as full-color displays, full-color indicators, and traffic lights. The other potential application for nitride-based LEDs is lighting. Currently, light bulbs and fluorescent tubes are the most commonly used light sources in our daily life. However, these conventional light sources consume large power. The lifetime of these conventional light sources is also short. In contrast, nitride-based LEDs are much less power consuming and much more reliable. Thus, much attention has been focused on generating white light with nitride-based LEDs. Although it has been shown that we could combine nitride-based, blue-LED chips with yellow phosphors to generate white light, the output power of the nitride-based, white-LED lamps is still low. In other words, we need to further improve the output intensity of nitride-based, blue-LED chips before we can realize feasible nitride-based, white-LED lamps.Unlike laser diodes, photons generated from LED chips could be emitted in any direction. As a result, a large portion of photons emitted from a LED chip could be lost, particularly for those photons being emitted downward to the substrate. Thus, if we could effectively reflect those photons emitted downward, we should be able to enhance the LED-output intensity significantly. Because nitride-based LED structures are normally grown on transparent-sapphire substrates, we should be able to reflect downwardemitting photons by depositing an Al-mirror layer or a distributed-Bragg reflector (DBR) structure at the backside of the sapphire substrates. A highly reflective DBR mirror is formed from a repeated periodic stack of alternating high and low index quarterwavelength layers. To increase the reflectivity of a DBR structure, we need to precisely contr...

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“…[6][7][8][9][10][11][12][13][14] During growth, the chamber pressure was controlled at 100-300 torr. Trimethylaluminum (TMAl), trimethylgallium (TMGa), trimethylindium (TMIn), and ammonia (NH 3 ) were used as aluminum, gallium, indium, and nitrogen sources, respectively.…”

Section: Methodsmentioning

confidence: 99%

InGaN/GaN multiple quantum well green light-emitting diodes prepared by temperature ramping

Wen

Chang

et al. 2003

Journal of Elec Materi

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High-quality InGaN/GaN multiple-quantum well (MQW) light-emitting diode (LED) structures were prepared by a temperature-ramping method during metal-organic chemical-vapor deposition (MOCVD) growth. Two photoluminescence (PL) peaks, one originating from well-sensitive emission and one originating from an InGaN quasi-wetting layer on the GaN-barrier surface, were observed at room temperature (RT). The observation of high-order double-crystal x-ray diffraction (DCXRD) satellite peaks indicates that the interfaces between InGaN-well layers and GaN-barrier layers were not degraded as we increased the growth temperature of the GaN-barrier layers. With a 20-mA and 160-mA current injection, it was found that the output power could reach 2.2 mW and 8.9 mW, respectively. Furthermore, it was found that the reliability of the fabricated green LEDs prepared by temperature ramping was also reasonably good.

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Nitride-based cascade near white light-emitting diodes

Cited by 79 publications

References 16 publications

Design of a GaN White Light-Emitting Diode Through Envelope Function Analysis

Design of a GaN White Light-Emitting Diode Through Envelope Function Analysis

InGaN/GaN light-emitting diodes with a reflector at the backside of sapphire substrates

InGaN/GaN multiple quantum well green light-emitting diodes prepared by temperature ramping

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