Hetero-Twinning in Chemical Epitaxy of PbS Thin Films on GaAs Substrates

Abstract

Twinning, i.e., inversion of atomic stacking sequence along a specific crystallographic axis, is a commonly occurring phenomenon in thin film growth. A very large number of reports have shown cases of conventional twinning within a single polycrystalline phase, where the plane of contact between the two twinned parts, called the composition plane, coincided with the twinning plane. Here we show for the first time twinning in heteroepitaxial monocrystalline PbS semiconductor thin films that are deposited from aqueous solutions under ambient conditions. The chemically deposited films show a distinct, well-defined "hetero-twin" relationship with monocrystalline GaAs substrates of various orientations: (100), (111), and (110). Notably, the same twin relationship, with the (111) twin plane and [1̅ 1̅ 2] twinning direction was observed in all studied cases regardless of the composition plane.

Heteroepitaxy of Large-Area, Monocrystalline Lead Halide Perovskite Films on Gallium Arsenide

“…Specifically, the PbS layer grows up along its [110] direction on GaAs (100), and in-plane directions [001] and [11̅0]­are parallel to GaAs [011] and [011̅], respectively. This observation is consistent with previous reports . While there is only an ∼5% mismatch between PbS [11̅0] and GaAs [011̅], the mismatch between PbS [001] and GaAs [011] is as large as ∼50%.…”

“…Based on the XRD results obtained in Figure , we established a 3D atomic scheme to interpret the MAPbBr 3 /PbS/GaAs epistructure, illustrated in Figure . This illustration is based on crystal orientations deduced by X-ray characterization, and consistent with the perovskite/PbS and PbS/GaAs interfacial structures described in previous reports. , According to Figure d–f, the epitaxial relation is MAPbBr 3 (100) || PbS (110) || GaAs (100), MAPbBr 3 [001] || PbS [001] || GaAs [011], and MAPbBr 3 [010] || PbS [11̅0] || GaAs [011̅]. Specifically, the PbS layer grows up along its [110] direction on GaAs (100), and in-plane directions [001] and [11̅0]­are parallel to GaAs [011] and [011̅], respectively.…”

Large-scale self-assembled epitaxial growth of highly-ordered three-dimensional micro/nano single-crystalline PbSe pyramid arrays by selective chemical bath deposition

“…The arrayed nature and narrow size distribution of the assembled structures provide an excellent platform for advancing applications and assembly processes reliant on the unique properties of PbSe. It is predictable that epitaxial pyramid arrays are likely to be obtained using an elegant single step chemical epitaxy deposition (without MBE-PbSe seed layer) on GaAs or surface treatment Si substrates by COA mechanism based on the Dr Golan's studies [30][31][32][33][34][35] on the lead-salt epitaxial thin films from CBD.…”

“…These results show that a higher quality mono-crystalline (111) PbSe epitaxial layer could be obtained from CBD method by growing on (111) MBE-PbSe epitaxial buffer layer. The single-crystal lead salt films obtained from CBD method were reported by Golan [30][31][32][33][34][35].…”

A New Solid Solution Approach for the Study of Self-Irradiating Damage in non-Radioactive Materials

“…The procedure we developed to achieve this goal takes advantage of the chemical similarity of the quasi-stable 232 Th (1.4 × 10 10 years half-life), for which there is no quantitative limitation. Taking advantage of the wide experience of our group in chemical bath deposition (CBD) of PbS thin films 16 – 20 , we have recently reported on a new method for alloying chemical bath deposited (CBD) PbS thin films by forming a solid solution with 232 Th 21 , 22 . Although PbS differs from the commonly studied metal oxides, it holds several advantages as a model system; The narrow and direct band gap establishes a new class of physical properties for damage studies, such as monitoring formation and annihilation of discrete defect-correlated energy levels in the forbidden gap.…”