scholarly journals Threshold increase and lasing inhibition due to hexagonal-pyramid-shaped hillocks in AlGaN-based DUV laser diodes on single-crystal AlN substrate

2021 ◽  
Author(s):  
Maki Kushimoto ◽  
Ziyi Zhang ◽  
Yoshio HONDA ◽  
Leo John Schowalter ◽  
Chiaki Sasaoka ◽  
...  
Keyword(s):  
Imaging Techniques ◽  
Laser Diodes ◽  
Optical Excitation ◽  
Threshold Current ◽  
Excitation Power ◽  
Threshold Current Density ◽  
Excitation Power Density ◽  
Threshold Excitation ◽  
The Difference ◽  
Hexagonal Pyramid

Abstract The presence of hexagonal-pyramid-shaped hillocks (HPHs) in AlGaN epitaxial films affects device character- istics; this effect is significant in DUV laser diodes (LDs) on AlN substrates, where the presence of HPHs under the p-electrode increases the threshold current density and inhibits the lasing. In this study, we investigated the difference between the lasing characteristics of LDs with and without HPHs. It was found that in the presence of HPHs, the threshold excitation power density increased and the slope efficiency decreased by optical excitation. To investigate the cause of these phenomena, we performed structural, optical, and electrical analyses of the HPHs. Various imaging techniques were used to directly capture the characteristics of the HPHs. As a result, we concluded that HPHs cause the degradation of LD characteristics due to a combination of structural, optical, and electrical factors.

Surface Emission of InxGa1-x N/GaN Espaliers Grown by MOCVD under Different Optical Excitation

2012 ◽  
Vol 442 ◽  
pp. 393-397
Author(s):  
You Zhang Zhu ◽  
Yan Liu ◽  
Hong Xia Wang ◽  
Zhen Sun ◽  
Jin She Yuan
Keyword(s):  
Power Density ◽  
Chemical Vapor ◽  
Optical Excitation ◽  
Excitation Power ◽  
Organic Chemical ◽  
Light Sources ◽  
Excitation Power Density ◽  
Transmission Spectra ◽  
Surface Emission ◽  
The Difference

Photoluminescence properties of InGaN film grown on sapphire substrates by metal organic chemical vapor deposition(MOCVD) was experimentally Investigation. The x-ray diffraction(XRD), transmission spectra, PL spectrum were used. The result of XRD shows that the mole composition of In in the InGaN film is estimated be 0.2 approximately. The band gap of the sample is calculated to be 2.66eV. A clear oscillation from F-P cavity could be observed on transmission spectra. There are three main peaks from the surface emission InGaN espaliers being excited on different light sources and different excitation power density. which can be explained the broad PL come from the difference of In composition modulated by was modulated due to F-P cavity arising from surface of sample. . It is found that there is some relationship between the position of the peaks in the PL spectra, the wavelength and intensity of power density and the F-P cavity.PACS: 73.61.

Latest developments in Blue-Violet Laser Diodes grown by Molecular Beam Epitaxy

2004 ◽  
Vol 831 ◽  
Author(s):  
V. Bousquet ◽  
M. Kauer ◽  
K. Johnson ◽  
C. Zellweger ◽  
S.E. Hooper ◽  
...  
Keyword(s):  
Molecular Beam Epitaxy ◽  
Molecular Beam ◽  
Multiple Quantum Well ◽  
Laser Diodes ◽  
Threshold Current ◽  
Threshold Current Density ◽  
Multiple Quantum ◽  
Pulsed Injection ◽  
Current Duration ◽  
Multiple Quantum Well Laser

ABSTRACTWe report on recent results obtained for InGaN multiple quantum well laser diodes grown by ammonia based Molecular Beam Epitaxy. The laser diodes were grown on freestanding GaN substrates and operated at room temperature under pulsed current injection conditions. For devices with improved p-type doping a threshold current density of 6.7kA.cm−2 was measured for a current pulse duration of 200ns and an operating temperature of 3.9°C. A duty cycle up to 50% with a pulsed injection current duration of 500μs was also achieved at 3.9°C.

PERFORMANCE ENHANCEMENT OF InGaN-BASED LASER DIODES USING A STEP-GRADED AlxGa1-xN ELECTRON BLOCKING LAYER

2011 ◽  
Vol 20 (03) ◽  
pp. 515-520
Author(s):  
Y. ZHANG ◽  
J.-P. LIU ◽  
T.-T. KAO ◽  
S. KIM ◽  
Y.-C. LEE ◽  
...  
Keyword(s):  
Continuous Wave ◽  
Performance Enhancement ◽  
Laser Diodes ◽  
Threshold Current ◽  
Threshold Current Density ◽  
Device Performance ◽  
Blocking Layer ◽  
Electron Blocking Layer ◽  
Electron Accumulation ◽  
Continuous Wave Operation

A step-graded Al x Ga 1- x N electron blocking layer (EBL) is introduced to the InGaN -based edge-emitting blue-violet laser diode (LD) structure to suppress the undesired built-in interface polarization charges. When compared to a conventional abrupt Al 0.18 Ga 0.82 N EBL design, the step-graded Al x Ga 1- x N EBL design may help reduce the electron accumulation at the edge of the active region and hence improve the quantum efficiency in LD operation. The effects of the step-graded Al x Ga 1- x N EBL on the fabricated device performance are also investigated. LDs with the step-graded Al x Ga 1- x N EBL demonstrated significantly reduced threshold current density and increased slope efficiency under the continuous-wave operation.

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