Study of Ge Threading Dislocations Post Growth Treatments

Abstract

Threading dislocation density (TDD) of epitaxial Ge layer on Si was explored by defect etching. Ge samples were etched by chromium free Dash etching solution, and the influence of post process annealing was studied. The first part of this work deals with the comparison of two characterization methods for TDD: AFM of etch pits and TEM. The etch rate and morphology of Dash solution on pure Ge is introduced. The morphology and density of the etched pits is introduced for various annealing conditions after the growth.

Dislocations in Crystalline Silicon Solar Cells

“…[6] The so-called dash-etching, containing HF and nitric acid (HNO 3 ), can reveal dislocations in different orientations, but it requires a long time to etch. [7] Due to the strong corrosiveness of HNO 3 , several etchants that utilize oxidants instead of HNO 3 have been developed, such as Sirti etchant (HF mixed with chromium oxide [CrO 3 ] in water), Wright etchant (CrO 3 and Cu(NO 3 ) 2 •3H 2 O in a mixture of water, HNO 3 , HF, and acetic acid), and Secco etchant (K 2 Cr 2 O 7 in water mixed with HF). [8][9][10] The Sirti etchant and Wright etchant form uneven etching pits depending on the surface or grain orientation.…”