Grain Boundaries in Semiconductors

Abstract

The sections in this article are Introduction Grain Boundary Structure: Concepts and Tools Grain Boundary Definitions Geometrical Concepts Dislocation Model Primary Dislocation Network Secondary Dislocation Network Stress Field Associated with Grain Boundaries Structural Unit Descriptions Stick and Ball Structural Units Energetic Structural Units Algebraic Structural Units Structural Units and Dislocations/Disclinations The Limits of the Structural Unit Descriptions Computer Simulation Techniques Methods Boundary Conditions Interaction Laws Experimental Techniques Grain Boundary Structure: Experience and Simulation Results Silicon and Germanium Tilt Grain Boundaries Twist Grain Boundaries Diamond Si C Ga As Ga N Al N Ni O Comments on Grain Boundary Structures Electrical Properties of Grain Boundaries Introduction Electrical Effects Induced by Grain Boundaries Electronic States Associated with a Grain Boundary Potential Barrier and Transport Properties Dynamic Properties and Recombination Properties Experimental Methods for Measuring the Grain Boundary Electrical Activity Methods Based on Transport Transient Methods Correlation Between Electrical Activity and Structure Transport Experiments in Bicrystals Transient Properties Measured on Bicrystals Emission and Capture Properties of Silicon and Germanium Grain Boundaries Polycrystalline Silicon Intrinsic or Extrinsic Origin of Electrical Activity of Grain Boundaries Impurity Segregation and Precipitation Induced by Grain Boundaries Introduction Dopant Elements Oxygen and Sulfur Transition Elements Copper Nickel Iron Conclusions Mechanical Properties of Grain Boundaries in Semiconductors Introduction Interaction Between Dislocations and Grain Boundaries Dislocation Absorption Dislocation Transmission Across Grain Boundaries Grain Boundaries as a Dislocation Source Grain Boundary Dislocation Movement Physical Consequences Grain Boundary Migration Recovery of the Grain Boundary Structure and Cavitation Deformation Modelling Conclusions

Hidden defects in silicon nanowires

“…Fortunately, the slice is quite thin and, as shown on high resolution STEM images (figures 3(b), (c), (d) and (f)), all the observed grains are observed along a [011] direction. Five different types of orientations are found in figure 3 hereafter = 3 are also encountered (figure 3(d)) [32] and a series of defects on alternating {111} and {112} planes can lead to an average {100} plane (figure 3(d)) in grain B, which is close to an average {110} plane in grain A. As can be seen in figure 3(b), the FIB milling has increased the thickness of the amorphous layer at the surface of the NW (about 40 nm of amorphous layer can be seen, where it has a thickness of 2 nm in traditional images of NWs), but it cannot have introduced all the observed defects, because these defects were also present in figure 2 and such defects are never observed on FIB-prepared specimens of bulk silicon.…”

“…Fortunately, the slice is quite thin and as evidenced on high resolution STEM images ( are encountered (Fig. 3d) 32 and a series of defects on alternating {111} and {112} planes can lead to an average {100} plane (Fig. 3d) in grain B, wich is close to an average {110} plane in grain A.…”

Gettering Processes and the Role of Extended Defects

“…These are predominantly 3 twin boundaries, higher-order twins ( 9,27,81) and so-called random boundaries that also include small-angle grain boundaries [214]. From detailed high-resolution TEM studies it is now well established that highly symmetric coincidence grain boundaries are built up from structural units that avoid the formation of dangling bonds [215], which implies that the electrical activity should be small. In fact, for such high-symmetry boundaries there is good evidence for the electrical activity to be of extrinsic origin, i.e., due to accumulation of impurities there.…”

Misorientation and Temperature Dependence of Small Angle Twist Grain Boundaries in Silicon: Atomistic Simulation of Directional Growth

“…Silicon has attracted huge applications in photovoltaics and semiconductors over the past decades. The applications include multi-crystalline and mono-like silicon solar cells, − where grain boundaries (GBs) play a dominant role in the material properties. What we know about GBs are their unique impacts on functional (e.g., electronic transports and thermal conductivity) and structural (e.g., microstructure stability and mechanical strength) properties of materials. − It has been experimentally and numerically shown that different GB structures and energies significantly affect atomic bond environments, impurity segregation, , defect sink and interactions, , radiation damage annealing, , local kinetics, and thermodynamics. , Therefore, learning GB properties is the prerequisite to accessing the high performance of related silicon materials.…”