Molecular beam epitaxial growth and characterization of Cd-based II–VI wide-bandgap compounds on Si substrates

Abstract

We have carried out a detailed study on the growth of Cd-based II-VI compounds on Si substrates using molecular beam epitaxy (MBE). CdTe, CdSe, CdSeTe, and CdZnSeTe layers were nucleated and grown on Si(211) substrates in order to study a broad range of semiconductor properties, such as crystal structure, fundamental bandgap, surface morphology, and defect and dislocation density as a function of the constituent elements. For structural characterization, we used transmission electron microscopy (TEM) and x-ray diffraction, which indicated that cubic Cd 1-x Se x Te material had been grown on Si substrates throughout the entire composition range. Likewise, photoreflectance (PR) and photoluminescence (PL) were used to measure the optical response in the near bandgap (E g ) region. Results indicated nonrandom ordering of CdSeTe/Si material. Studies on quaternary CdZnSeTe material indicated that Zn and Se concentrations directly impact surface morphology with extremely smooth surfaces obtained as Zn content is decreased.

Molecular Dynamics Simulations of CdTe / CdS Heteroepitaxy - Effect of Substrate Orientation

“…Cadmium telluride (CdTe) thin films are widely used in photovoltaic (Colegrove et al, 2012) (McCandless and Sites 2003) (Okamoto, Yamada, & Konagai 2001) and other optoelectronic applications (Liang et al, 2012) (Brill et al, 2005) (Heiss et al, 2006) due to its low production cost, a desired direct band gap of ~1.5 eV, and an excellent absorption coefficient of 6 × 10 4 m -1 at 600 nm. A variety of methods have been applied to synthesize CdTe films such as molecular beam epitaxy (MBE) (Kim et al, 2004) (Han, Kang, & Kim 1999), physical vapour deposition (PVD) (Moutinho et al, 2008), high vacuum evaporation (HVE) (Terheggen et al, 2003), and close space sublimation (CSS) (Paudel, Xiao, & Yan 2014) .…”

Se‐Se isoelectronic centers in high purity CdTe

“…1b) two main features: the first one consists of a red energy shift of the CdTe QWs near band-edge emission, whereas the second one reveals the appearance of sharp discrete lines at the low energy side: these lines are due to the recombination of excitons localized on Se impurities. The first feature, namely the reduction of the fundamental band gap, was reported in literature for II-VI and III-V alloys with a low concentration of substitutional atoms [4,5,8,9]. We would like to emphasize that this behavior is related to a band gap bowing due to clusters local order effect [3,4] or band anticrossing phenomenon [5].…”

Epitaxial growth of CdTe on Si through perovskite oxide buffers

“…9 The full-width at half-maximum (FWHM) of sample A1 is 115 arc seconds, which is comparable to (211) Cd(Zn,Se)Te grown on Si using standard buffer layer growth techniques. 10 Sample A2 has a wider FWHM because it was grown at higher temperature. 4 All FWHM data are included in Table I.…”