- 标题
- 摘要
- 关键词
- 实验方案
- 产品
-
Defect generation by nitrogen during pulsed sputter deposition of GaN
摘要： Pulsed sputter deposition has been demonstrated to be a viable process for the growth of high quality GaN and InGaN/GaN LEDs. It enables the fabrication of nitride LEDs with a red emission wavelength at large areas. In this study, we explore details on the epitaxial sputter deposition of GaN with a particular emphasis on ion damage. By changing the argon to nitrogen ratio, we adjust the growth mode from island to layer growth. TEM revealed speckles in the epitaxial GaN, which could be identi?ed as isolated basal stacking faults, acting as non-radiative recombination centers. Using Monte Carlo methods, we modeled the energies of backscattered and sputtered atoms in order to get information on the ion damage mechanisms. Considering the collisions on the way from the target to the substrate, we found energetic nitrogen to induce the speckles. A shielding mechanism based on metallic gallium has been identi?ed, leading to the strongly increased luminescence quality in comparison to the non-shielded material.
关键词： GaN,pulsed sputter deposition,stacking faults,luminescence,ion damage
更新于2025-09-23 15:21:01
-
Atomic-scale quantitative analysis of implanted Mg in annealed GaN layers on free-standing GaN substrates
摘要： Achieving efficient p-type conduction in Mg-implanted GaN depends largely on postimplantation annealing conditions. Here, we study the effect of postimplantation annealing on the evolution of defects and their interactions with implanted Mg ions by using scanning transmission electron microscopy and atom probe tomography. We found that Mg clusters start to form by annealing the implanted sample above 1000 °C. In addition to the Mg clusters, stacking faults form at an annealing temperature of 1300 °C. The Mg concentrations of about 2–3 orders of magnitude higher than implanted Mg were segregated at the stacking faults. Nanobeam electron diffraction analysis revealed no distinct phase other than GaN formed at the Mg-enriched defects, suggesting that Mg is substituted for Ga in the GaN lattice at the edge of the stacking faults.
关键词： stacking faults,Mg clusters,postimplantation annealing,scanning transmission electron microscopy,Mg-implanted GaN,atom probe tomography
更新于2025-09-12 10:27:22
-
Effect of stacking faults and surface roughness on the thermal conductivity of InAs nanowires
摘要： Low thermal conductivity and high power factor are desirable for thermoelectric materials. These properties can be achieved by patterning devices into nano-structures such as nanowires (NWs). The thermal conductivity can be further reduced by altering the NW geometry through the introduction of surface roughness (SR) or stacking faults (SFs). In this paper, relaxation times for scattering of phonons at SFs and SR are developed to accurately compute the impact of both effects on the thermal conductivity of InAs NWs with different diameters. It is found that similar reductions of the thermal conductivity can be obtained with SFs instead of SR. For the shortest possible distance between SFs along a NW, the room temperature thermal conductivity can be reduced to 25% compared to an ideal NW. For a NW with rough surface, a more than 80% decrease of the thermal conductivity is possible for specific roughness profiles. All available experimental data on the lattice thermal conductivity of InAs NWs confirm the theoretical models and simulation results.
关键词： surface roughness,thermal conductivity,phonon scattering,stacking faults,InAs nanowires
更新于2025-09-10 09:29:36