Gallium vacancies related yellow luminescence in N-face GaN epitaxial film

Investigation on the origin of luminescence quenching in N-polar (In,Ga)N multiple quantum wells

“…Depending on the area observed, we estimated that the uncertainty of these values is not higher than a factor 2, and therefore, these defect densities are found in agreement with the nominal defect densities of the substrates and with the one observed directly after growth by AFM. 20 Concerning the C level in our samples, we have no data available. However, we estimated an uppermost dislocation density of 1 Â 10 8 /cm 2 in these samples, that is comparable to the one in Ga-polar samples.…”

Role of Si and C Impurities in Yellow and Blue Luminescence of Unintentionally and Si-Doped GaN

“…For example, it is widely known that the yellow luminescence (YL) band peaking around 2.2 eV and the blue luminescence (BL) band peaking around 2.9 eV from the GaN films are mainly caused by the carrier recombination between the donor–acceptor pairs (DAPs). However, the mechanism of the YL band is quite complicated [10,11,12,13,14,15], and the origin of the blue luminescence (BL) band peaking around 2.9 eV in GaN grown without intentional acceptor doping is also in dispute [16,17,18,19,20,21]. Which impurity and/or native point defect introduces the donor–acceptor pair luminescence has not been confirmed affirmatively.…”

Comparison of stress states in GaN films grown on different substrates: Langasite, sapphire and silicon

“…The inevitable heteroepitaxy of GaN on foreign substrates like sapphire, Si or SiC results in stress, and generates high density of threading dislocations (TD, $ 10 8 -10 10 cm À 2 ), cracks and other defects (stacking faults, voids, inversion domains, point defects) due to the large lattice mismatch and thermal expansion coefficient incompatibility, which deteriorates the optical and electrical properties of GaN-based devices [5,6]. Ever since Amano et al successfully demonstrated the growth of high quality crack-free GaN epilayers on sapphire substrate using an AlN buffer layer a variety of strain compensating layers like low-temperature GaN, SiN, AlN-GaN superlattices, AlGaN and rare earth oxides have been used to mitigate the stress and to reduce the TD density in GaN epilayers [1,[7][8][9][10]. Use of these buffer layers, to some extent, has shown considerable improvement in the crystalline quality of GaN epilayers and their device performances, yet there still exist many defects and thus, the growth of high-quality GaN raises many interrogations and requires further research.…”

“…Gallium nitride (GaN) has long been viewed as a promising semiconductor due to its fascinating intrinsic properties like wide direct band gap (3.4 eV), strong binding energies, excellent thermal stability and conductivity, mechanical and chemical robustness, which triggered a fast technological progress in the fabrication of electronics and optoelectronic devices such as high brightness light emitting diodes (LEDs), high-electron-mobility transistors as well as high temperature, high frequency, and high power semiconductor devices [1][2][3][4]. Despite the remarkable progresses made in the commercialization of GaN systems achievement of their full potential has however been limited due to the lack of native/lattice-matched substrates.…”