Abstract
We report on a novel quantum well intermixing (QWI) technique that induces a large degree of bandgap blueshift in the InGaP/InAlGaP laser structure. In this technique, high external compressive strain induced by a thick layer of SiO2 cap with a thickness ≥1 μm was used to enhance QWI in the tensile-strained InGaP/InAlGaP quantum well layer. A bandgap blueshift as large as 200 meV was observed in samples capped with 1-μm SiO2 and annealed at 1000 °C for 120 s. To further enhance the degree of QWI, cycles of annealing steps were applied to the SiO2 cap. Using this method, wavelength tunability over the range of 640 nm to 565 nm (∼250 meV) was demonstrated. Light-emitting diodes emitting at red (628 nm), orange (602 nm), and yellow (585 nm) wavelengths were successfully fabricated on the intermixed samples. Our results show that this new QWI method technique may pave the way for the realization of high-efficiency orange and yellow light-emitting devices based on the InGaP/InAlGaP material system.
Highlights
There has been strong interest in visible laser diodes (LDs), which have several important applications in solid-state lighting,1 photodynamic therapy (PDT),2 medicine, and visible light communication.3 The available highefficiency visible LDs are primarily made of III-V and III-N material systems
We report on a novel quantum well intermixing (QWI) technique that induces a large degree of bandgap blueshift in the InGaP/InAlGaP laser structure
Our results show that this new QWI method technique may pave the way for the realization of high-efficiency orange and yellow light-emitting devices based on the InGaP/InAlGaP material system
Summary
There has been strong interest in visible laser diodes (LDs), which have several important applications in solid-state lighting, photodynamic therapy (PDT), medicine, and visible light communication. The available highefficiency visible LDs are primarily made of III-V and III-N material systems. There has been strong interest in visible laser diodes (LDs), which have several important applications in solid-state lighting, photodynamic therapy (PDT), medicine, and visible light communication.. The available highefficiency visible LDs are primarily made of III-V and III-N material systems. These light-emitting devices are either InGaN/GaN-based, covering the violet to green wavelengths ($405–530 nm), or InGaP/InAlGaP-based, covering the red (632–690 nm) wavelengths. High-efficiency LDs in the green-yellow-orange (GYO) (550–620 nm) wavelengths are still not available. Large strain and indium segregations in InGaN/GaN prevent the growth of high-quality LDs with emissions beyond 540 nm.. For the InGaP/InAlGaP material system, more Al incorporation in the active layer shortens the emission wavelength; oxygen-related defects severely reduce their efficiency.. Large strain and indium segregations in InGaN/GaN prevent the growth of high-quality LDs with emissions beyond 540 nm. For the InGaP/InAlGaP material system, more Al incorporation in the active layer shortens the emission wavelength; oxygen-related defects severely reduce their efficiency. In addition, the small band offset between the quantum well (QW) and barriers leads to low carrier confinement and large carrier leakage current.
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