Open AccessEffect of germanium auto‐diffusion on the bond lengths of Ga and P atoms in GaP/Ge(111) investigated by using X‐ray absorption spectroscopy
Author(s) -
Roychowdhury R.,
Rajput P.,
Kumar Shailendra,
Kumar R.,
Bose A.,
Jha S. N.,
Sharma T. K.,
Dixit V. K.
Publication year - 2021
Publication title -
journal of synchrotron radiation
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.172
H-Index - 99
ISSN - 1600-5775
DOI - 10.1107/s160057752001629x
Subject(s) - bond length , band gap , materials science , diffusion , germanium , atom (system on chip) , spectroscopy , absorption (acoustics) , absorption spectroscopy , molecular physics , crystallography , diffraction , analytical chemistry (journal) , chemistry , crystal structure , optics , optoelectronics , silicon , physics , chromatography , quantum mechanics , computer science , embedded system , composite material , thermodynamics
The germanium auto‐diffusion effects on the inter‐atomic distance between the nearest neighbors of the Ga atom in GaP epilayers are investigated using high‐resolution X‐ray diffraction (HRXRD) and X‐ray absorption spectroscopy. The GaP layers grown on Ge (111) are structurally coherent and relaxed but they show the presence of residual strain which is attributed to the auto‐diffusion of Ge from the results of secondary ion mass spectrometry and electrochemical capacitance voltage measurements. Subsequently, the inter‐atomic distances between the nearest neighbors of Ga atom in GaP are determined from X‐ray absorption fine‐structure spectra performed at the Ga K ‐edge. The estimated local bond lengths of Ga with its first and second nearest neighbors show asymmetric variation for the in‐plane and out‐of‐plane direction of GaP/Ge(111). The magnitude and direction of in‐plane and out‐of‐plane microscopic residual strain present in the GaP/Ge are calculated from the difference in bond lengths which explains the presence of macroscopic residual tensile strain estimated from HRXRD. Modified nearest neighbor configurations of Ga in the auto‐diffused GaP epilayer are proposed for new possibilities within the GaP/Ge hetero‐structure, such as the conversion from indirect to direct band structures and engineering the tensile strain quantum dot structures on (111) surfaces.