scholarly journals Performance deterioration of GaN-based laser diode by V-pits in the upper waveguide layer

Nanophotonics ◽  
2020 ◽  
Vol 9 (3) ◽  
pp. 667-674
Author(s):  
Feng Liang ◽  
Degang Zhao ◽  
Desheng Jiang ◽  
Wenjie Wang ◽  
Zongshun Liu ◽  
...  
Keyword(s):  
Quantum Wells ◽  
Current Density ◽  
Optical Loss ◽  
Optical Power ◽  
Threshold Current ◽  
Threshold Current Density ◽  
Device Performance ◽  
Nonradiative Recombination ◽  
Calculation Results ◽  
Performance Deterioration

AbstractThe effect of V-pits in the upper waveguide (UWG) on device performance of GaN-based laser diodes (LDs) has been studied. Experimental results demonstrate that in comparison with the LDs with u-In0.017Ga0.983N/u-GaN multiple UWG or u-In0.017Ga0.983N one, the LDs with a single u-GaN UWG has the best device performance. They have a smaller threshold current density, and a larger and more stable output optical power. The lowest threshold current density is as low as 1.3 kA/cm2, and the optical power reaches to 2.77 W. Furthermore, atomic force microscopy suggests that the deterioration of device performance of former kinds of devices may be attributed to the increase of V-pits’ size and quantity in the undoped-In0.017Ga0.983N UWG layer, and these V-pits could introduce more nonradiative recombination centers and exacerbate the inhomogeneity of injection current. Moreover, theoretical calculation results indicate that the increase of leakage current and optical loss are additional reasons for the device performance deterioration, which may be caused by a reduction of the potential barrier height for electrons in the quantum wells and by an increased background electron concentration in UWG.

scholarly journals Рабочие характеристики полупроводниковых лазеров на квантовых ямах в зависимости от ширины волноводной области

2021 ◽  
Vol 55 (12) ◽  
pp. 1229
Author(s):  
З.Н. Соколова ◽  
Н.А. Пихтин ◽  
С.О. Слипченко ◽  
Л.В. Асрян
Keyword(s):  
Output Power ◽  
Current Density ◽  
Optical Loss ◽  
Optical Power ◽  
Pump Current ◽  
Threshold Current ◽  
Threshold Current Density ◽  
Operating Characteristics ◽  
Optical Confinement ◽  
Cladding Layers

Operating characteristics of semiconductor quantum well (QW) lasers are theoretically studied in terms of the thickness of the waveguide region [optical confinement layer (OCL)]. We calculate the maximum modal gain, optical confinement factor (in QW, OCL, and cladding layers), threshold current density, electron and hole densities (in QW and OCL), internal optical loss (in QW, OCL, and cladding layers), internal differential quantum efficiency, stimulated and spontaneous recombination currents, and output optical power of the laser as functions of the OCL thickness. It is shown that up to the pump current density 50 kA/cm2 the output power of the considered lasers depends only slightly on the OCL thickness in the range of thicknesses 1.5–2.8 m. This result is important for designing high brightness lasers as broadened waveguides are used in such lasers to attain low beam divergence. At high pump current densities, the output power is shown to have a maximum as a function of the OCL thickness.

InGaN/GaN/AlGaN-Based Leds and Laser Diodes

1998 ◽  
Vol 537 ◽  
Author(s):  
S. Nakamura ◽  
M. Senoh ◽  
S. Nagahama ◽  
N. Iwasa ◽  
T. Matushita ◽  
...  
Keyword(s):  
Quantum Well ◽  
Leakage Current ◽  
Output Power ◽  
Current Density ◽  
Laser Diodes ◽  
Threshold Current ◽  
Threshold Current Density ◽  
Nonradiative Recombination ◽  
Window Region ◽  
Recombination Centers

AbstractInGaN quantum-well-structure blue LEDs were grown on epitaxially laterally overgrown GaN (ELOG) and sapphire substrates. The output power of both LEDs was as high as 6 mW at a current of 20 mA. The LED on sapphire had a considerable amount of leakage current in comparison with that on ELOG. These results indicate that In composition fluctuation is not caused by threading dislocations (TDs), free carriers are captured by radiative recombination centers before they are captured by nonradiative recombination centers in InGaN, and that the dislocations form the leakage current pathway in InGaN. Red LED with an emission peak wavelength of 650 nm was fabricated by increasing the In composition and thickness of InGaN well layer. When the laser diodes (LD) was formed on the GaN layer above the SiO2 mask region, the threshold current density was as low as 3 kAcm-2. When the LD was formed on the window region, the threshold current density was as high as 6 to 9 kAcm-2. There is a possibility that a leakage current due to a large number of TDs caused the high threshold current density on the window region. InGaN multi-quantum-well (MQW) structure LDs grown on the ELOG substrate showed an output power as high as 420 mW under RT-CW operation. The longest lifetime of 9,800 hours at a constant output power of 2 mW was achieved. The InGaN MQW LDs were fabricated on a GaN substrate. The fundamental transverse mode was observed up to an output power of 80 mW.

Low-threshold-current-density 1.5 mu m lasers using compressively strained InGaAsP quantum wells

1992 ◽  
Vol 4 (1) ◽  
pp. 10-13 ◽  
Author(s):  
J.S. Osinski ◽  
Y. Zou ◽  
P. Grodzinski ◽  
A. Mathur ◽  
P.D. Dapkus
Keyword(s):  
Quantum Wells ◽  
Current Density ◽  
Threshold Current ◽  
Threshold Current Density ◽  
Low Threshold

Low Threshold Current Density 1.5 μm Strained-MQW Laser by n-Type Modulation-Doping

2005 ◽  
Vol 475-479 ◽  
pp. 1663-1668 ◽  
Author(s):  
Rui-ying Zhang ◽  
Wei Wang ◽  
Fan Zhou ◽  
Jing Bian ◽  
Ling-juan Zhao ◽  
...  
Keyword(s):  
Quantum Wells ◽  
Current Density ◽  
Threshold Current ◽  
Threshold Current Density ◽  
Multiple Quantum ◽  
Modulation Doping ◽  
Doping Effects ◽  
Low Threshold ◽  
Current Densities ◽  
First Time

1.5µm n-type modulation-doping InGaAsP/InGaAsP strained multiple quantum wells grown by low pressure metalorganic chemistry vapor decomposition technology is reported for the first time in the world. N-type modulation-doped lasers exhibit much lower threshold current densities than conventional lasers with undoped barrier layers. The lowest threshold current density we obtained was 1052.5 A/cm2 for 1000 µm long lasers with seven quantum wells. The estimated threshold current density for an infinite cavity length was 94.72A/cm2/well, reduced by 23.3% compared with undoped barrier lasers. The n-type modulation doping effects on the lasing characteristics in 1.5µm devices have been demonstrated.

Gas source MBE growth of 1.3μm-InAsP/InGaAsP quantum wells GRINSCH laser showing low threshold current density and high output power

1999 ◽  
Vol 201-202 ◽  
pp. 909-913 ◽  
Author(s):  
Hin Yiu Chung ◽  
Georgi Stareev ◽  
Jürgen Joos ◽  
Matthias Golling ◽  
Jürgen Mähnß ◽  
...  
Keyword(s):  
Quantum Wells ◽  
Current Density ◽  
Threshold Current ◽  
Threshold Current Density ◽  
High Output Power ◽  
Mbe Growth ◽  
Gas Source ◽  
Low Threshold ◽  
Gas Source Mbe ◽  
High Output

scholarly journals InGaN/GaN/AlGaN-Based Leds and Laser Diodes

1999 ◽  
Vol 4 (S1) ◽  
pp. 1-17 ◽  
Author(s):  
S. Nakamura ◽  
M. Senoh ◽  
S. Nagahama ◽  
N. Iwasa ◽  
T. Matushita ◽  
...  
Keyword(s):  
Quantum Well ◽  
Leakage Current ◽  
Output Power ◽  
Current Density ◽  
Laser Diodes ◽  
Threshold Current ◽  
Threshold Current Density ◽  
Nonradiative Recombination ◽  
Window Region ◽  
Recombination Centers

InGaN quantum-well-structure blue LEDs were grown on epitaxially laterally overgrown GaN (ELOG) and sapphire substrates. The output power of both LEDs was as high as 6 mW at a current of 20 mA. The LED on sapphire had a considerable amount of leakage current in comparison with that on ELOG. These results indicate that In composition fluctuation is not caused by threading dislocations (TDs), free carriers are captured by radiative recombination centers before they are captured by nonradiative recombination centers in InGaN, and that the dislocations form the leakage current pathway in InGaN. Red LED with an emission peak wavelength of 650 nm was fabricated by increasing the In composition and thickness of InGaN well layer. When the laser diodes (LD) was formed on the GaN layer above the SiO2 mask region, the threshold current density was as low as 3 kAcm−2. When the LD was formed on the window region, the threshold current density was as high as 6 to 9 kAcm−2. There is a possibility that a leakage current due to a large number of TDs caused the high threshold current density on the window region. InGaN multi-quantum-well (MQW) structure LDs grown on the ELOG substrate showed an output power as high as 420 mW under RT-CW operation. The longest lifetime of 9,800 hours at a constant output power of 2 mW was achieved. The InGaN MQW LDs were fabricated on a GaN substrate. The fundamental transverse mode was observed up to an output power of 80 mW.

Analysis of Optical Gain of Strained Wurtzite InxGa1-xN/GaN Quantum Well Lasers

1997 ◽  
Vol 482 ◽  
Author(s):  
T. C. Chong ◽  
Y. C. Yeo ◽  
M. F. Li ◽  
W. J. Fan
Keyword(s):  
Quantum Wells ◽  
Mole Fraction ◽  
Current Density ◽  
Compressive Strain ◽  
Optical Gain ◽  
Numerical Approach ◽  
Threshold Current ◽  
Threshold Current Density ◽  
Analytical Approximations ◽  
Suitable Combination

AbstractThe valence subband structures, density-of-states, and optical gain of (0001) wurtzite (WZ) InxGa1-xN/GaN quantum wells (QWs) are studied using a numerical approach without analytical approximations. We used the effective-mass parameters of GaN and InN derived using the Empirical Pseudopotential Method. By varying the well width and mole fraction of In in the well material, the effects of quantum confinement and compressive strain are studied. A narrower well width and a higher In mole fraction in the well lead to TE enhancement and TM suppression of the optical gain. From the relationship between the optical gain and the radiative current density, we obtain the transparent current density for a single QW to be 200 A/cm2. Further, we analyze the InxGa1-xN/GaN/AlGaN separate confinement heterostructure multiple-QW laser structure. It is shown that a suitable combination of well width and number of QWs should be selected in optimizing the threshold current density in such MQW lasers

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