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AlGaN-based deep-ultraviolet light emitting diodes (DUV-LEDs) with thin p-GaN capping layer have been one of the most promising configurations, thanks to their excellent light extraction potential, which are, however, generally accompanied by insufficient hole supply. In this work, multi-graded p-AlGaN layers are adopted as an integrated p-type region, in which the electron blocking layer (EBL) is taken off to promote the carrier transport. The experimental results show that both the operation voltage and light output power of the DUV-LEDs are improved compared to the traditional ones, leading to a remarkable increase (by 114%) in their wall-plug efficiency. Further analysis confirms that the integrated p-type region serving as the hole supply layer helps holes to avoid the barrier between the p-GaN and integrated p-type region during their transport, and the absence of the EBL further eliminates part of the obstacles for hole drifting, giving rise to an enhanced hole concentration in quantum wells. Meanwhile, thanks to the modulation of the negative polarization induced bulk charges for conduction band, which is introduced within the integrated p-type region, the electron leakage is effectively suppressed even without the EBL, thus improving the device performance dramatically. [ABSTRACT FROM AUTHOR]

We report the design, growth, fabrication, and characterization of a GaAs-based resonant-cavity-enhanced (RCE) GaInNAs photodetector operating at 1.55 μm. The structure of the device was designed using a transfer-matrix method (TMM). By optimizing the molecular-beam epitaxy growth conditions, six GaInNAs quantum wells were used as the absorption layers. Twenty-five (25)- and 9-pair GaAs/AlAs-distributed Bragg reflectors were grown as the bottom and top mirrors. At 1.55 μm, a quantum efficiency of 33% with a full width at half maximum of 10 nm was obtained. The dark current density was 3×10-7 A/cm2 at a bias of 0 V and 4.3×10-5 A/cm2 at a reverse bias of 5 V. The primary time response measurement shows that the device has a rise time of less than 800 ps. [ABSTRACT FROM AUTHOR]

InGaAsNSb/GaAs quantum wells (QWs) were grown by solid-source molecular-beam epitaxy using a N[sub 2] radio frequency plasma source. The effect of adding Sb during growth of InGaAsN/GaAs QWs was studied. X-ray diffraction, reflection high-energy electron diffraction and transmission electron microscopy studies indicate that Sb suppresses the three-dimensional growth and improves the interface of the QWs. X-ray diffraction and secondary ion mass spectroscopy analysis show that Sb gets incorporated into the quantum well, which becomes a quinternary compound that was previously unexplored. The introduction of Sb during growth of InGaAsN/GaAs QWs significantly enhances the optical properties of the QWs. 1.53 μm room-temperature photoluminescence was obtained from InGaAsNSb/GaAs QWs, which demonstrates the potential of fabricating 1.55 μm InGaAsNSb/GaAs QW lasers for long-haul applications. © 2001 American Institute of Physics. [ABSTRACT FROM AUTHOR]

Describes molecular beam epitaxial growth of InGaAsN:Sb/GaAs quantum wells for long-wavelength semiconductor lasers. Enhancement in the optical properties of the quantum wells revealed by photoluminescence; X-ray diffraction and reflection high-energy electron diffraction analyses.

We demonstrate the growth of full-composition-graded InxGa1−xN (0 ≤ x ≤ 1) on a GaN/sapphire template using plasma-assisted molecular beam epitaxy. Composition of indium in InxGa1−xN films is controlled by growth temperature and gallium flux. It was found that In composition increases gradually from x = 0 (GaN) to x = 1 (InN) along the growth direction accompanied by a gradual strain relaxation. At the initial stage of growth, multiple quantum wells like structures with low and high In composition InxGa1−xN layers are spontaneously formed, effectively relaxing the in-plane strain. Finally, the graded InxGa1−xN film exhibits a broadband absorption covering the full solar spectrum, which provides a promising path for the design and production of graded InxGa1−xN based photovoltaic devices. [ABSTRACT FROM AUTHOR]

1.3 μm InGaAsN:Sb/GaAs multiple-quantum-well laser diodes have been grown by solid-source molecular-beam epitaxy using Sb as a surfactant. A low threshold of 1.1 kA/cm2 was achieved for broad-area laser diodes under pulsed operation at room temperature. High-temperature device characterization revealed characteristic temperatures (T[sub 0]) of 92 and 54 K for operating temperatures below and above 75 °C, respectively, as well as a lasing-wavelength temperature dependence of 0.36 nm/ °C. © 2000 American Institute of Physics. [ABSTRACT FROM AUTHOR]

Developing efficient active region structures with low sensitivity to threading dislocation density (TDD) is of great technical significance for AlGaN-based deep ultraviolet (DUV) light-emitting devices. Here, we propose an active region strategy by introducing bunching effect to form self-assembled sidewall quantum wells (SQWs) with much stronger carrier confinement, resulting in a significant enhancement of internal quantum efficiency (from 46% to 59%) compared to the commonly adopted multiple quantum wells (MQWs) due to the lower sensitivity to TDD. As a demo, an AlGaN-based DUV light-emitting diode (LED) with the proposed active region involving both SQWs and MQWs presents dual-band emission and a consequent 68% enhancement in light output power compared to the DUV-LED with only MQWs as the active region, suggesting that the proposed architecture is fully suitable for the development of high performance DUV light-emitting devices even based on poor or medium quality materials. [ABSTRACT FROM AUTHOR]

The influence of nonradiative recombination on the photoluminescence (PL) decay dynamics in GaInNAs/GaAs quantum wells is studied by time-resolved photoluminescence under various excitation intensities. It is found that the PL decay process strongly depends on the excitation intensity. In particular, under the moderate excitation levels the PL decay curves exhibit unusual nonexponential behavior and show a convex shape. By introducing a new parameter of the effective concentration of nonradiative recombination centers into a rate equation, the observed results are well simulated. The cw PL data further demonstrate the nonradiative recombination effect on the optical properties of GaInNAs/GaAs quantum wells. [ABSTRACT FROM AUTHOR]

Starting from the growth of high-quality 1.3 μm GaInNAs/GaAs quantum well (QW), the QW emission wavelength has been extended up to 1.55 μm by a combination of lowering growth rate, using GaNAs barriers and incorporating some amount of Sb. The photoluminescence properties of 1.5 μm range GaInNAsSb/GaNAs QWs are quite comparable to the 1.3 μm QWs, revealing positive effect of Sb on improving the optical quality of the QWs. A 1.59 μm lasing of a GaInNAsSb/GaNAs single-QW laser diode is obtained under continuous current injection at room temperature. The threshold current density is 2.6 kA/cm2 with as-cleaved facet mirrors. [ABSTRACT FROM AUTHOR]