High Q microcavity light emitting diodes with buried AlN current apertures (original) (raw)
Related papers
Optically Pumped GaN-based Vertical Cavity Surface Emitting Lasers: Technology and Characteristics
Japanese Journal of Applied Physics, 2007
We review the fabrication technology and performance characteristics of optically pumped GaN-based vertical cavity surface emitting lasers (VCSELs). Two types of VCSELs with different microcavity structures are described. First type of VCSEL has a hybrid microcavity structure that consists of an epitaxially grown AlN/GaN distributed Bragg reflector (DBR), a GaN active layer with InGaN/GaN multiple quantum wells (MQWs), and a Ta 2 O 5 /SiO 2 dielectric DBR. Second type of VCSEL has a dielectric DBR microcavity structure that has a similar InGaN/GaN MQWs active layer sandwiched in two dielectric DBRs formed by Ta 2 O 5 /SiO 2 and TiO 2 /SiO 2 . Both types of VCSELs achieved laser action under optical pumping at room temperature with emission wavelength of 448 and 414 nm for hybrid DBR VCSEL and dielectric DBR VCSEL, respectively. Both lasers showed narrow emission linewidth with high degree of polarization and large spontaneous emission coupling factors of about 10 À2 . In addition, a high characteristic temperature of over 240 K was measured, and a distinct spatially inhomogeneous emission pattern was observed.
CW lasing of current injection blue GaN-based vertical cavity surface emitting laser
Applied Physics Letters, 2008
Here, we report the cw laser operation of electrically pumped GaN-based vertical cavity surface emitting laser ͑VCSEL͒. The GaN-based VCSEL has a ten-pair InGaN / GaN multiple quantum well active layer embedded in a GaN hybrid microcavity of 5 optical thickness with two high reflectivity mirrors provided by an epitaxially grown AlN / GaN distributed Bragg reflector ͑DBR͒ and a Ta 2 O 5 / SiO 2 dielectric DBR. cw laser action was achieved at a threshold injection current of 1.4 mA at 77 K. The laser emitted a blue wavelength at 462 nm with a narrow linewidth of about 0.15 nm. The laser beam has a divergence angle of about 11.7°with a polarization ratio of 80%. A very strong spontaneous coupling efficiency of 7.5ϫ 10 −2 was measured.
Characteristics of Current-Injected GaN-Based Vertical-Cavity Surface-Emitting Lasers
IEEE Journal of Selected Topics in Quantum Electronics, 2011
This paper reviews the fabrication technology and performance characteristics of current-injected GaN-based vertical-cavity surface-emitting lasers (VCSELs) with hybrid distributed Bragg reflectors (DBRs). The GaN-based VCSEL consists of a ten-pair Ta 2 O 5 /SiO 2 top DBR, a 7λ-thick optical cavity embedded with 10 InGaN/GaN multiquantum wells, and a 29-pair AlN/GaN bottom DBR. Lasing action is observed under continuous-wave operation at room temperature. The laser characteristics, such as temperature-dependent laser threshold current, emission wavelength, and spontaneous emission coupling factors, have been measured and discussed.
Japanese Journal of Applied Physics, 2006
In this paper, we report a GaN-based microcavity light-emitting diode (MCLED) which is composed of 25 pairs of highreflectivity GaN/AlN distributed Bragg reflector (DBR) and 6 pairs of ex-situ deposited SiO 2 /TiO 2 dielectric mirrors. The electroluminescence peak of this structure matched well with the high reflectance area of the top and bottom DBRs, and shows a narrow emission of approximately 6.7 nm. The fabricated device also shows a more excellent performance on the stability of the emission peak wavelength while varying injection current density and operating temperature than a regular LED.
GaN-based vertical cavity lasers with semiconductor/dielectric and all dielectric reflectors
Gallium Nitride Materials and Devices VIII, 2013
GaN-based vertical cavity structures containing bottom AlN/GaN DBRs with top dielectric DBRs on freestanding c-GaN and all dielectric DBRs on GaN on c-sapphire were investigated. Epitaxial lateral overgrowth (ELO) technique allowed the use of both top and bottom all dielectric reflector stacks without substrate removal and the fabrication of the active region containing InGaN multiple quantum wells entirely on the nearly defect-free laterally grown wing regions to avoid nonradiative centers caused by extended and point defects. Compared with the cavity containing hybrid-DBRs on freestanding GaN, the cavity with all dielectric DBRs exhibited quality factors up to 1200 at high optical excitation and an order of magnitude lower stimulated emission threshold density (nearly 5 μJ/cm 2 ). Vertical to lateral growth ratio for ELO could be enhanced up to 5 by increasing the V/III ratio and employment of NH 3 modulation, which minimizes the use of dry etching to reduce the cavity thickness and therefore is promising for high quality vertical cavities with all dielectric DBRs.
GaN-Based High-$Q$ Vertical-Cavity Light-Emitting Diodes
IEEE Electron Device Letters, 2000
We report a fabrication and demonstration of a GaN-based high-Q vertical-cavity light-emitting diode (VCLED). The GaN VCLED is composed of a 25-pair high-reflectivity (98%) GaN/AlN distributed Bragg reflector (DBR), an eight-pair SiO 2 /Ta 2 O 5 dielectric DBR (99%), and a three-λ optical thickness InGaN/GaN active region. It shows a very narrow linewidth of 0.52 nm, corresponding to a cavity Q-value of 895 at a driving current of 10 mA and a dominant emission peak wavelength at 465.3 nm. In addition, this VCLED emission linewidth continues to decrease with an increasing injection current, suggesting a possible realization of GaN-based vertical-cavity surface emitting lasers. Index Terms-GaN, light-emitting diode (LED), vertical cavity, vertical-cavity LED (VCLED).
Effects of built-in polarization on InGaN-GaN vertical-cavity surface-emitting lasers
IEEE Photonics Technology Letters, 2000
We investigate the effect of built-in spontaneous and piezoelectric polarization on the internal device physics of current-injected GaN-based vertical-cavity surface-emitting lasers (VCSELs) with strained InGaN quantum wells. Advanced device simulation is applied to a previously manufactured device design featuring dielectric mirrors and an indium-tin-oxide current injection layer. Contrary to common perception, we show: 1) that only a small fraction of the built-in quantum-well polarization is screened at typical injection current densities and 2) that the polarization of the AlGaN electron stopper layer has a strong effect on the VCSEL threshold current which can be partly compensated for by higher p-doping.
IEEE Photonics Technology Letters, 2000
The characteristics of a GaN-based vertical-cavity surface-emitting laser (VCSEL) with 25 pairs AlN-GaN distributed Bragg reflector (DBR) and eight pairs Ta 2 O 5 -SiO 2 DBR was investigated and analyzed under the optical pumping at room temperature. The GaN-based VCSEL emits a blue wavelength at 448 nm with a linewidth of 0.17 nm with a near-field emission spot diameter of about 3 m. The laser beam has a near linear polarization with a degree of polarization of about 84%. The laser shows a high spontaneous emission coupling efficiency of about 5 10 2 and a high characteristic temperature of about 244 K. Index Terms-AlN, distributed Bragg reflector (DBR), GaN, vertical-cavity surface-emitting laser (VCSEL).
Springer Series in Optical Sciences, 2012
This chapter first briefly reviews the background of the development of GaN-based edge-emitting lasers and key technical issues and approaches. Then we present the design considerations and fabrication technology for the development of GaN-based vertical-cavity surface-emitting lasers (VCSELs). The technical issues and approaches for fabricating high-quality and high-reflectivity GaN distributed Bragg reflectors (DBRs) are discussed. The trade-offs among the three kinds of GaN microcavity structures are compared. Fabrication processes and key performance characteristics of hybrid and double dielectric microcavities for optically pumped GaN VCSELs are presented. The key approaches to achieve electrically pumped GaN VCSELs are analyzed and recent developments in electrically pumped GaN VCSELs are described. The future prospects of enhancing the GaN VCSEL performance and operation temperature are discussed. Finally the emerging applications for nitridebased VCSELs are briefly described.