Optically pumped lasing at 300.4 nm in AlGaN MQW structures grown by plasma‐assisted molecular beam epitaxy on c‐Al₂O₃

Abstract

We have demonstrated optically pumped room-temperature pulse lasing at 300.4 nm from an AlGaN-based multiplequantum-well (MQW) structure grown by plasma-assisted molecular beam epitaxy on a c-sapphire substrate. The lasing was achieved at the threshold peak power of $12 MW/cm 2 . The MQW structure involved AlGaN/AlN short-period superlattices to decrease the threading dislocation densities from 10 11 down to 10 9 -10 10 cm À2 . Studies of time-resolved photoluminescence (TRPL) spectra and cw PL temperature dependences (10-300 K) of different MQW structures, as well as numerical calculations of the optical gain and confinement in the laser structure allowed us to conclude about the optimum design of AlGaN-based MQW structures for the lower threshold UV lasing.

Plasma‐assisted molecular beam epitaxy of AlGaN heterostructures for deep‐ultraviolet optically pumped lasers

“…Optimization of the AlGaN‐based QW structures for optically pumped UV‐lasing was performed in several stages in order to decrease the threshold power density and achieve the sub‐300‐nm wavelength range. The first QW structures of a nonoptimized design ( i.e ., without a standard waveguide layer) and having low structural quality (a TD density of about 10 10 cm −2 ) demonstrated the UV‐lasing ( λ = 300.4 nm) at rather high threshold power density ∼12 MW cm −2 , which is close to the catastrophic optical degradation of the material 64. Development of a separate‐confinement heterostructure design with the asymmetric position of a MQW active region in the waveguide layer and employing different TD filtering techniques (see Section 3.2) resulted in a significant decrease of the threshold power density down to 800 kW cm −2 10.…”

Deep-ultraviolet integrated photonic and optoelectronic devices: A prospect of the hybridization of group III–nitrides, III–oxides, and two-dimensional materials

“…Poor current conduction has also prevented the achievement of electrically pumped QW lasers operating in the UV-B (280-315 nm) and UV-C (200-280 nm) bands [566][567][568][569][570] . Because they are still being extensively investigated in research laboratories around the globe, the development of DUV LDs is still in its infancy stage, as these researchers almost exclusively attempt to exploit the Al x Ga 1−x N material system [571,572] .…”

Stimulated emission in AlGaN/AlGaN quantum wells with different Al content

“…Such an unusual position of the SE band has been previously observed in InGaNbased [13][14][15][16] and AlGaN-based 9,10,16 materials and has been attributed to SE originating from localized states. 10,13,15,16 Screening of the built-in electric field has also been suggested as an additional mechanism of the blue shift of SE band. 16 Different influence of localization in the samples with different indium content has been previously observed in InGaN LEDs.…”

“…However, there are only a few reports on stimulated emission under photoexcitation in AlGaN-based multiple quantum wells (MQWs) [5][6][7][8][9][10][11][12] with the shortest wavelength of SE band at room temperature at 241 nm. 6,7 Most of the reports on SE in AlGaN are focused on the optimization of growth conditions and structure design.…”

“…6,7 Most of the reports on SE in AlGaN are focused on the optimization of growth conditions and structure design. [8][9][10][11] MQWs grown on different substrates, AlN, 5,12 SiC, 6,7 and sapphire, [8][9][10] have been under study. Only very few papers report on the investigations of the temperature 6 or polarization 7,11,12 properties of the SE band.…”