Microstructural studies of CdTe and InSb films grown by molecular beam epitaxy

Abstract

Epitaxial thin films of CdTe (1–5 μm) have been grown directly onto (001) InSb substrates or onto intermediate buffer layers of InSb (0.25–0.5 μm) by molecular beam expitaxy. Cross-sectional transmission electron microscopy and high-resolution transmission electron microscopy have been used to characterize the film and interfacial microstructures. Inferences about film quality were also compared with single-crystal x-ray rocking curve data and agreed well. Resulting microstructural features were correlated with various experimental growth parameters and substrate cleaning procedures. Results show that near-perfect CdTe films can be grown on InSb substrates, but film quality is critically dependent upon substrate cleaning. Other factors observed to influence defect formation in the films include growth rate, total growth time, or a change in growth rate during film growth. Extended defects which form include twins, line dislocations, or looplike defects. Lattice imaging has demonstrated the lattice matching across the InSb film/InSb substrate interface, despite the formation of In precipitates during the heat cleaning procedure.

Electronic Structure and Epitaxy of CdTe Shells on InSb Nanowires

“…The high defect density we observe in the CdTe shell of Figure 2e–h is consistent with reports on the presence of oxides on InSb surfaces affecting the quality of grown CdTe layers. [ 30 ] The nanowire cross‐section of Figure 2b with a uniformly thick CdTe shell of 7 nm indicates that this (dark‐contrast) oxide layer at the core–shell interface is present all‐around the InSb nanowire. Yet, high‐magnification images of the interface close to a corner and parallel to a facet (Figure 2c,d ) signify that the oxide layer is not fully formed as evidenced by the continuation of atomic columns locally from the core to the shell.…”

Electronic Structure and Epitaxy of CdTe Shells on InSb Nanowires

“…The presence of these oxides manifests as a dark contrast layer between the InSb core and the CdTe shell in scanning transmission electron microscopy (STEM) imaging (Figure 2a-d) and triggers the formation of defects (Figure 2e-h). The high defect density we observe in the CdTe shell of Figure 2e-h ing the quality of grown CdTe layers 30 . The nanowire cross-section of Figure 2b with a uniformly thick CdTe shell of 7 nm indicates that this (dark-contrast) oxide layer at the core-shell interface is present all-around the InSb nanowire.…”

Investigation of crystal growth on (111) InSb thin films to produce high performance Hall elements

“…[2][3][4][5][6][7] Low-cost substrates have been required to prepare devices like Hall elements using the high mobility of crystal InSb thin films. InSb crystal growth on mica has been investigated over a long time, 8 -12 but high mobility with excess In or low mobility with no or little excess In have resulted from these studies.…”