Design of AlGaN-based quantum structures for low threshold UVC lasers

Abstract

The influence of the polarization field on the emission properties of the AlGaN-based quantum structures grown on AlN substrates was investigated as a function of well width, barrier width, and barrier height. A thin AlGaN well and a thin AlN barrier design reduced the polarization field to ∼0.5 MV/cm, resulting in an ultralow laser threshold of 3 kW/cm2 in an optically pumped configuration. These experimental results were used to validate the simulation. In the next step, a structure with Al0.7Ga0.3N barriers was designed to support carrier injection with a minimal loss in optical performance. This structure showed a threshold of 7 kW/cm2 under optical pumping and an estimated threshold current of 8 kA/cm2 for the electric injection.

Recent Progress on Aluminum Gallium Nitride Deep Ultraviolet Lasers by Molecular Beam Epitaxy

“…[102][103][104] As a consequence, these large polarization fields induce a strong QCSE in AlGaN QWs, which, in turn, leads to a number of adverse effects such as a reduced carrier radiative recombination efficiency and a redshift of the emission wavelength. [33,[105][106][107] To mitigate QCSE, the MBE growth of nonpolar and/or semipolar AlGaN thin films has been investigated. [108][109][110][111][112][113] Sawicka et al performed a comparative study of AlGaN/GaN QWs grown on semipolar (2021), nonpolar m-plane (1010), and polar (0001) c-plane GaN substrates under N-rich conditions by PAMBE.…”

“…Today, the majority studies of AlGaNbased DUV lasers are on AlGaN quantum well (QW) structures; and such laser structures are predominantly grown by metal-organic chemical vapor deposition (MOCVD). [23][24][25][26][27][28][29][30][31][32][33][34][35][36][37][38][39][40][41] In the past, several groups have intensively studied optically pumped AlGaN-based QW laser structures grown by MOCVD on saphire, aluminum nitride (AlN)-on-saphire templates, and bulk AlN substrates. They have demonstrated significant progress in reducing the lasing threshold, which was lowered from several MW cm À2 in the first structures grown on c-plane sapphire substrates to the recently achieved values of less than 10 kW cm À2 in the structures with lasing around 263 nm, grown on bulk AlN substrates.…”

“…They have demonstrated significant progress in reducing the lasing threshold, which was lowered from several MW cm À2 in the first structures grown on c-plane sapphire substrates to the recently achieved values of less than 10 kW cm À2 in the structures with lasing around 263 nm, grown on bulk AlN substrates. [25,33] However, the thresholds at shorter wavelengths have remained high, typically larger than 100 kW cm À2 and up to MW cm À2 . [35,40,41] Such optically pumped laser structures generally consist of AlGaN multiple QWs, AlGaN waveguides, and high-Al-content AlGaN cladding layers.…”

“…With the use of bulk AlN substrates, AlGaN DUV lasers with low thresholds are indeed achieved. [23,25,[27][28][29][30][31][32][33]57] However, the high cost and low availability have remained to be the limiting factors for the wide usage of bulk AlN substrates for the AlGaN DUV laser development. In addition, the incorporation of the C impurity in AlN substrates might be another issue as the defect luminescence occurs in the DUV band.…”

Особенности структурных и оптических свойств InGaN-слоев, полученных методом МПЭ ПА с импульсной подачей потоков металлов

“…Эти прямозонные полупроводники охватывают широкий диапазон длин волн от ультрафиолетового (УФ) до инфракрасного (ИК) [1]. Тем не менее на текущий момент коммерчески освоенным является довольно узкий диапазон от ближнего УФ (> 300 нм) до видимого диапазона с длинами волн ∼ 500 нм [2,3]. Продвижение в область больших длин волн сопровождается существенным падением внутренней и внешней квантовых эффективностей излучения, что в совокупности с тем, что AlInGaPисточники становятся неэффективными на длинах волн короче красного света, формирует так называемую " зеленую" щель [3,4].…”