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

Abstract

High crystalline quality epitaxial CdTe(112)B/ZnTe films were deposited by molecular-beam epitaxy directly onto vicinal Si(112) substrates, without use of GaAs interfacial layers. The films were characterized with x-ray diffraction, optical microscopy, and wet chemical defect etching. Single crystal, twin-free CdTe(112)B films exhibit structural quality exceeding that previously reported for CdTe(112)B heteroepitaxy on GaAs/Si(112) or GaAs(112)B substrates. X-ray rocking curve full width at half-maximum of 72 arcsec for CdTe(224) reflection and near-surface etch pit densities (EPD) of 2×106 cm−2 have been observed for 8-μm-thick CdTe films. EPD depth profiles indicate that the threading dislocation density decreases with increasing II–VI epilayer thickness up to approximately 5 μm thickness and saturates at 2×106 cm−2 for thickness exceeding 5 μm. The CdTe epilayer orientation was observed to tilt 2° away from the Si(112) substrate orientation toward the [001] direction.

The structure of the Si (211) surface

“…This orientation is of particular importance to CdTe and HgCdTe growth by MBE. [1][2][3][4][5][6] However, low-energy electron diffraction (LEED) investigations of stepped surfaces, such as (211), are a particularly difficult problem. The Si (211) surface has been investigated for over 20 years, but the conclusions 7-9 are inconsistent; specifically they do not agree with the results of recent scanning tunneling microscopy (STM) investigations [10][11][12][13][14][20][21][22] demonstrating the intractability of the problem.…”

Analysis of Dislocation Density in Pb(1−x)Sn x Se Grown on ZnTe/Si by MBE

“…Molecular-beam epitaxy (MBE) growth of II-VI materials such as ZnTe and CdTe on Si is well known. 6 We use a ZnTe/Si buffer for subsequent Pb (1Àx) Sn x Se growth by MBE. The ZnTe and Pb (1Àx) Sn x Se h220i spacing offer a compressive misfit of 0.45% at the growth temperature, 523 K. For Pb (1Àx) Sn x Se alloys, this misfit reduces with increasing SnSe and is >0.27% for Pb 0.91 Sn 0.09 Se.…”

Molecular beam epitaxy grown long wavelength infrared HgCdTe on Si detector performance

“…1 Silicon wafers offer many advantages due to their low cost, large available sizes, high mechanical strength, industrial maturity, and ability to thermally match the read-out integration chip. [1][2][3][4] Several materialsrelated challenges have, thus far, prevented the realization of this potential. First, the lattice-parameter mismatch between Si and HgCdTe is ϳ19% (a Si ϭ 5.43 Å, a CdTe ϭ 6.48 Å, a HgTe ϭ 6.453 Å).…”