STEM analysis of deformation and B distribution In nanosecond laser ultra-doped Si_1−xB_x

Abstract

We report on the structural properties of highly B-doped silicon (up to 10 at.% of active doping) realised by nanosecond laser doping. The crystalline quality, lattice deformation and B distribution profile of the doped layer are investigated by Scanning Transmission Electron Microscopy followed by High-Angle Annular Dark Field contrast studies and Geometrical Phase Analysis, and compared to the results of Secondary Ions Mass Spectrometry and Hall measurements. When increasing the active B concentration above 4 at.%, the fully strained, perfectly crystalline, Si:B layer starts showing dislocations and stacking faults. These only disappear around 8 at.% when the Si:B layer is well accommodated to the substrate. With increasing B incorporation, an increasing number of small precipitates is observed, together with filaments with a higher active B concentration and stacking faults. At the highest concentrations studied, large precipitates form, related to the decrease of active B concentration. The structural information, defect type and concentration, and active B distribution are connected to the initial increase and subsequent gradual loss of superconductivity.

Strain Measurement in Single Crystals by 4D-ED

“…The superconducting critical temperature of the sample is T c = 0.35 K, determined by low-temperature resistance vs. temperature measurements in an adiabatic demagnetization refrigerator. The superconducting critical temperature depends on both the active B concentration and the deformation of the Si:B layer [ 17 ]. Thus, a precise determination of the deformation profile in the layer thickness is essential for a correct understanding of the establishment of superconductivity in superconducting silicon.…”

Atomistic Insights into Ultrafast SiGe Nanoprocessing

“…In the context of group IV elemental and compound semiconductor processing, pulsed-LA applications are ubiquitous. ,, These include the fabrication of poly-Si thin-film transistors, − ultrashallow device junctions, ,− efficient contacts by silicidation, explosive crystallization, − strain, defect, , and dopant engineering. − Localized heating minimizes the risk of damaging sequentially integrated components of monolithic three-dimensional (3D) devices. − In optoelectronics, pulsed-LA is a key process for fabricating poly-Si displays, − thin metal-oxides, pure-carbon electrodes for touch screens or solar cells, and hyper-doped semiconductors for near-infrared photodetectors . It also allows strain, composition and morphology engineering of fiber-based photonic devices, and fabrication of heavily doped superconducting silicon for monolithic quantum device integration. ,− Despite all of these applications, understanding the ultrafast nonequilibrium kinetics of the liquid/solid interface in early stages of the process and correlating it to the postirradiation morphology and properties is challenging. This is because any experimental characterization, no matter how accurate, can only access the final state of the system.…”

“… 36 It also allows strain, composition and morphology engineering of fiber-based photonic devices, 8 and fabrication of heavily doped superconducting silicon for monolithic quantum device integration. 23 , 37 − 39 Despite all of these applications, understanding the ultrafast nonequilibrium kinetics of the liquid/solid interface in early stages of the process and correlating it to the postirradiation morphology and properties is challenging. This is because any experimental characterization, 5 no matter how accurate, can only access the final state of the system.…”