The search for efficient but inexpensive photovoltaics over the past decade has been disrupted by advent of lead-halide perovskite solar cells. Despite impressive rises in performance, toxicity and stability concerns these materials have prompted a broad, interdisciplinary community across world to lead-free stable alternatives. A set such that recently gained attention are semiconductors CuI–AgI–BiI 3 phase space their derivatives. These include ternary silver bismuth iodide compounds (Ag...

In a wide variety of InGaN/GaN quantum well (QW) structures, defects are observed which consist trench partially or fully enclosing region the QW having altered emission properties. For various different defect morphologies, cathodoluminescence studies suggest that is redshifted in enclosed region. Based on transmission electron microscopy and atomic force data, we sub-surface structure consists basal plane stacking fault bounded by mismatch boundary, terminates at apex V-shaped trench.

InGaN-based light emitting diodes and multiple quantum wells designed to emit in the green spectral region exhibit, general, lower internal efficiencies than their blue-emitting counter parts, a phenomenon referred as “green gap.” One of main differences between green-emitting samples is that well growth temperature for structures at longer wavelengths, order reduce effects In desorption. this paper, we report on impact optical properties InGaN/GaN 460 nm 530 nm. It was found both sets...

The growth of >100-μm-thick diamond layers adherent on aluminum nitride with low thermal boundary resistance between and AlN is presented in this work. barrier was found to be the range 16 m2·K/GW, which a large improvement current state-of-the-art. While thick films failed adhere untreated films, treated hydrogen/nitrogen plasma retained layers. Clear differences ζ-potential measurement confirm surface modification due treatment. An increase non-diamond carbon initial grown pretreated seen...

Integrating diamond with GaN high electron mobility transistors (HEMTs) improves thermal management, ultimately increasing the reliability and performance of high-power high-frequency radio frequency amplifiers. Conventionally, an amorphous interlayer is used before growing polycrystalline onto in these devices. This layer contributes significantly to effective boundary resistance (TBReff) between HEMT diamond, reducing benefit heat spreader. Replacing a higher conductivity crystalline...

The impact of trench defects in blue InGaN/GaN light emitting diodes (LEDs) has been investigated. Two mechanisms responsible for the structural degradation multiple quantum well (MQW) active region were identified. It was found that during growth p-type GaN capping layer, loss part enclosed within a defect occurred, affecting top-most QWs MQW stack. Indium platelets and voids also to form preferentially at bottom presence high densities LEDs relate significant reduction photoluminescence...

Dislocations in undoped GaN move response to the in-plane tensile stress present during film growth. Dislocation movement growth relieves stress, produces arrays of a-type dislocations and reduces overall dislocation density, with preferential reduction (a+c)-type dislocations. However, Si-doping limits movement, limiting relief that develops reduction, probably due formation Si impurity atmospheres at Consequently, Si-doped films are under relatively greater compared grown similar...

Solving the green gap problem is a key challenge for development of future LED-based light systems. A promising approach to achieve higher LED efficiencies in spectral region growth III-nitrides cubic zincblende phase. However, metastability GaN along with crystal process often lead phase mixture wurtzite phase, high mosaicity, densities extended defects and point defects, strain, which can all impair performance emitting devices. X-ray diffraction (XRD) main characterization technique...

We present a multi-microscopy study of dislocations in InGaN, whereby the same threading dislocation was observed under several microscopes (atomic force microscopy, scanning electron cathodoluminescence imaging and spectroscopy, transmission microscopy), its morphological optical structural properties directly correlated. achieved this across an ensemble defects large enough to be statistically significant. Our results provide evidence that carrier localization occurs direct vicinity...

Hexagonal boron nitride (h-BN) is the only known material aside from graphite with a structure composed of simple, stable, noncorrugated atomically thin layers. While historically used as lubricant in powder form, h-BN layers have become particularly attractive an ultimately insulator, barrier, or encapsulant. Practically all emerging electronic and photonic device concepts currently rely on exfoliated small bulk crystallites, which limits dimensions process scalability. We here focus...

The slow progress in microstructural design for thin-film semiconductors remains a significant bottleneck transitioning emerging materials into practical applications. While machine learning (ML) shows great promise accelerating data analysis, effectively linking insights to actionable synthetic plans complex challenge that surpasses the capabilities of single model. We present Daisy Visual Intelligence Framework, computational platform using compound ML models semiconductor microstructure...

A systematic investigation of the optical properties β‐, α‐, and κ‐phase gallium oxide (Ga 2 O 3 ) polymorphs is conducted by UV–vis spectrophotometry through Swanepoel method temperature‐dependent photoluminescence. Using same approach apparatus allows similarities differences between these three phases to be directly established. Differences are observed, including refractive indices 1.89 (β), 2.00 (α), 1.85 (κ) bandgaps 4.99 eV 5.32 4.87 (κ). In luminescence studies, four emission peaks...

Abstract Two complementary localised density of states spectroscopies, Modulated Photo-Conductivity (MPC) and the Constant Photocurrent Method (CPM) are applied to Ga 2 O 3 thin films shown be sensitive carrier traps above below Fermi level, respectively. These techniques measure film directly, without requiring a Schottky or p-n junction, which may offer advantages over conventional in study high-resistivity semi-insulating materials. The benefits higher-resolution MPC analysis demonstrated.

Photoluminescence and electroluminescence measurements on InGaN/GaN quantum well (QW) structures light emitting diodes suggest that QWs with gross fluctuations in width (formed when, during growth, the InGaN is exposed unprotected to high temperatures) give higher room temperature efficiencies than continuous QWs. The efficiency does not depend growth of GaN barriers. Temperature-dependent results from activation energies for defect-related non-radiative recombination QW samples gaps. At...

Atom probe tomography (APT) has been used to characterize the distribution of In atoms within non-polar a-plane InGaN quantum wells (QWs) grown on a GaN pseudo-substrate produced using epitaxial lateral overgrowth. Application focused ion beam microscope enabled APT needles be prepared from low defect density regions sample. A complementary analysis was also undertaken QWs having comparable contents polar c-plane sample pseudo-substrates. Both frequency and modified nearest neighbor analyses...

The formation of trench defects is observed in 160 nm-thick InxGa1−xN epilayers with x ≤ 0.20, grown on GaN (0001) sapphire substrates using metalorganic vapour phase epitaxy. defect density increases increasing indium content, and high resolution transmission electron microscopy shows an identical structure to those previously InGaN quantum wells, comprising meandering stacking mismatch boundaries connected I1-type basal plane fault. These do not appear relieve in-plane compressive strain....

Low temperature atomic layer deposition was used to deposit α-Ga2O3 films, which were subsequently annealed at various temperatures and atmospheres. The phase is stable up 400 °C, also the that yields most intense sharpest reflection by x-ray diffraction. Upon annealing 450 °C above, material gradually turns into more thermodynamically ε or β phase. suitability of materials for solar-blind photodetector applications has been demonstrated with best responsivity achieved being 1.2 A W−1 under...

Diamond heat-spreaders for gallium nitride (GaN) devices currently depend upon a robust wafer bonding process. Bonding-free membrane methods demonstrate potential, however, chemical vapour deposition (CVD) of diamond directly onto III-nitride (III–N) heterostructure induces significant thermal stresses. In this work, these stresses are investigated using an analytical approach, numerical model and experimental validation. The caused by the mismatch in coefficient expansion (CTE) between...

We report on an approach to bring together single crystal metal catalyst preparation and graphene growth in a combined process flow using standard cold-wall chemical vapor deposition (CVD) reactor. employ sandwich arrangement between commercial polycrystalline Cu foil c-plane sapphire wafer show that close-spaced vacuum sublimation across the confined gap can result epitaxial, single-crystal Cu(111) film at high rate. The is scalable (we demonstrate 2″ scale) suppresses reactor contamination...

Atomic force microscopy (AFM) and scanning electron (SEM) with cathodoluminescence (CL) were performed on exactly the same defects in a blue-emitting InGaN/GaN multiple quantum well (QW) sample enabling direct correlation of morphology an individual defect its emission properties. The question are observed AFM SEM as trench partially or fully enclosing region QW having altered Their sub-surface structure has previously been shown to consist basal plane stacking fault (BSF) stack, mismatch...

We conducted a comprehensive investigation of dislocations in Al0.46Ga0.54N. Using aberration-corrected scanning transmission electron microscopy and energy dispersive X-ray spectroscopy, the atomic structure atom distribution at dislocation core have been examined. report that configuration AlGaN is consistent with other materials III-Nitride system. However, we observed dissociation mixed-type impeded by alloying GaN AlN, which confirmed our experimental observation Ga Al segregation...