Study of CdTe epitaxial growth on (211)B GaAs by molecular-beam epitaxy

Abstract

Recently, misoriented (100)GaAs or (211)GaAs substrates have been found to be favored for HgCdTe and CdTe epitaxial growths, due to low occurrence of crystalline defects. It was previously reported that both tilted (211) and (133)CdTe were grown on (211)B GaAs, like on (100)GaAs, and that (133)CdTe seemed to have better crystallinity than tilted (211)CdTe. However, these results were obtained only at substrate temperature ∼300 °C, and the occurrence of both growth orientations has not been clear yet. In this article, substrate temperature dependence of CdTe growth on (211)B GaAs substrate is studied in detail, from the view points of crystallinity and surface morphology. It turns out that these orientations can be controlled by the initial substrate temperature, i.e., tilted (211)CdTe appears at substrate temperature below 290 °C, and above 290 °C (133)CdTe can be grown. Furthermore, double-crystal rocking curve-full width at half-maximum reaches 60 arcsec for (133)CdTe/(211)B GaAs. Finally, a model for the occurrence of both tilted (211) and (133) CdTe growths was qualitatively proposed.

Molecular-beam epitaxial growth of CdTe(112) on Si(112) substrates

“…For all vicinal Si͑112͒ surfaces investigated, the CdTe epilayer is observed to tilt away from the Si͓112͔ direction by 2°toward the ͓001͔ direction. This tilt is in the same direction but smaller than the 4°tilt previously observed 5 for growth of CdTe͑112͒ on GaAs/Si substrates and is consistent with the 3°Ϯ1°tilt previously reported 16 for CdTe͑112͒ epitaxy on GaAs͑112͒B. The data of Fig.…”

“…Moreover, this result compares favorably with the best previously published results of 90 arcsec for 8-m-thick CdTe͑112͒B on GaAs/Si 5 and 90-300 arcsec for 4-m-thick CdTe͑112͒B on GaAs͑112͒B. 16,17 Further x-ray diffraction characterization has been undertaken to determine the relative tilt between the CdTe͑112͒ epilayer and the Si͑112͒ substrate as a function of the Si misorientation from ͑112͒ toward ͓111͔. Figure 2 illustrates the 2°tilt away from ͓111͔ that is observed for the CdTe epilayer.…”

“…The Everson 15 etch has been found to give reproducible results when applied to the CdTe͑112͒/Si͑112͒ epitaxial structures of this study. Preliminary attempts to use other defect etches, such as the Inoue etch 18 employed by others 16 for CdTe͑112͒/GaAs͑112͒, gave erratic results characterized by large nonuniformity across a given sample. Well-defined, triangular etch pits were formed with 30 s exposure to the lactic/nitric/HF solution, which removed approximately 1 m of heteroepitaxial CdTe͑112͒.…”

Microstructure of Heteroepitaxial ZnTe Grown on GaAs(211)B by Molecular Beam Epitaxy

“…This was done under Te flux, to prevent the possible desorption of As and to produce a Te stabilized (211)B surface for epitaxial growth. 12,13 Finally, the substrate was cooled to the growth temperature of 275°C. Growth was initiated when the ZnTe flux was stable, as monitored by an ion gauge.…”

X-ray reciprocal space mapping of a (112) oriented HgTe/Hg0.1Cd0.9Te superlattice

“…[1][2][3][4][5][6][7] The reduction in symmetry induced by a change from the conventional ͓001͔ to higher index growth directions induces an anisotropic strain that lifts the cubic symmetry, removing degeneracy in the valence band and warping the constant energy surfaces. Recent studies have shown that the growth and physical properties of the heterostructures depend strongly on surface orientations.…”