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

Markunas

et al. 2008

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.

Section: Resultsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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

Benson

Markunas

et al. 2008

“…Additional details of this growth process are provided in the literature. 12 Because this CdTe buffer layer acts as the template upon which the infrared-sensing HgCdTe will be grown, it is critical that the density of TDs in this layer is minimized. Several novel approaches have been attempted to reduce this density in CdTe buffer layers, including epitaxial lateral overgrowth, wafer bonding and layer transfer, and CdTe epitaxy on patterned substrates.…”

Section: Introductionmentioning

confidence: 99%

Si Wafer Thinning Techniques Compatible With Epitaxy of CdTe Buffer Layers

Markunas

Smith

et al. 2011

Reduction of threading dislocation density is critical for improving the performance of HgCdTe detectors on lattice-mismatched alternative substrates such as Si. CdTe buffer layers grown by molecular beam epitaxy (MBE), with thicknesses on the order of 8 lm to 12 lm, have helped reduce dislocation densities in HgCdTe layers. In this study, the reduction of threading dislocation densities in CdTe buffer layers grown on locally thinned Si substrates was examined. A novel Si back-thinning technique was developed that maintained an epiready front surface and achieved Si thicknesses as low as 1.9 lm. Threading dislocation densities, acquired by defect decoration techniques, were reduced by as much as 60% for CdTe buffer layers grown on these thinned regions when compared with unthinned regions. However, this reduction is inconsistent with prior notions that threading dislocation propagation is dominated by image forces. Instead, the thickness gradient of thinned Si may play a larger role.

“…As-grown molecular beam epitaxy (MBE) (112)B CdTe/Si has a larger defect density and more disordered crystallinity than bulk (112)B CdZnTe substrates (see Table I and Refs. [1][2][3][4][5][6][7][8][9][10][11]. This results in MBE (112)B HgCdTe/CdTe/Si having a larger defect density and more disordered crystallinity than MBE (112)B HgCdTe/CdZnTe (Table I).…”

Section: Introductionmentioning

confidence: 99%

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

Benson

Smith

et al. 2009

Self Cite

Scanning electron microscopy (SEM), atomic force microscopy (AFM), and x-ray diffraction (XRD) measurements all indicate an approximate factor of ten increase in the Everson etch pit density (EPD) over standard Nomarski microscopy Everson EPD determination. A new (112)B CdTe/Si EPD etch has also been demonstrated which reduces the surface roughness of the etched epilayer and makes etch pit density determination less problematic.