Structural Analysis of CdTe Hetero-epitaxy on (211) Si

Abstract

X-ray diffraction full-width at half-maximum (XRD FWHM), reflection highenergy electron diffraction (RHEED), and atomic force microscopy (AFM) indicate a mosaic structure for molecular-beam epitaxy (MBE) (211)B CdTe/Si. AFM measurements indicate long, thin, small-angle-disoriented grains for CdTe/Si epilayers. These disoriented grains are $1 lm in the [111] direction and are $40 nm in the [011] direction. The RHEED pattern in the [111] direction depicts nearly ideal single-crystal periodicity. The RHEED pattern in the [011] direction is indicative of small-angle-disoriented crystalline grains. Scanning electron microscopy (SEM), AFM, and XRD measurements all indicate an approximate factor of 10 increase in the Everson etch pit density (EPD) over standard Nomarski microscopy Everson EPD determination.

Ex Situ Thermal Cycle Annealing of Molecular Beam Epitaxy Grown HgCdTe/Si Layers

“…This result is consistent with those of other studies that show a correlation between x-ray FWHM and defect density. 11 The variation of FWHM with the number of annealing cycles is shown in Fig. 6.…”

Topography and Dislocations in (112)B HgCdTe/CdTe/Si

“…The defect density of the CdTe/Si epilayer from laboratory A in Table III was also determined by x-ray diffraction (XRD) fullwidth at half-maximum (FWHM) measurements. 20 These measurements reported a defect density of $1 9 10 7 cm À2 . This again supports the proposition of improved EPD determination through the new etch and high-resolution etch pit imaging.…”

Plasma-Cleaned InSb (112)B for Large-Area Epitaxy of HgCdTe Sensors

“…The pattern indicates a crystalline surface, however, this is not the typical pattern expected for the stepped (112) surface. 34 This might be due to damage to the stepped surface or simply an alternative surface reconstruction.…”

“…7a, suggesting a more ordered crystallographic structure, thus providing the pristine InSb (112)B surface desired for appropriate MBE heteroepitaxy growth. 34 As mentioned previously, current technology development envisions that the next generation of infrared sensors will be based on large-format (megapixel) arrays of photovoltaic detectors with multispectral capabilities. Therefore, lateral and uniform oxide removal from the InSb surface must be accomplished for it to be used as a large-area lowcost alternative substrate, as these factors influence the final quality of the HgCdTe heterostructure.…”