Large-area total-thickness imaging and Burgers vector analysis of dislocations in β -Ga2O3 using bright-field x-ray topography based on anomalous transmission

Abstract

Using bright-field x-ray topography based on anomalous transmission (AT), we have demonstrated the first large-area total-thickness imaging of dislocations in β-Ga2O3 at the substrate scale. The dislocation images were acquired from the entire 10 mm × 15 mm × 680 μm (001)-oriented substrate prepared by edge-defined film-fed growth (EFG) by stitching together hundreds of topographic images, each recorded with the forward-diffracted beam in the Laue geometry for g = 020, 0–20, 022, and 400, under the conditions in which AT occurred. Dislocations distributed over the entire crystal volume were imaged as long as their Burgers vectors ( b) were not orthogonal to the g-vectors. The results of the g· b analysis of the dislocation contrasts clearly revealed three major dislocation types that were numerically dominant in the EFG crystal: (i) b-axis screw-type dislocations with b∥ ξ∥[010] ( ξ is the unit vector of line direction), (ii) b-axis edge-type dislocations with b∥[001] and ξ∥[010], and (iii) curved mixed-type dislocations lying on the (001) planes with b∥[010]. Based on their b - and ξ-vectors, types (i) and (ii) were attributed to dislocations that propagated during EFG pulling up along the [010] direction, while type (iii) was attributed to dislocations generated through glide in the [010](001) slip system under stress. The extent to which AT can manifest itself is explained by using the effective absorption coefficient calculated for the above g-vectors based on dynamical x-ray diffraction theory.

Plasma-free anisotropic selective-area etching of β-Ga 2 O 3 using forming gas under atmospheric pressure

“…The ( 02) plane is parallel to the [010] axis and perpendicular to the (100) plane, which is known for its lowest surface energy density [ 26 ]. This orientation coincides with the primary dislocation and void/nanopipe directions within the crystal [ 36–38 ], making it particularly suitable for vertical anisotropic etching. This avoids undesired crystal defects on the surface, favoring vertical trench and fin device applications [ 25 ].…”

Lattice misorientation at domain boundaries in β‐Ga2O3 single‐crystal substrates observed via synchrotron radiation X‐ray diffraction imaging and X‐ray reticulography

“…This requires several key technologies to suppress the generation of lattice defects. Typical lattice defects in bulk substrates include dislocations, [12][13][14][15][16] stacking faults, [17][18][19] voids, 10,[20][21][22] and domain boundaries (DBs). 6 Compared to the other three major defect types, DB has drawn little attention from researchers.…”

Epitaxial relationship of NiO on ( 1̅ 02) β-Ga2O3

“…Twin domains are formed during homoepitaxy on the (100) and ( 201) substrates, 15,16) while many dislocations and voids exist along [010] to appear on the (010) surface. 17) These domain boundaries, dislocations, and voids can act as leakage paths and hinder the application of vertical power devices. Therefore, it is still worthwhile to explore substrate orientation in order to create a pn heterojunction with an interface consisting of a low-index ccp plane, while addressing the problems associated with defects in β-Ga 2 O 3 .…”