Yield shear stress dependence on nanoindentation strain rate in bulk GaN crystal

Abstract

The strain rate controlled nanoindentation was performed in c‐plane (0001) and m‐plane (10–10) GaN crystals. The indentation velocity was ranged from 0.16 to 800 nm/s. The significant displacement bursts were detected after every perfect elastically deformations and they allowed us to calculate the maximum shear stress τmax. The τmax dependences on strain rate in two crystal orientations involved that the two perpendicular compressions induced the same plastic deformation mechanism. Comparing the obtained τmax with the Peierls potential and maximum shear stress in each slip system, {10–11} 〈11–20〉 dislocation nucleation may support the origin of the plastic deformation in GaN crystal. (© 2011 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)

Evidence of lattice tilt and slip in m-plane InGaN/GaN heterostructure

“…The f10 20g prism plane with h11 20i-type slip direction has the lowest value. 21 The slip should occur via this prism plane in the m-plane (Fig. 3).…”

Origin of a Nanoindentation Pop-in Event in Silicon Crystal

“…The phenomenon observed for numerous metallic crystals [2][3][4], GaN [5], SiC [6], Si-nanoobjects [7][8][9], is linked to nucleation of dislocations in the virtually defect-free crystal nano-volume stressed under an indenter. The first pop-in in the P-h graph usually defines incipient plasticity of the probed material, which relates to either dislocation nucleation [2][3][4][5][6][7][8][9] or pressure-induced phase transformation, such as in the case of GaAs [9,11]. However, the pop-ins recorded for silicon seem different, since their number and location are neither predictable nor repeatable [12][13][14].…”

FEM thermal and stress analysis of bonded GaN-on-diamond substrate

“…The maximum stress appears in the center of the transition layer where the channel temperature is 423.15K, this is because higher channel temperature causes larger mismatch. The yield stress for GaN is roughly 11.5 GPa, 20 and for polycrystalline diamond is larger than 15Gpa. 21,22 The yield stress of Si 3 N 4 is between these two values.…”